Metformin May Not Benefit Non-Diabetic Heart Patients

Although metformin has been shown to reduce cardiovascular risk in patients with type 2 diabetes mellitus, new research finds that the drug may not offer the same protective benefits in those without diabetes.

The study, published online on November 7, 2013, in The Lancet Diabetes & Endocrinology, randomly assigned 173 patients—who had coronary heart disease and large waist circumferences, were taking statins, and did not have diabetes—to take metformin 850 mg or placebo twice daily.

The researchers measured the progression of mean distal carotid intima-media thickness, changes in carotid plaque scores, measures of glycemia, and concentration of lipids.

After 18 months, carotid intima-media thickness progressed similarly among patients in the metformin and placebo groups. There was no significant difference in changes in carotid plaque scores between the groups as well. Total cholesterol, high-density lipoprotein (HDL)—cholesterol, non-HDL-cholesterol, triglycerides, and fasting glucose levels also did not differ significantly between patients assigned to metformin and those assigned to placebo. Patients taking metformin did, however, have significantly lower glycated hemoglobin and insulin levels compared with those taking the placebo. Diarrhea, nausea, and vomiting were more common among the metformin group than the placebo group.

The study was limited by a small sample size and short follow-up, and the researchers suggest that larger studies are needed to confirm the results.