ABSTRACT
BACKGROUND@#The effects of l-arginine supplementation on indices of glycemic control and the role of many factors influencing this intervention have been controversial in clinical trials.@*OBJECTIVE@#This meta-analysis was performed to assess the effects of l-arginine supplementation on indices of glycemic control, including fasting blood glucose (FBG), hemoglobin A1c (HbA1c), serum insulin and homeostatic model assessment of insulin resistance (HOMA-IR) levels in randomized controlled trials (RCTs).@*SEARCH STRATEGY@#This study conducted a systematic review of RCTs published in PubMed, Scopus, Web of Science, Cochrane Library and Embase, up to 5 May, 2018.@*INCLUSION CRITERIA@#Studies were included in this meta-analysis if they were RCTs with parallel design and reported sufficient data on participants before and after intervention, and outcomes of glycemic profile parameters in both the arginine supplementation and control groups.@*DATA EXTRACTION AND ANALYSIS@#The screening of titles and abstracts was performed independently by two reviewers. Selected articles were considered if they met the study's inclusion criteria. The quality of included studies was assessed by using the Cochrane Collaboration modified tool. From 710 articles retrieved in the initial search, only 10 trials were suitable for pooling the effects of arginine supplementation on serum glucose, insulin, HOMA-IR and HbA1c levels, with effect sizes of nine, eight, five and five, respectively.@*RESULTS@#Pooled random-effect analysis revealed that l-arginine supplementation could significantly decrease FBG level (weighted mean difference [WMD]: 3.35 mg/dL; 95% confidence interval [CI] = [-6.55, -0.16]; P = 0.04) and serum insulin level (WMD: -2.19 μIU/mL; 95% CI = [-3.70, -0.67]; P = 0.005). However, the effects of l-arginine supplementation on HOMA-IR and HbA1c were not significant. Results of subgroup analysis showed that supplementation with l-arginine could significantly decrease serum insulin levels when the dosage of l-arginine is > 6.5 g/d (WMD: -3.49 μIU/mL; 95% CI = [-5.59, -1.38]; P = 0.001), when the duration of supplementation is ≤ 12.8 weeks (WMD: -3.76; 95% CI = [-6.50, -0.98]; P = 0.008), when the participants are not diabetic patients (WMD: -2.54 μIU/mL; 95% CI = [-4.50, -0.50]; P = 0.01) and when the baseline serum level of insulin was > 20 μIU/mL (WMD: -3.98; 95% CI = [-6.31, -1.65]; P = 0.001).@*CONCLUSION@#Although the results of this study confirmed that supplementation with l-arginine could have significant effects on some glycemic profile indices of participants in clinical trials, the clinical importance of this reduction may not be meaningful.
ABSTRACT
Introduction: Vitamin D as a common deficient micronutrient possibly plays an important role in body weight management. The aim of this study was to assess possible effects of vitamin D supplementation on anthropometric parameters of type-2 diabetic patients. Methods: Participants of this randomised controlled trial were 28 type-2 diabetic patients who received 4000 IU/day vitamin D and 30 patients who received placebo for two months. All patients were selected from the Iranian Diabetes Association (IDA), Tehran, Iran. Weight, height, body mass index, waist circumference, hip circumference and waist to hip ratio (WHR) were determined before and after the intervention. Dietary information was obtained using a 3-day food record. Results: Results showed a significant decrease in bodyweight (from 75.73±3.09 kg to 74.63±3.04 kg, p = 0.002), BMI (from 27.94±0.92 kg/m2 to 27.544±0.90 kg/m2, p = 0.001); waist circumference (from 92.56±2.33 cm to 91.05±2.27 cm, p = 0.004); and hip circumference (from 104.19±1.88 cm to 102.35±1.88 cm, p = 0.029) in the vitamin D group. Food record analysis showed that the percent of total calorie intake from dietary carbohydrates increased (from 50.40±1.38% to 53.14±1.53%, p = 0.023) and from fat, it decreased (from 38.43±1.30% to 35.22±1.49%, p = 0.011) significantly in the vitamin D group at the end of the intervention. Conclusion: Supplementation with vitamin D seems to include beneficial effects on bodyweight management in type-2 diabetic patients. However, the percentage of total calorie intake from each macronutrient should be