Effects of chromium supplementation on glycemic control in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND: We aimed to investigate the effect of chromium supplementation on glycemic control indices in patients with type 2 diabetes (T2DM). METHODS: Randomized controlled trials examining the effect of chromium supplementation on glycemic control indices and published before February 2020 were detected by searching online databases, including PubMed, Scopus, Embase, Web of sciences and The Cochrane Library, using a combination of suitable keywords. Mean change and standard deviation (SD) of the outcome measures were used to estimate the mean difference between the supplementation group and the control group at follow-up. RESULTS: Twenty-eight studies reported fasting plasma glucose (FPG), insulin, hemoglobin Al C (HbA1C) and homeostatic model assessment for insulin resistance (HOMA-IR) as an outcome measure. Results revealed significant reduction in FPG (weighted mean difference (WMD): -19.00 mg/dl, 95% CI: -36.15, -1.85, P = 0.030; I-2: 99.8%, p < 0.001), insulin level (WMD: -12.35 pmol/l, 95% CI: -17.86, -6.83, P < 0.001), HbA1C (WMD: -0.71 %, 95% CI: -1.19, -0.23, P = 0.004) and HOMA-IR (WMD: -1.53, 95% CI: -2.35, -0.72, P < 0.001; I-2: 89.9%, p < 0.001) after chromium supplementation. Conclusion: The results of the current meta-analysis study might support the use of chromium supplementation for the improvement of glycemic control indices in T2DM patients.