The effects of combined magnesium and zinc supplementation on metabolic status in patients with type 2 diabetes mellitus and coronary heart disease

Randomized, placebo-controlled, 12-week trial conducted at a cardiology clinic affiliated with Kashan University of Medical Sciences in Kashan, Iran. Adults with type 2 diabetes mellitus and proven 2- and 3-vessel coronary heart disease were enrolled; the magnesium plus zinc arm had 30 randomized participants, with 27 reported in the trial table, and all participants were women.

Magnesium plus zinc co-supplementation consisted of magnesium oxide 250 mg/day plus zinc sulfate 150 mg/day, providing 30 mg elemental zinc, taken daily for 12 weeks. The active regimen was compared with placebo.

Magnesium plus zinc supplementation improved several metabolic, inflammatory, oxidative stress, and mood outcomes versus placebo over 12 weeks. Compared with placebo, fasting plasma glucose fell by 9.44 mg/dL (95% CI -18.30, -0.57; P = 0.03), insulin by 1.37 μIU/mL (95% CI -2.57, -0.18; P = 0.02), HDL-cholesterol increased by 2.09 (95% CI 0.05, 4.13; P = 0.04), CRP decreased by 0.85 (95% CI -1.26, -0.45; P < 0.001), total nitrite increased by 5.13 (95% CI 1.85, 8.41; P = 0.003), and total antioxidant capacity increased by 43.44 (95% CI 3.39, 83.50; P = 0.03). Beck Depression Inventory and Beck Anxiety Inventory scores also improved, while several lipid and insulin resistance indices were not significant; no adverse effects were reported in the magnesium plus zinc group.

The trial was small, single-center, and short in duration, which limits certainty about long-term efficacy and safety. The sample was restricted to women with type 2 diabetes and coronary heart disease, reducing generalizability, and several prespecified metabolic outcomes did not change significantly.