Nutrition and health

Objectives:
Diabetes prevention is a public health priority. Vitamin D supplementation may help prevent the development of diabetes in persons at increased risk. Therefore, this review article has been conducted.

Does vitamin D supplementation reduce risk of type 2 diabetes?

Study design:
This review article included 28 RCTs with 3,848 participants.

The sample size varied from 23 to 511.
The mean age of participants ranged from 26 years to 71 years.
The duration of follow-up across studies ranged from 2 months to 5 years, with a median follow-up of 22 weeks [interquartile range (IQR): 14 to 48 weeks], a duration long enough to detect changes in measured outcomes.

The average vitamin D supplementation dose of 88 µg/d (3500 IU/d).
All included trials measured the effect of vitamin D supplementation on serum 25(OH)D concentrations.

Results and conclusions:
The investigators found overall, serum 25(OH)D concentrations in the treated arms (vitamin D-supplemented groups) significantly improved by 45.1 nmol/L [95% CI = 41.3 to 48.9, p 0.001, I2 = 97.4%].

The investigators found compared with the control group, vitamin D supplementation significantly reduced HbA1c level by -0.48% [95% CI = -0.79 to -0.18, p = 0.002, I2 = 92.1%].
However, after adjusting the effect size for potential publication bias using the “trim and fill” method, 4 potentially missing studies were imputed in the funnel plot and the effect size increased from -0.48% [95% CI = -0.79 to -0.18] to -0.71% [95% CI = -1.02 to -0.39].

The investigators found compared with the control group, vitamin D supplementation significantly reduced fasting plasma glucose level by -0.46 mmol/L [95% CI = -0.74 to -0.19, p = 0.001, I2 = 92.4%].  
However, after adjusting the effect size for potential publication bias using the “trim and fill” method, 6 potentially missing studies were imputed in the funnel plot and the effect size increased -0.46 mmol/L [95% CI = -0.74 to ­0.19] to -0.72 mmol/L [95% CI =-1.02 to -0.42].

The investigators found compared with the control group, vitamin D supplementation significantly reduced HOMA-IR level by -0.39 [95% CI = -0.68 to -0.11, p = 0.007, I2 = 91.3%].
However, after adjusting the effect size for potential publication bias using the “trim and fill” method, 5 potentially missing studies were imputed in the funnel plot and the effect size increased from -0.39 [95% CI = -0.68 to -0.11] to -0.62 [95% CI = -0.92 to -0.32].

The investigators found in subgroup analysis both HbA1c and HOMA-IR showed a greater reduction over time among overweight/obese individuals compared with prediabetics [HbA1c = -0.98 ± 0.45 vs -0.29 ± 0.14, p = 0.1 and HOMA-IR = -0.62 ± 0.23 vs -0.07 ± 0.16, p = 0.05].

The investigators found in subgroup analysis vitamin D supplementation significantly decreased HbA1c [p = 0.05], fasting plasma glucose level [p = 0.05] and HOMA-IR [p = 0.1] to a greater extent when serum 25(OH)D concentration achieved was above 86 nmol/L.

The investigators found in subgroup analysis vitamin D supplementation for less than 6 months provided a larger effect size on HbA1c in comparison with long durations [-0.75 ± 0.33 vs -0.25 ± 0.11, p = 0.1].

The investigators found in subgroup analysis HbA1c showed greater improvement in populations with a mean age younger than 45 years in comparison with older populations [-1.15 ± 0.6 vs -0.30 ± 0.1, p = 0.05].

The investigators found in subgroup analysis greater reductions were found within HbA1c and fasting plasma glucose levels when baseline (at the beginning of the study) mean serum 25(OH)D concentration was ≥50 nmol/L, whereas the lowering effect was significantly less in the subgroup with baseline mean 25(OH)D 50 nmol/L [HbA1c = -0.79 ± 0.25 vs -0.14 ± 0.13, p = 0.04 and fasting plasma glucose level = -0.69 ± 0.21 vs -0.11 ± 0.10, p = 0.05].

The investigators concluded 88 µg/d vitamin D supplementation during 22 weeks improves glycemic measures and insulin sensitivity and may be useful as part of a preventive strategy for type 2 diabetes, particularly among overweight/obese individuals younger than 45 years.

Original title:
Vitamin D Supplementation, Glycemic Control, and Insulin Resistance in Prediabetics: A Meta-Analysis by Mirhosseini N, Vatanparast H, [...], Kimball SM.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016617/

Additional information of El Mondo:
Find more information/studies on diabetes and vitamin D right here.

HbA1c, FPG, HOMA-IR and plasma glucose after 2-hour oral glucose tolerance test (2HPG) are different parameters associated with (pre)diabetes.

 

Objectives:
High potato intake has been suggested as a risk factor for the development of type 2 diabetes. Therefore, this review article has been conducted.

Does potato intake increase risk of type 2 diabetes?

Study design:
This review article included 6 prospective cohort studies with a total of 4,545,230 person-year of follow-up and 17,758 diabetes cases.

Results and conclusions:
The investigators found for every increment of 1 serving/day of total potato consumption a significantly increased risk of 20% [HR = 1.20, 95% CI = 1.13 to 1.127, p 0.001, I2 = 27.1%, p for heterogeneity = 0.23] for type 2 diabetes both in men en women.

The investigators found for 2 servings/day of total potato consumption a significantly increased risk of 44% [HR = 1.44, 95% CI = 1.28 to 1.63] for type 2 diabetes both in men en women.

The investigators found for 3 servings/day of total potato consumption a significantly increased risk of 74% [HR = 1.74, 95% CI = 1.45 to 2.09] for type 2 diabetes both in men en women.

The investigators found significant evidence of a non-linear association between total potato consumption and risk of type 2 diabetes [X2 = 17.5, p for linearity 0.001].

The investigators concluded that long-term high consumption of potato (each serving a day increase) is strongly associated with increased risk of type 2 diabetes. These findings suggest that diet-health policy may be of importance in the prevention of diabetes.

Original title:
Potato consumption and risk of type 2 diabetes: A dose-response meta-analysis of cohort studies by Bidel Z, Teymoori F, […], Nazarzadeh M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30144898

Additional information of El Mondo:
Find more information/studies on diabetes right here.

According to the USDA Dietary Guidelines a serving of potato is 1 cup diced, mashed or baked or 1 medium boiled potato.

 

Objectives:
Several studies have been published about the effect of garlic on lipid profile and blood glucose in diabetic patients. Which, the results mostly contradict with each other. Therefore, this review article has been conducted.

Does garlic improve lipid profile and blood glucose in diabetic patients?

Study design:
This review article included 33 articles with a total of 1,273 individuals, with a mean of 39 samples per study.

