Study
The effect of oral magnesium supplementation on glycemic control and metabolic parameters in type 2 diabetes mellitus: a double-blind randomized controlled trial.
In 247 adults with type 2 diabetes, 12 months of magnesium oxide did not significantly reduce HbA1c versus placebo.
Summary Does taking magnesium improve blood sugar control in type 2 diabetes? Show / hide ↓
Researchers randomly assigned 247 adults with type 2 diabetes to take magnesium oxide, a magnesium supplement, or an inactive look-alike pill for 12 months. Neither the participants nor the researchers knew who received which treatment until the study ended. HbA1c, a measure of average blood sugar over the previous two to three months, fell slightly more with magnesium, but the difference was not clear enough to rule out chance. Magnesium improved blood magnesium levels and lowered fasting blood glucose, blood sugar measured after not eating overnight, in some participants, but it did not improve other measures overall.
What this means for you: This study does not show that magnesium reliably improves long-term blood sugar control. Do not buy magnesium for diabetes based on this result alone, unless a healthcare professional has identified low magnesium or another reason to use it.
moderate evidenceThis 12-month randomised, double-blind, placebo-controlled trial evaluated magnesium oxide in adults with type 2 diabetes, HbA1c at least 7.0%, and creatinine clearance above 30 mL/min. The 247 participants in the intention-to-treat analysis received magnesium oxide 500 mg, providing 302 mg elemental magnesium (n=118), or placebo (n=129). Median age was 58 years and median diabetes duration was 16 years. Only 7.3% had low ionised magnesium and 8.1% had low total magnesium at baseline. Magnesium oxide improved magnesium status and lowered fasting blood glucose in a subgroup (p=0.039). The HbA1c change was -0.30% with magnesium oxide versus -0.05% with placebo, which was not statistically significant (p=0.145). A higher proportion achieved controlled HbA1c (p=0.043). Signals were larger in people with baseline hypomagnesemia or diabetes duration of 15 years or less, but those comparisons did not reach conventional statistical significance. No differences were reported in other metabolic parameters, clinical outcomes or adverse drug reactions. The primary glycaemic result was therefore a favourable trend, not definitive evidence of improved long-term diabetes control.
Magnesium oxide improved magnesium status and showed favourable but non-significant trends in glycaemic control without compromising safety.
This was a type 2 diabetes population, not healthy adults, and HbA1c reduction versus placebo was not statistically significant. Most participants were not hypomagnesemic at baseline, while the more favourable findings were subgroup signals.
Cited by
1 encyclopedia entries reference this study.