Effect of chromium supplementation on glycated hemoglobin and fasting plasma glucose in patients with diabetes mellitus

Aims: Chromium (Cr) is a trace element involved in glucose homeostasis. We aim to evaluate and quantify the effects of Cr supplementation on A1C and FPG in patients with T2DM. Materials and methods: A systematic literature search of Pubmed, EMBASE and the Cochrane Library (from database inception to 11/2014) with no language restrictions sought RCTs or cohort studies evaluating Cr supplementation in T2DM vs control and reporting either change in glycated hemoglobin (A1C) or fasting plasma glucose (FPG). Meta-analysis was conducted on each subtype of Cr supplement separately, and was analyzed by random effects model to yield the weighted mean differences (WMD) and 95% confidence intervals (CIs). Heterogeneity was assessed by using the I-2 statistic. Results: A total of 14 RCTs (n=875 participants, mean age range: 30 to 83 years old, 8 to 24 weeks of follow-up) were identified (Cr chloride: n=3 study, Cr picolinate: n=5 study, brewer's yeast: n=4 study and Cr yeast: n=3 study). Compared with placebo, Cr yeast, brewer's yeast and Cr picolinate did not show statistically significant effects on A1C. Furthermore, compared to control, Cr chloride, Cr yeast and Cr picolinate showed no effect on FPG, however, brewer's yeast showed a statistically significant decrease in FPG -19.23 mg/dL (95% CI=-35.30 to -3.16, I-2=21%, n=137). Conclusions: Cr supplementation with brewer's yeast may provide marginal benefits in lowering FPG in patients with T2DM compared to placebo however it did not have any effect on A1C.