Results and conclusions:
The investigators found the concentration of serum total cholesterol significantly decreased wih 16.87 mg/dL [95% CI = -21.01 to -12.73, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum LDL cholesterol (bad cholesterol) significantly decreased with 9.65 mg/dL [95% CI = -15.07 to -4.23, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum triglycerides significantly decreased with 12.44 mg/dL [95% CI = -18.19 to -6.69, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum HDL cholesterol (good cholesterol) significantly increased with 3.19 mg/dL [95% CI = 1.85 to 4.53, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum fasting blood sugar significantly decreased with 10.90 mg/dL [95% CI = -16.40 to -5.40, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum HbA1c significantly decreased with 0.60 mg/dL [95% CI = -0.98 to -0.22, p = 0.001] in the garlic group when compared with the placebo group.

The investigators concluded that garlic improves lipid profile as well as glucose parameters and can be therapeutically effective in patients suffering from cardiovascular diseases and diabetes.

Original title:
The effect of garlic on lipid profile and glucose parameters in diabetic patients: A systematic review and meta-analysis by Shabani E, Sayemiri K and Mohammadpour M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30049636

Additional information of El Mondo:
Find more information/studies on diabetes, cholesterol, meta-analyses/heterogeneity and garlic right here.

 

Objectives:
The purpose of this review article is to review previously published meta-analyses on the effectiveness of dietary fiber on type 2 diabetes.

Study design:
This umbrella review article included 16 meta-analyses.

Results and conclusions:
The investigators found in the meta-analyses when comparing highest versus lowest dietary fiber intake, a statistically significant reduced risk of 15 to 19% [RR = 0.81-0.85] for type 2 diabetes. However, statistically significant heterogeneity was observed in all of these meta-analyses.

The investigators found in the meta-analyses when comparing highest versus lowest dietary cereal fibers, a statistically significant reduced risk of 13 to 33% [RR = 0.67-0.87] for type 2 diabetes. However, statistically significant heterogeneity was observed in all of these meta-analyses.

The investigators found in the meta-analyses of supplementation studies using β-glucan or psyllium fibers on type 2 diabetic participants, statistically significant reductions were identified in both fasting blood glucose concentrations and glycosylated hemoglobin percentages.

The investigators concluded that those consuming the highest amounts of dietary fiber, especially cereal fiber, may benefit from a reduction in the incidence of developing type 2 diabetes. May benefit because statistically significant heterogeneity was observed in all of these meta-analyses.
There also appears to be a small reduction in fasting blood glucose concentration, as well as a small reduction in glycosylated hemoglobin percentage for individuals with type 2 diabetes who add β-glucan or psyllium to their daily dietary intake.

Original title:
Dietary Fiber Intake and Type 2 Diabetes Mellitus: An Umbrella Review of Meta-analyses by McRae MP.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29628808

Additional information of El Mondo:
Find more information/studies on diabetes, meta-analyses/heterogeneity and dietary fiber right here.

 

Objectives:
The association between dietary protein intake and type 2 diabetes risk has been inconsistent in the previous epidemiological studies. Therefore, this review article (meta-analysis) has been conducted.

Is there an association between dietary protein intake and type 2 diabetes risk?

Study design:
This review article included 10 prospective cohort studies with a total of 34,221 type 2 diabetes cases.
No publication bias was detected.

Results and conclusions:
The investigators found after adjustment of potential confounders, a 5% of energy (5 En%) increment from dietary total protein intake was related to a significantly 9% [95 CI = 1.04-1.13, I2 = 42.0%] higher risk of type 2 diabetes. The results were robust in sensitivity analysis.

The investigators found after adjustment of potential confounders, a 5% of energy (5 En%) increment from dietary animal protein intake was related to a significantly 12% [95 CI = 1.08-1.17, I2 = 14.0%] higher risk of type 2 diabetes. The results were robust in sensitivity analysis.

The investigators found after adjustment of potential confounders, a significant U-shaped curve was observed for plant protein intake with the most risk reduction at about 6% of energy from plant protein intake [p nonlinearity = 0.001]. The results were robust in sensitivity analysis.

The investigators concluded that the consumption of protein, particularly animal protein increases risk of type 2 diabetes.

Original title:
Dietary protein intake and risk of type 2 diabetes: a dose-response meta-analysis of prospective studies by Zhao LG, Zhang QL, [...], Xiang YB.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29858629

Additional information of El Mondo:
Find more information/studies on diabetes and protein right here.

 

Objectives:
The association between coffee consumption and the level of C-reactive protein (CRP) has been evaluated in several epidemiological studies with conflicting results. Therefore, this meta-analysis (systematic review) has been conducted.

Does coffee consumption reduce level of C-reactive protein in humans?

Study design:
This review article included a total of 9 cross-sectional studies.

Results and conclusions:
The investigators found according to the combined standard mean difference (SMD) between the highest and the lowest coffee intake category, coffee consumption was associated with a significantly lower level of serum CRP level [SMD = -0.34, 95% CI = -0.62 to -0.06, p = 0.016].

The investigators found subgroup analysis for CRP marker showed that coffee consumption was associated with a significantly lower level of serum high-sensitivity CRP (hsCRP) [SMD = -0.51, 95% CI = -0.88 to -0.14, p = 0.007], but not standard CRP [SMD = 0.02, 95% CI = -0.28 to 0.32, p = 0.913].

The investigators concluded that coffee consumption is associated with a lower level of serum CRP, particularly serum high-sensitivity CRP. However, more well-designed prospective cohort studies are needed to elaborate the concerned issues further.

Original title:
Is coffee consumption associated with a lower level of serum C-reactive protein? A meta-analysis of observational studies by Zhang Y and Zhang DZ.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29405789

Additional information of El Mondo:
Find more information/studies on coffee and chronic disease right here.

 

Objectives:
Epidemiological studies exploring the role of flavonoids intake in preventing type 2 diabetes mellitus (T2DM) showed inconsistent results. Therefore, this review article (meta-analysis) has been conducted.

Does flavonoids intake decrease risk of developing type 2 diabetes?

Study design:
This review article included 10 independent cohorts published between 2002 and 2017 with a total of 312,015 participants, of which 19,953 type 2 diabetes cases were identified during the follow-up periods from 4 to 28 years.
All participants were free of type 2 diabetes at baseline (at the beginning of the study), with age ranging from 28 to 75 years.
Dietary flavonoids intake was evaluated using food-frequency questionnaire and type 2 diabetes was frequently ascertained through medical records.
In the original studies, the median intake level of total flavonoids was 8.9 to 501.8 mg/day for the lowest categories and 33.2 to 1452.3 mg/day for the highest categories.
The most commonly adjusted variables included age, sex, total energy intake, body mass index, smoking, alcohol consumption and physical activity.
All included studies had a NOS score of ≥7, with an average score of 7.9, indicating the presence of high methodological quality.

