OBJECTIVE:

To evaluate the impact of oral magnesium supplementation on risk factors for end-organ disease in patients with non-insulin-dependent diabetes mellitus (NIDDM).

DESIGN:

A 16-week randomized, double-blind, placebo-controlled crossover trial.

SETTING:

Outpatient center of an academic family medicine residency program.

PATIENTS:

Twenty-eight patients (age range, 28 to 84 years; 57.1% black; 85.7% women) with NIDDM controlled by diet and/or an oral hypoglycemic, with a serum cholesterol levels over 5.20 mmol/L (200 mg/dL).

INTERVENTION:

Following a 2-week placebo run-in period, each patient was randomized to receive either sustained-release magnesium chloride (Slo-Mag), 384 mg/d, or an identical-appearing placebo for 6 weeks. After a 2-week interim washout period, each patient was then treated with the alternative regimen for an additional 6-week period.

MAIN OUTCOME MEASURES:

The systolic and diastolic blood pressure and levels of serum glucose, low-density and high-density lipoprotein and total cholesterol, triglycerides, and serum and total erythrocyte magnesium were measured at the beginning, midpoint, and end of each 6-week treatment phase.

RESULTS:

Systolic blood pressure fell an average of 7.4 mm Hg (P < .05) with treatment. There was no significant change in diastolic blood pressure or levels of serum glucose, low-density and high-density lipoprotein and total cholesterol, triglycerides, or serum and erythrocyte magnesium.

CONCLUSIONS:

Oral magnesium supplementation in the doses and duration studied is modestly effective in reducing systolic blood pressure in patients with NIDDM but has little impact on other important biochemical parameters related to diabetes-associated end-organ disease.