Effects of L-arginine supplementation on biomarkers of glycemic control: a systematic review and meta-analysis of randomised clinical trials

The present meta-analysis aimed to determine the effectiveness of L-arginine supplementation in improving biomarkers of glycemic control in adults. Electronic databases including PubMed, ISI Web of Science, Scopus, and the Cochrane Collaboration Library were searched up to January 2020. The meta-analysis of twelve randomised clinical trials indicated that L-arginine had no significant effect on serum fasting blood sugar (FBS) (weighted mean difference [WMD]: -3.38 mg/dl, 95% CI: -6.79 to 0.04, p = .53), serum insulin (WMD: -0.12 Hedges' g 95% CI: -0.33 to 0.09, p = .27), glycated haemoglobin A1c (HbA1c; WMD: -0.04%, 95% CI: -0.25 to 0.17, p = .71), and homeostasis model assessment for insulin resistance (WMD: -0.48, 95% CI: -1.15 to 0.19, p = .15). Although several animal studies have proposed that L-arginine supplementation might improve blood glucose control, the present study could not confirm this benefit in humans.