There was no indication of publication bias from visual inspection of the funnel plot, which was further confirmed by Egger test [p = 0.253].

Results and conclusions:
The investigators found when compared with the lowest intake, the highest intake of total flavonoids was associated with a significantly 9% decreased risk of type 2 diabetes [RR = 0.91, 95% CI = 0.86-0.96, I2  =  21%, p =  0.257].
In stratified analyses, the pooled RR for total flavonoids intake was not modified by sample size, sex, follow-up duration and study location.
Leave-one-out sensitivity analysis showed that no individual study had a significant influence on the final result.

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of anthocyanidins significantly decreased risk of type 2 diabetes with 11% [RR = 0.89, 95% CI = 0.82-0.95].

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of flavan-3-ols significantly decreased risk of type 2 diabetes with 14% [RR = 0.86, 95% CI = 0.78-0.95].

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of flavonols significantly decreased risk of type 2 diabetes with 14% [RR = 0.86, 95% CI = 0.80-0.94].

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of isoflavones significantly decreased risk of type 2 diabetes with 9% [RR = 0.91, 95% CI = 0.84-0.98].

The investigators found in 9 cohort studies a curvilinear relationship between total flavonoids intake and type 2 diabetes risk [p for nonlinearity = 0.042] with a significant risk reduction at an intake of ≥550 mg/day.

The investigators found when assuming a linear association, the risk of type 2 diabetes was reduced by 5% [RR = 0.95, 95% CI = 0.93-0.97] for each 300-mg/day increment in total flavonoids intake.

The investigators concluded that intakes of total flavonoids, particularly ≥550 mg/day, anthocyanidins, flavan-3-ols, flavonols and isoflavones are associated with significantly decreased risks of type 2 diabetes in the highest versus lowest analyses. Additionally, the dose-response analysis suggest a curvilinear relationship of total flavonoids intake with type 2 diabetes risk; when assuming a linear manner, the risk of type 2 diabetes is reduced by 5% for an increment of 300 mg/day in total flavonoids intake.

Original title:
Flavonoids intake and risk of type 2 diabetes mellitus: A meta-analysis of prospective cohort studies by Xu H, Luo J, [...], Wen Q.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959406/

Additional information of El Mondo:
Find more information/studies on diabetes and flavonoids right here.

Objectives:
There is an increasing trend in the consumption of poor-quality diets worldwide, contributing to the increase of non-communicable diseases. Diet directly influences physiological composition and subsequently physical health. Studies have shown that dietary macronutrient and energy content can influence the proportion of intramuscular fat (IMF), which mediates various metabolic and endocrine dysfunction. Therefore, this review article has been conducted.

Do different types of dietary macronutrient intake increase the proportion of intramuscular fat?

Study design:
This review article included 13 trials (RCTs, quasi-RCTs, controlled trials, randomized controlled crossover trials or controlled crossover trials).

High-fat diets were diets with a proportion of fat between 38 and 85 En%. Participants in high-fat diets were all young to middle aged adults with ages varying between 18 and 50 years.

Participants in starvation diets (a decrease of 25% calorie from weight maintenance energy requirements) and hypocaloric diets (890 calories per day, until 15% weight reduction) followed the diet for 8 days with a 3-week washout period in between.

Cohen’s criteria were used to determine the effect size of SMDs, where a SMD between 0.2 and 0.5 is small, a SMD between 0.5 and 0.8 is moderate and a SMD above 0.8 is large. SMDs below 0.2 were considered unsubstantial.

Results and conclusions:
The investigators found in 6 studies with in a total of 134 participants receiving a high-fat intervention and 135 people receiving a control intervention, that high-fat diets (38 and 85 En% fat) significantly increased the proportion of intramuscular fat [SMD = 1.24, 95% CI = 0.43-2.05, p  = 0.003, I2 = 87%].  
Sensitivity analysis (excluding studies with a quality value 20, smallest sample size 8 and those that do not specify participant characteristics) showed a significantly SMD of 1.26 [95% CI = 0.23-2.28, p = 0.02]. 

The investigators found diets with an increased proportion of carbohydrates decreased the proportion of intramuscular fat.
However, increasing caloric intake with carbohydrates compared to a standardized diet (55 En% carbohydrates, 30 En% fat and 15 En% protein) increased the proportion of intramuscular fat.

The investigators found starvation diets (a decrease of 25% calorie from weight maintenance energy requirements) increased intramuscular fat stores and hypocaloric diets (890 calories per day, until 15% weight reduction) did not result in any intramuscular fat proportion changes.

The investigators concluded that high-fat diets (38 y 85 En%), excessive caloric intake in the form of carbohydrates and short-term starvation diets are associated with increases in the proportion of intramuscular fat. However, further studies are needed to assess the effects of macronutrient combinations on intramuscular fat and the influence of diet-induced intramuscular fat alterations on health outcomes. In addition, intramuscular fat poses a possibly effective clinical marker of health.

Original title:
The Effects of Diet on the Proportion of Intramuscular Fat in Human Muscle: A Systematic Review and Meta-analysis by Ahmed S, Singh D, [...], Kumbhare D.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826234/

Additional information of El Mondo:
Find more information/studies on fat and carbohydrates consumption and diabetes right here.

Higher intramuscular fat levels are positively associated with insulin resistance and an increased risk of developing type 2 diabetes.

Objectives:
Observationally, homocysteine is associated with higher risk of diabetes. Folate, which reduces homocysteine, is promising for the prevention and treatment of diabetes. Previous meta-analysis (review) of 3 trials suggested folate might lower hemoglobin A1c (HbA1c). Therefore, this review article (meta-analysis) has been conducted.

Have folic acid supplementation positive effects on insulin resistance and glycemic control, like HbA1c level and fasting glucose level?

Study design:
This review article included 18 RCTs with in total of 21,081 people with/without diabetes.

Results and conclusions:
The investigators found that folic acid (folate) supplementation significantly reduced fasting glucose level with 0.15 mmol/L [95% CI = -0.29 to -0.01]. Significant means that there is an association with a 95% confidence.

The investigators found that folic acid (folate) supplementation significantly reduced homeostatic model assessment-insulin resistance (HOMA-IR) with 0.83 [95% CI = -1.31 to -0.34].

The investigators found that folic acid (folate) supplementation significantly reduced fasting insulin level with 1.94 μIU/mL [95% CI = -3.28 to -0.61].

The investigators found that folic acid (folate) supplementation had no clear effect on diabetes or HbA1c level.

The investigators concluded that folic acid (folate) supplementation reduces both fasting glucose level, fasting insulin level and homeostatic model assessment-insulin resistance (HOMA-IR) but it has no effect on diabetes or HbA1c level.

