The effects of oral magnesium supplementation on glycaemic control in patients with type 2 diabetes: a systematic review and dose-response meta-analysis of controlled clinical trials.

The current systematic review and meta-analysis were conducted to evaluate the effects of oral Mg supplementation on glycaemic control in type 2 diabetes mellitus (T2DM) patients. Related articles were found by searching the PubMed, SCOPUS, Embase and Web of Science databases (from inception to 30 February 2020). A one-stage robust error meta-regression model based on inverse variance weighted least squares regression and cluster robust error variances was used for the dose-response analysis between Mg supplementation and duration of intervention and glycaemic control factors. Eighteen eligible randomised clinical trials were included in our final analysis. The dose-response testing indicated that the estimated mean difference in HbA1c at 500 mg/d was -0·73 % (95 % CI: -1·25, -0·22) suggesting modest improvement in HbA1c with strong evidence (P value: 0·004). And in fasting blood sugar (FBS) at 360 mg/d was -7·11 mg/dl (95 % CI: -14·03, -0·19) suggesting minimal amelioration in FBS with weak evidence (P value: 0·092) against the model hypothesis at this sample size. The estimated mean difference in FBS and HbA1c at 24 weeks was -15·58 mg/dl (95 % CI: -24·67, -6·49) and -0·48 (95 % CI: -0·77, -0·19), respectively, suggesting modest improvement in FBS (P value: 0·034) and HbA1c (P value: 0·001) with strong evidence against the model hypothesis at this sample size. Oral Mg supplementation could have an effect on glycaemic control in T2DM patients. However, the clinical trials so far are not sufficient to make guidelines for clinical practice.