Does magnesium affect blood sugar?

Slightly. A 2021 review of double-blind trials found that magnesium lowered fasting glucose in people with diabetes. In people at high risk, it improved glucose and insulin sensitivity.^[1] In a 2026 review of 78 trials, fasting glucose was 3.60 mg/dL lower and HbA1c 0.15 percentage points lower. The authors called the effects modest.^[2]

A 2016 review found a clear drop in fasting glucose only in trials that lasted 4 months or longer.^[3] Single trials disagree. In people with type 2 diabetes and low blood magnesium, 300 mg a day as magnesium chloride for 16 weeks lowered glucose and HbA1c. In 50 people with type 2 diabetes on insulin, 369 mg a day as magnesium aspartate for 3 months did not change blood sugar control.^[4]

The American Diabetes Association says the evidence is not enough to recommend magnesium for blood sugar control.^[4] People who take diabetes medicines should ask a doctor or pharmacist first.^[4]