Original title:
The effects of folate supplementation on glucose metabolism and risk of type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials by Zhao JV, Schooling CM and Zhao JX.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29501221

Additional information of El Mondo:
Find more information/studies on diabetes and folic acid right here.

Patients with diabetes often have both an increased fasting glucose level, HOMA-IR value and fasting insulin level.

Objectives:
The increasing prevalence of diabetes in the United Kingdom and worldwide calls for new approaches to its management and diets with low glycaemic index have been proposed as a useful means for managing glucose response. However, there are conflicting reports and differences in the results of studies in terms of their effectiveness. Furthermore, the impact of low-glycaemic index diets (low GI-diets) and their long-term use in patients with type 2 diabetes remains unclear. Therefore, this review article (meta-analysis) has been conducted.

Do patients with type 2 diabetes mellitus benefit from low-GI diets?

Study design:
This review article included 6 RCTs.

Results and conclusions:
The investigators found in 2 RCTs that low-glycaemic index (low-GI) diet resulted in a significant improvement in glycated haemoglobin (HbA1c) [0.05]:
low-GI diet Δ = -0.5% [95% CI = -0.61% to -0.39%] vs. high-cereal fibre diet Δ = -0.18% [95% CI = -0.29% to -0.07%] and;
low-GI legume diet Δ = -0.5% [95% = -0.6% to -0.4%] vs. high-wheat fibre diet Δ = -0.3% [95% Cl = -0.4 to -0.2%].

The investigators found in 4 RCTs significant improvements in fasting blood glucose in low-GI diets compared to higher-GI diets or control:
low-GI diet = [150.8 ± 8.7] vs. higher-GI diet = [157.8 ± 10.4 mg/dL, mean ± SD, p = 0.43];
low-GI diet = [127.7] vs. high-cereal fibre diet = [136.8 mg/dL, p = 0.02];
low-GI diet = [6.5 (5.6-8.4)] vs. standard diabetic diet = [6.7 (6.1-7.5 mmol/L), median and interquartile range p > 0.05] and;
low-GI diet = [7.3 ± 0.3] vs. conventional carbohydrate exchange diet = [7.7 ± 0.4 mmol/L, mean ± SEM (Standard Error of Mean), p 0.05].

The investigators concluded that the low-GI diet is more effective in controlling glycated haemoglobin (HbA1c) and fasting blood glucose compared with a higher-GI diet or control in patients with type 2 diabetes. It will useful to evaluate the long-term effectiveness of low-glycaemic index diet in patients with type 2 diabetes.

Original title:
The Effect of Dietary Glycaemic Index on Glycaemia in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Ojo O, Ojo OO, [...], Wang XH.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872791/

Additional information of El Mondo:
Find more information/studies on diabetes and GI-diets right here.

A low-GI diet is a diet with a lot of products/meals with a low GI.
Products/meals with a low GI are products/meals with a GI-number of 55 or less.
In daily life, products/meals with a low GI contain at least 1.5 grams fiber per 100 kcal. These products and meals contain at least 1.5 grams fiber per 100 kcal.
 

Objectives:
Type 2 diabetes mellitus (T2DM) is one of the most important public health issues. Vitamin K supplementation might have favorable effect on risk factors of T2DM. Therefore, this review article (meta-analysis) has been conducted.

Have vitamin K supplementation favorable effects on risk factors of type 2 diabetes mellitus?

Study design:
This review article included 5 RCTs with in total of 533 participants.

There was no evidence of publication bias.

Results and conclusions:
The investigators found overall, meta-analysis did not show any beneficial effect of vitamin K supplementation on both:
-fasting blood sugar levels [-0.91 mg/dL, 95% CI = -2.57 to 0.76, p = 0.28];
-fasting insulin levels [-0.35 μIU/mL, 95% CI = -1.70 to 1.00, p = 0.61];
-HOMA-IR [-0.06, 95% CI = -0.32 to -0.19, p = 0.63] and
-2-h oral glucose tolerance test [-4.00 mg/dL, 95% CI = -20.00 to 11.99, p = 0.62].

The investigators found sensitivity analysis showed that overall estimates were not affected by elimination of any study.

The investigators concluded that vitamin K supplementation has no significant effect on glycemic control in healthy subjects. However, further studies should be performed on diabetic and pre-diabetic patients to determine the effect of vitamin K supplementation on impaired glycemic control.

Original title:
Effect of Vitamin K Supplementation on Glycemic Control: A Systematic Review and Meta-Analysis of Clinical Trials by Shahdadian F, Mohammadi H and Rouhani M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29523009

Additional information of El Mondo:
Find more information/studies on diabetes and vitamin K right here.
 

Objectives:
The actual effects of L-carnitine administration on leptin serum level is inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Does L-carnitine supplementation reduce leptin serum level?

Study design:
This review article included 7 RCTs with 325 cases (group with L-carnitine administration) and 330 controls (group without L-carnitine administration).

Subgroup analysis to find the sources of heterogeneity showed that L-carnitine dosage [ 2 g: I2 = 00.0%, p = 0.408] and study population [diabetes: I2 = 46.7%, p = 0.153 and non-diabetes: I2 = 15.1%, p = 0.317] were the potential sources of heterogeneity.

Results and conclusions:
The investigators found that L-carnitine supplementation had no significant effect on serum leptin concentrations [WMD = -0.565 ng/mL, 95% CI = -2.417 to 1.287, p = 0.550, I2 = 84.3%, p  0.0001].

The investigators found in subgroup analysis that  ≥ 2 mg L-carnitine supplementation significantly reduced serum leptin concentrations [WMD = -2.742 ng/mL, 95% CI = -3.039 to -2.444, p  0.001].

The investigators found in subgroup analysis that L-carnitine supplementation significantly reduced serum leptin concentrations in diabetic patients [WMD = -2.946 ng/mL, 95% CI = -3.254 to -2.638, p  0.001].

The investigators found in subgroup analysis that L-carnitine supplementation during 12 weeks significantly reduced serum leptin concentrations [WMD = -2.772 ng/mL, 95% CI = -3.073 to -2.471, p  0.001].

The investigators concluded that at least 3 mg L-carnitine per day in the course of 12 weeks reduce serum leptin concentrations, especially in diabetic patients.

Original title:
The effect of L-carnitine supplementation on serum leptin concentrations: a systematic review and meta-analysis of randomized controlled trials by Nazary-Vannani A, Ghaedi E, […], Varkaneh HK.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29453657

Additional information of El Mondo:
Find more information/studies on diabetes and L-carnitine and diabetes right here.

L-carnitine is a non-essential amino acid, which is also found in foods.

