The effect of oral magnesium supplementation on glycemic control and metabolic parameters in type 2 diabetes mellitus: a double-blind randomized controlled trial.

Background: This randomized controlled trial (RCT) assessed the effect of oral magnesium (Mg) supplementation on glycated hemoglobin (HbA1c) and metabolic biomarkers in adults with Type 2 Diabetes Mellitus (T2DM). Methods: This was a prospective, randomized, double-blind, placebo-controlled, parallel-group clinical trial with intention-to-treat (ITT) and per-protocol (PP) analyses. Adults (≥18 years) with T2DM were randomized 1:1 to receive magnesium oxide (500 mg; 302 mg elemental) or placebo. Eligibility criteria included a glycated hemoglobin (HbA1c) level ≥7.0% and a creatinine clearance >30 mL/min. Simple randomization was performed using a sealed-envelope method. Biochemical and clinical parameters were assessed at baseline and at three follow-up visits over 12 months. Results: A total of 247 participants were included in the ITT analysis (Mg-oxide, n=118; placebo, n=129). Median age was 58 (50-65) years, and median diabetes duration was 16 (10-22) years. Hypomagnesemia was present in 7.3% by ionized magnesium (iMg) and 8.1% by total magnesium (tMg). Mg-oxide supplementation significantly reduced fasting blood glucose in a subgroup of the cohort (FBG; Conclusions: Although median HbA1c reduction did not reach statistical significance, Mg-oxide supplementation improved Mg status and showed favorable trends in glycemic control without compromising safety. These findings support Mg supplementation as a safe adjunct to long-term T2DM management, particularly among selected subgroups, given the study's limitations. Clinical Ttrial Registration: https://clinicaltrials.gov/, identifier NCTO5774015.