A Vanderbilt study examining the impact of the two most commonly prescribed oral diabetes medications on the risk for heart attack, stroke and death has found the drug metformin has benefits over sulfonylurea drugs.

It was important to examine the cardiovascular impact of the more commonly used diabetes drugs after recent controversy surrounded another diabetes medication, rosiglitazone, because it was associated with an increased cardiac risk, said lead author, Christianne L. Roumie, M.D., MPH, assistant professor of Internal Medicine and Pediatrics. Smaller studies pointed to a potential advantage of taking the drug metformin but this study confirms this in a large population.

"We demonstrated that for every 1,000 patients who are using metformin for a year there are two fewer heart attacks, strokes or deaths compared with patients who use sulfonylureas. I think this reinforces the recommendation that metformin should be used as the first medication to treat diabetes," Roumie said.

The researchers looked at the charts of more than 250,000 veterans receiving care in Veterans Health Administration hospitals throughout the United States. The patients were started on oral therapy for their diabetes with either metformin or a sulfonylurea and followed for about a year. Results are in the Nov. 6 issue of Annals of Internal Medicine.

"Both drugs do a good job helping control diabetes and preventing nerve damage and eye disease associated with high sugar levels. We did this study because there was an important knowledge gap about whether metformin was superior to sulfonylureas for prevention of heart disease, stroke and death," said senior author Marie R. Griffin M.D., MPH, professor of Preventive Medicine.

The limitations of the study include that neither patient group was compared with diabetic patients who take no oral medications, and that the veteran patients were mostly men.

Metformin is already the recommended first-line therapy for those needing oral medication to control type 2 diabetes. The most common side effect is stomach upset, which can often be overcome by titrating the dosage up slowly. It has not been recommended that patients with kidney impairment take metformin, so sulfonylureas might be a better choice for those patients.

Roumie said this study suggests it might be prudent to take a second look at those patients who have been taking sulfonylureas to see if a switch to metformin might be recommended.

The study was funded by the Agency for Healthcare Research and Quality and the U.S. Department of Health and Human Services.