Objectives:
Fish oil supplementation has been shown to be associated with a lower risk of metabolic syndrome and benefit a wide range of chronic diseases, such as cardiovascular disease, type 2 diabetes and several types of cancers. However, the evidence of fish oil supplementation on glucose metabolism and insulin sensitivity is still controversial. Therefore, this review article (meta-analysis) has been conducted.

Does fish oil supplementation improve insulin sensitivity in humans?

Study design:
This review article included a total of 17 RCTs with 672 participants. One of the 17 studies was crossover design and others were parallel design.
The doses of active ingredients of fish oil (n-3 fatty acids) ranged from 1 g/d to 4 g/d. Duration of the interventions was ranged from 4 weeks to 24 weeks.
There was no suggestion of small study effect based on visual inspection of the funnel plot. Results of the Egger’s (p = 0.78) and Begg’s (p = 0.43) tests showed that there was no potential publication bias.

Results and conclusions:
The investigators found pooled analysis showed that fish oil supplementation had no effects on insulin sensitivity overall [SMD = 0.17, 95% CI = -0.15 to 0.48, p = 0.292, I2 = 58.1%, p = 0.001].

The investigators found subgroup analysis showed that fish oil supplementation significantly improved insulin sensitivity among people who were experiencing at least one symptom of metabolic disorders [SMD = 0.53, 95% CI = 0.17 to 0.88, p 0.001].

The investigators found subgroup analysis showed a positive effect of fish oil on insulin sensitivity among the short-term intervention group (12 weeks) rather than the long-term intervention group [SMD = 0.31, 95% CI = 0.01-0.61, p = 0.04].

The investigators found subgroup analysis showed that fish oil had no effects on insulin sensitivity among the healthy people or people with T2DM.

The investigators found there were no significant differences between subgroups of methods of insulin sensitivity and doses of omega-3 polyunsaturated fatty acids (n-3 PUFA) of fish oil supplementation.

The investigators found in sensitivity analysis that summary results did not differ significantly when omitting studies one at a time.

The investigators concluded that fish oil supplementation during 12 weeks improves insulin sensitivity among people who were experiencing at least one symptom of metabolic disorders.

Original title:
Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis by Gao H, Geng T, [...], Zhao Q.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5496233/

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Objectives:
The potential glucose-lowering effects of pomegranate have been reported in animal and observational studies, but intervention studies in humans have generated mixed results. Therefore, this review article (meta-analysis) has been conducted.

What are the effects of pomegranate supplementation on measures of glucose control, insulin levels and insulin sensitivity in humans?

Study design:
This review article included 16 RCTs with 538 subjects. 14 trials adopted parallel study designs and the 2 remaining trials used crossover designs.
The total number of subjects included in each study ranged from 14 to 74 subjects.
The mean age of participants in each trial ranged from 30 to 70 years, with differing age ranges in most studies.
11 studies used pomegranate juice as a supplement (the dosage ranged from 120 to 500 ml/day).
2 studies used pomegranate seed oil as treatments (the dosage ranged from 400 to 2000 mg/day).
3 studies utilized pomegranate extract as the intervention (the dosage ranged from 710 to 1420 mg/day).  
The duration of the pomegranate intervention varied from 1 to 12 weeks (median: 5.5 weeks).

Overall, significant heterogeneity was detected for FBI and HOMA-IR, but subgroup analysis could not identify factors significantly influencing these parameters.
No significant publication bias was found.

Results and conclusions:
The investigators found that pomegranate did not significantly affect the measures of:
-FBG (fasting blood glucose) [WMD = -0.6 mg/dL, 95% CI = -2.79 to 1.58, p = 0.59, I2 = 0%];
-FBI (fasting blood insulin) [WMD = 0.29 μIU/mL, 95% CI = -1.16 to 1.75, p = 0.70, I2 = 60.4%];
-HOMA-IR (homeostatic model assessment of insulin resistance) [WMD = -0.04, 95% CI = -0.53 to 0.46, p = 0.88, I2 = 59.8%] or;
-HbA1c (glycated haemoglobin) [WMD = -0.11%, 95% CI = -0.39 to 0.18, p = 0.46, I2 = 0%].
These results were robust in sensitivity analysis.

The investigators found meta-regression analysis showed that the factor (dose of pomegranate juice supplementation) was not associated with the treatment effects on FBG level [coefficient = -0.006, 95% CI = -0.023 to 0.011, p = 0.46].

The investigators found no significant difference in the FBG-lowering effect between trials that were conducted in subjects with cardiovascular disease risk [WMD = 0.30 mg/dL, 95% CI = -2.36 to 2.97, p = 0.82] and those that were conducted in healthy individuals [WMD = -2.53 mg/dL, 95% CI = -6.36 to 1.30, p = 0.19].

The investigators found no statistically significant differences in the pooled effects of pomegranate on FBG in the subgroups stratified by study designs, intervention durations, types of intervention, baseline BMI and baseline FBG levels (FBG levels at the beginning of the studie).

The investigators concluded pomegranate supplements have no favourable effect on improvements in glucose and insulin metabolism. The current evidence suggests that daily pomegranate supplementation is not recommended as a potential therapeutic strategy in glycemic management. Further large-scale RCTs with longer duration are required to confirm these results.

Original title:
Lack of efficacy of pomegranate supplementation for glucose management, insulin levels and sensitivity: evidence from a systematic review and meta-analysis by Huang H, Liao D, […], Zhu Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5629805/

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Objectives:
Do patients with type 2 diabetes benefit from a low carbohydrate diet?

Study design:
This review article included a total of 9 RCTs with 734 patients with type 2 diabetes.

Results and conclusions:
The investigators found that low carbohydrate diet significantly reduced HbA1c level [WMD = -0.44, 95% CI = -0.61 to -0.26, p= 0.00] of patients with type 2 diabetes.

The investigators found that low carbohydrate diet significantly reduced triglycerides concentration [WMD = -0.33, 95% CI = -0.45 to -0.21, p = 0.00] of patients with type 2 diabetes.

The investigators found that low carbohydrate diet significantly increased HDL cholesterol concentration (WMD = 0.07, 95% CI = 0.03 to 0.11, p = 0.00] of patients with type 2 diabetes.

The investigators found that low carbohydrate diet was not associated with decreased level of total cholesterol and LDL cholesterol.

The investigators found subgroup analyses showed that short term intervention of low carbohydrate diet was effective for weight loss [WMD = -1.18, 95% CI = -2.32 to -0.04, p = 0.04] in patients with type 2 diabetes.

The investigators concluded there is a beneficial effect of low carbohydrate diet intervention on glucose control in patients with type 2 diabetes. The low carbohydrate diet intervention also has a positive effect on triglycerides and HDL cholesterol concentrations, but without significant effect on long term weight loss.

Original title:
Efficacy of low carbohydrate diet for type 2 diabetes mellitus management: A systematic review and meta-analysis of randomized controlled trials by Meng Y, Bai H, […], Chen L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28750216

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A low carbohydrate diet is a diet that is largely made up of meals/products with 20-40 En% carbohydrate. Practically, this means that all meals/products that you eat on a daily basis should on average contain 20-40 En% carbohydrate.
20-40 En% carbohydrate means that the total amounts of carbohydrate make up for a 20-40% of the total kcal of the diet. Check here which products contain 20-40 En% carbohydrate.

Objectives:
Polyunsaturated fats (PUFAs) have been shown to reduce type 2 diabetes (T2DM) risk and improve insulin responsiveness in T2DM subjects, but whether the plant sources of omega-3 PUFA (alpha-linolenic acid [ALA]) have an effect on glycemic control requires further investigation. Therefore, this review article (meta-analysis) has been conducted.

Does alpha-linolenic acid dietary intake reduce diabetes risk?

Study design:
This review article included a total of 8 RCTs involving 212 participants with type 2 diabetes.
5 trials (62.5%) were parallel designs and 3 (37.5%) were crossover designs.
Participants were generally middle-aged (median age  =  54 years, range  =  47-64 years) and overweight or obese (median BMI  =  30.7, range  =  28.0-33.2).
Overall, participants had controlled diabetes (median HbA1c = 6.8%, median FBG = 7.95 mmol/L) and the majority of studies indicated the use of hypoglycemic drugs or other medications, although all studies excluded the use of insulin therapy.
The dose of ALA ranged from 1.5 to 7.4 g/day with a median assigned dose of 4.4, 5.4 and 5.4 g/day of ALA for trials that reported HbA1c, FBG and FBI, respectively.
The median duration of the treatment was 3 months, ranging from 2 to 12 months.
7 studies (87.5%) were considered high quality (MQS ≥8).

Results and conclusions:
The investigators found compared to a control diet, a median dose of 4.4 g/day of alpha-linolenic acid intake for a median duration of 3 months did not affect HbA1c (%) of patients with type 2 diabetes [MD =  -0.01, 95% = -0.32 to 0.31, p  =  0.96].

The investigators found compared to a control diet, a median alpha-linolenic acid dose of 5.4 g/day did not lower fasting blood glucose (FBG) of patients with type 2 diabetes [MD  = 0 .07, 95% CI = -0.61 to 0.76, p  = 0 .84] or fasting blood insulin (FBI) of patients with type 2 diabetes [MD  =  7.03, 95% CI = -5.84 to 19.89, p  = 0 .28].

The investigators found summary effect estimates were generally compromised by considerable and unexplained heterogeneity [I2 ≥ 75%].

The investigators found in the subgroup analysis of continuous predictors, a reduction in HbA1c (%) and FBG (mmol/L) was significantly associated with an increased intake of ALA.

The investigators found further adjustment for publication bias using Duval and Tweedie's trim-and-fill analysis provided an adjusted, significant MD of 0.25 [95% CI = -0.38 to -0.12, 0.001) for HbA1c (%).

The investigators concluded alpha-linolenic acid-enriched diet with a median alpha-linolenic acid dose of 4.4 g/day during 3 months has no effects on HbA1c, FBG or FBI in patients with type 2 diabetes. The scarce number of existing RCTs and the presence of heterogeneity in the meta-analysis limit the ability to make firm conclusions about alpha-linolenic acid in type 2 diabetes management. The potential for alpha-linolenic acid to have dose-dependent effects warrants further research in this area.

Original title:
The effect of alpha-linolenic acid on glycemic control in individuals with type 2 diabetes: A systematic review and meta-analysis of randomized controlled clinical trials by Jovanovski E1, Li D, […], Vuksan V.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5457843/

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4.4 g/day alpha-linolenic acid can be achieved by taking 1 to 2 tablespoons of flax or salba-chia seeds or about 12 whole walnuts per day.

 

Objectives:
It has been unclear whether supplemental probiotics therapy improves clinical outcomes in type 2 diabetic patients. Therefore, this meta-analysis (systematic review) has been conducted.

Do probiotics supplements improve clinical outcomes in type 2 diabetic patients?

Study design:
This review article included 12 RCTs involving 684 type 2 diabetic patients.

Results and conclusions:
The investigators found a significant decreased glucose level in the probiotics group [pooled standardized mean difference = -0.18 mg/dL, 95% CI = -0.35 to -0.01, p = 0.04, I2 = 64%, p = 0.004] compared to the control group.

The investigators found a significant reduction in HbA1c in the probiotics group [pooled standardized mean difference = -0.38%, 95% CI = -0.62 to -0.14, p = 0.002, I2 = 0%, p = 0.72] compared to the control group.

The investigators found a significant reduction in fasting insulin level in the probiotics group [pooled standardized mean difference = -0.38, 95% CI = -0.59 to -0.18, p = 0.003, I2 = 0%, p = 0.81] compared to the control group.

The investigators found a significant reduced HOMA-IR level in the probiotics group [pooled standardized mean difference = -0.99, 95% CI = -1.52 to -0.4, p = 0.0002, I2 = 86%, p 0.00001] compared to the control group.

The investigators found a significant reduced CRP level in the probiotics group [pooled standardized mean difference = -1.34 mg/L, 95% CI = -1.76 to -0.92, p 0.00001, I2 = 90%, p 0.00001] compared to the control group.

The investigators found a non-significant reduction in both triglyceride levels [SMD = -0.23, 95% CI = -0.48 to 0.02, p = 0.07, I2 = 52%, p = 0.03] and cholesterol levels [total cholesterol: SMD = -0.18, 95% CI = -0.42 to 0.06, p = 0.14, I2 = 47%, p = 0.05 and LDL-cholesterol: SMD = -0.03, 95% CI = -0.20 to 0.14, p = 0.73, I2 = 3%, p = 0.41] in the probiotics group compared to the control group.

The investigators concluded that probiotics supplementation is associated with significant improvement in HbA1c and fasting insulin in type 2 diabetes patients. These results may provide evidence for encouraging use of probiotics in patients with type 2 diabetes mellitus. However, more randomized placebo-controlled trials with larger sample sizes are warranted to confirm these findings.

Original title:
Effect of Probiotics on Glucose and Lipid Metabolism in Type 2 Diabetes Mellitus: A Meta-Analysis of 12 Randomized Controlled Trials by Yao K, Zeng L, [...], Zou X.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491138/

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Objectives:
What is the relationship between intake of 12 major food groups and risk of type 2 diabetes (T2D)?

Study design:
This review article included prospective cohort studies.
The 12 major food groups are whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy, fish, red meat, processed meat and sugar-sweetened beverages (SSB).

The meta-evidence was graded "low" for legumes and nuts; "moderate" for refined grains, vegetables, fruit, eggs, dairy and fish; and "high" for processed meat, red meat, whole grains and sugar-sweetened beverages.

Results and conclusions:
The investigators found 6 out of the 12 food-groups showed a significant relation with risk of type 2 diabetes; 3 of them a decrease of risk with increasing consumption (whole grains, fruits and dairy) and 3 an increase of risk with increasing consumption (red meat, processed meat and sugar-sweetened beverages) in the linear dose-response meta-analysis.

The investigators found evidence of a non-linear relationship between fruits, vegetables, processed meat, whole grains and sugar-sweetened beverages and type 2 diabetes risk.

The investigators found optimal consumption of risk-decreasing foods resulted in a 42% reduction and consumption of risk-increasing foods was associated with a threefold type 2 diabetes risk, compared to non-consumption.

The meta-evidence was graded "low" for legumes and nuts; "moderate" for refined grains, vegetables, fruit, eggs, dairy and fish; and "high" for processed meat, red meat, whole grains, and sugar-sweetened beverages. Among the investigated food groups, selecting specific optimal intakes can lead to a considerable change in risk of type 2 diabetes.

The investigators concluded that a higher consumption of whole grains, fruits and dairy products reduces type 2 diabetes risk, while a higher consumption of red meat, processed meat and sugar-sweetened beverages increases type 2 diabetes risk.

Original title:
Food groups and risk of type 2 diabetes mellitus: a systematic review and meta-analysis of prospective studies by Schwingshackl L, Hoffmann G, […], Boeing H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28397016

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Objectives:
Olive oil (OO) as food is composed mainly of fatty acids and bioactive compounds depending from the extraction method. Both had been discussed as health promoting with still open questions. Therefore, this meta-analysis (systematic review) has been conducted.

Does olive oil intake reduce risk of type 2 diabetes?

Study design:
This review article included 4 cohort studies including 15,784 type 2 diabetes cases and 29 intervention trials.

Results and conclusions:
The investigators found the highest olive oil intake category showed a 16% reduced risk of type 2 diabetes [RR = 0.84, 95% CI = 0.77, 0.92) compared with the lowest. The reduced risk was significant.

The investigators found evidence for a nonlinear relationship between olive oil intake and the reduced risk of type 2 diabetes.

The investigators found in patients with type 2 diabetes that olive oil supplementation resulted in a significantly more pronounced reduction in HbA1c [MD = -0.27%, 95% CI = -0.37 to -0.17] and fasting plasma glucose [MD = -0.44 mmol/L, 95% CI = -0.66 to -0.22] as compared with the control groups.

The investigators concluded that the intake of olive oil is beneficial for the prevention and management of type 2 diabetes. This conclusion regards olive oil as food and might not been valid for single components comprising this food.

Original title:
Olive oil in the prevention and management of type 2 diabetes mellitus: a systematic review and meta-analysis of cohort studies and intervention trials by Schwingshackl L, Lampousi AM, […], Boeing H1.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28394365

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Objectives:
Nutrition therapy is an integral part of self-management education in patients with type 2 diabetes. Carbohydrates with a low glycemic index are recommended, but the ideal amount of carbohydrate in the diet is unclear. Therefore, this meta-analysis (systematic review) has been conducted.

Has carbohydrate restriction (below 45 En% carbohydrate) beneficial effects on glycemic control in type 2 diabetes?

Study design:
This review article included 10 RCTs. In total, 1,376 subjects with type 2 diabetes were included in this analysis. Forty-nine percent were male and the average age was 58 years. The majority were obese; mean BMI ranged from 26 kg/m² in an Asian population to 37 kg/m² in an American population.

The duration of the intervention varied from 3 to 24 months.

The average predefined targets for the assigned carbohydrate restriction were 25 En% (range 14-40 En%). The average reported intake was 30 En% (range 14-45 En%) after 3 or 6 months of intervention and 38 En% (range 27-45 En%) at 1 year (5 trials).

Results and conclusions:
The investigators found following a carbohydrate diet of 30 En% (range 14-45 En%) during 3 to 6 months significantly reduced HbA1c level of patients with type 2 diabetes with 0.34% [95% CI = 0.06 to 0.63] compared with a diet of 45-60 En% carbohydrate (high-carbohydrate diet).
Owing to heterogeneity, however, the quality of the evidence for this is only moderate. However, at 1 year or later, HbA1c level (seven trials included) was similar in the two groups.

The investigators found the greater the carbohydrate restriction, the greater the glucose-lowering effect [R = -0.85, p 0.01].

The investigators found the effect of the 2 types of diet on BMI/body weight, LDL cholesterol, QoL and attrition rate was similar throughout interventions.

The investigators concluded that carbohydrate restriction (below 45 En% carbohydrate) has a greater effect on glycemic control in type 2 diabetes than an high-carbohydrate diet in the short term. The magnitude of the effect was correlated to the carbohydrate intake, the greater the restriction, the greater glucose lowering, a relationship that has not been demonstrated earlier. However, in the long term, the glucose-lowering effect of high-carbohydrate diet (HCD) and low-carbohydrate diets (LCD) was similar.

Original title:
Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes by Snorgaard O, Poulsen GM, [...], Astrup A.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337734/

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Objectives:
Randomised controlled trials (RCTs) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation. Therefore, this meta-analysis (systematic review) has been conducted.

Has vitamin C supplementation a favorable effect on circulating biomarkers of glycaemic and insulin regulation?

Study design:
This review article included 22 RCTs with 937 participants.

Results and conclusions:
The investigators found overall, vitamin C supplementation did not modify glucose, HbA1c and insulin concentrations.

The investigators found, however, subgroup analyses showed that vitamin C supplementation significantly reduced glucose concentrations with 0.44 mmol/L [95% CI = -0.81 to -0.07, p =0.01] in patients with type 2 diabetes and in interventions with a duration greater than 30 days [-0.53%, 95% CI = -0.79 to -0.10, p = 0.02].

The investigators found vitamin C administration had greater effects on fasting [-13.63 pmol/L, 95% CI = -22.73 to -4.54, p 0.01] compared to postprandial insulin concentration. However, meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration.

The investigators found the effect size of vitamin C supplementation was associated with baseline BMI and plasma glucose levels and with the duration of the intervention.

The investigators concluded vitamin C supplementation has greater reduction in glucose concentrations in patients with type 2 diabetes, older individuals and with more prolonged supplementation (greater than 30 days). Personalized interventions with vitamin C may represent a feasible future strategy to enhance benefits and efficacy of interventions. Nevertheless, results need to be interpreted cautiously due to limitations in the primary studies.

Original title:
Effects of vitamin C supplementation on glycaemic control: a systematic review and meta-analysis of randomised controlled trials by Ashor AW, Werner AD, […], Siervo M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28294172

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Objectives:
Does magnesium supplementation reduce risk of cardiovascular disease among diabetic subjects?

Study design:
This review article included RCTs.

Results and conclusions:
The investigators found magnesium supplementation significantly improved fasting plasma glucose with 4.641 mg/dL [WMD = -4.641 mg/dL, 95% CI = -7.602 to -1.680, p = 0.002]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved high-density lipoprotein (HDL or good cholesterol) with 3.197 mg/dL [WMD = 3.197 mg/dL, 95% CI = 1.455 to 4.938, p 0.001]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved low-density lipoprotein (LDL or bad cholesterol) with 10.668 mg/dL [WMD = -10.668 mg/dL, 95% CI = -19.108 to -2.228, p = 0.013]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved plasma triglycerides with 15.323 mg/dL [WMD = -15.323 mg/dL, 95% CI = -28.821 to -1.826, p = 0.026]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved systolic blood pressure with 3.056 mmHg [WMD = 3.056 mmHg, 95% CI = -5.509 to -0.603, p = 0.015]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators concluded magnesium supplementation has a favourable effect on risk factors of cardiovascular diseases. Although future large RCTs are needed for making robust guidelines for clinical practice.

Original title:
Effect of magnesium supplementation on type 2 diabetes associated cardiovascular risk factors: a systematic review and meta-analysis by Verma H and Garg R.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28150351

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Objectives:
The conclusions from epidemiological studies are controversial between apple and pear consumption and type 2 diabetes mellitus (T2DM) risk. Therefore, this meta-analysis (systematic review) has been conducted.

Study design:
This review article included a total of 5 independent prospective cohort studies with 14,120 T2DM incident cases among 228,315 participants.

Results and conclusions:
The investigators found consumption of apples and pears was associated with 18% reduction in type 2 diabetes mellitus risk [multivariate-adjusted relative risk = 0.82, 95% CI = 0.75-0.88, I2 = 0.00%] when comparing the highest versus lowest category.

The investigators found dose-response analysis showed that one serving per week increment of apple and pear consumption was associated with a 3% [95% CI = 0.96-0.98, p for trend 0.001] reduction in type 2 diabetes mellitus risk.

The investigators concluded a higher consumption of apples and pears; at least one serving per week reduces type 2 diabetes mellitus risk.

Original title:
Apple and pear consumption and type 2 diabetes mellitus risk: a meta-analysis of prospective cohort studies by Guo XF, Yang B, […], Li D.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28186516

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The standard serving size is a 1/2 cup of sliced fruit. A medium pear produces approximately 1 cup of fruit; so an average medium pear equals two fruit servings.
1 small apple = 1 serving.
 

Objectives:
The association between serum folate and vitamin B12 levels and the risk of diabetic peripheral neuropathy (DPN) remains unclear. Therefore, this review article (meta-analysis) has been conducted.

Do reduced serum levels of folate and vitamin B12 increase peripheral neuropathy risk among patients with type 2 diabetes?

Study design:
This review article included 16 studies of serum folate levels (1190 patients with diabetic peripheral neuropathy and 1501 patients without diabetic peripheral neuropathy) and 18 studies of serum vitamin B12 levels (1239 patients with diabetic peripheral neuropathy and 1562 patients without diabetic peripheral neuropathy) in patients with type 2 diabetes mellitus (T2DM).

Results and conclusions:
The investigators found reduced serum levels of folate in patients with type 2 diabetes and diabetic peripheral neuropathy compared with patients with type 2 diabetes but without diabetic peripheral neuropathy [WMD = -1.64, 95% CI = -2.46 to -0.81].
A subgroup analysis confirmed this association in the Chinese population, but not in the Caucasian and mixed populations.

The investigators found reduced serum levels of vitamin B12 in patients with type 2 diabetes and diabetic peripheral neuropathy compared with patients with type 2 diabetes but without diabetic peripheral neuropathy [WMD = -70.86, 95% CI = -101.55 to -40.17].
A subgroup analysis confirmed this association in the Chinese population, but not in the Caucasian and mixed populations.

The investigators concluded reduced serum levels of folate and vitamin B12 increase peripheral neuropathy risk among patients with type 2 diabetes. These findings support the need for further controlled studies in defined patient populations and the importance of monitoring serum folate and vitamin B12 levels in patients with type 2 diabetes.

Original title:
Serum folate, vitamin B12 levels and diabetic peripheral neuropathy in type 2 diabetes: A meta-analysis by Wang D, Zhai JX and Liu DW.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28081987

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Diabetic peripheral neuropathy is a long-term complication of diabetes. Exposure to high blood glucose levels over an extended period of time causes damage to the peripheral nerves; the nerves that go to the arms, hands, legs and feet. It is one of many complications associated with diabetes, with nearly 60 percent of diabetics having some form of nerve damage.

Objectives:
Is there an association between individual micronutrients and blood pressure in patients with type 2 diabetes?

Study design:
This review article included 11 RCTs (13 interventions, 723 patients with type 2 diabetes and ages ranging from 50.7 to 66.8 years and 54% of them were males. The duration of diabetes varied from 4.6 to 8.6 years) with 3 to 52 weeks of follow-up were classified according to the type of micronutrient intervention: sodium (n = 1), vitamin C (n = 2), vitamin D (n = 7) and magnesium (n = 1).
Only a meta-analysis of vitamin C and D was able to perform with the available data.

Results and conclusions:
The investigators found vitamin C significantly reduced diastolic blood pressure of patients with type 2 diabetes with 2.88mmHg [WMD = -2.88 mmHg, 95% CI = -5.31 to -0.46, p = 0.020].
However, vitamin C not significantly reduced systolic blood pressure [WMD = -3.93mmHg, 95% CI = -14.78 to 6.92, p = 0.478].
Significant means that there is an association with a 95% confidence.

The investigators found vitamin D significantly reduced diastolic blood pressure of patients with type 2 diabetes with 2.44mmHg [WMD = -2.44 mmHg, 95% CI = -3.49 to -1.39, p  0.001].

The investigators found vitamin D significantly reduced systolic blood pressure of patients with type 2 diabetes with 4.56mmHg [WMD = -4.56 mmHg, 95% CI = -7.65 to -1.47, p = 0.004].

The investigators concluded vitamin D and possibly vitamin C have beneficial effects on blood pressure in patients with type 2 diabetes. Therefore, these interventions might represent a novel approach to the treatment of hypertension in patients with type 2 diabetes.

Original title:
Effects of individual micronutrients on blood pressure in patients with type 2 diabetes: a systematic review and meta-analysis of randomized clinical trials by de Paula TP, Kramer CK, [...], Azevedo MJ.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5233957/

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