Issue 139 Item 9 Metformin Linked to Reduced Risk of Mortality

When treatment with metformin was compared to sulfonylurea treatment, study showed a 24.7%, reduction. >In a retrospective population-based cohort study, treatment with metformin, alone or in combination with sulfonylurea, was associated with a decreased risk of mortality compared with sulfonylurea monotherapy.

"Our results refute previous epidemiologic studies suggesting that metformin is associated with increased mortality in type 2 diabetics," Canadian researchers write in the December issue of Diabetes Care.

Dr. Jeffrey A. Johnson and colleagues from the University of Alberta in Edmonton analyzed mortality in 3033 and 1150 "new users" of sulfonylurea or metformin, respectively, as well as 4683 new users of both agents. They defined new users as individuals with prescriptions for sulfonylurea or metformin between 1991 and 1996 and no use in the prior year.

During an average follow-up of 5.1 years, mortality rates among subjects with at least 1 year of drug exposure and no insulin use were 24.7%, 13.8%, and 13.6% for subjects taking sulfonylurea monotherapy, metformin monotherapy and combination therapy, respectively.

Compared with sulfonylurea monotherapy, the adjusted odds ratio for all-cause mortality for metformin monotherapy was 0.60, the team reports. "Sulfonylurea plus metformin combination therapy was also associated with reduced all-cause mortality," they report, with an odds ratio of 0.66.

The data suggest a reduction in cardiovascular-related mortality rates in metformin users compared with sulfonylurea users.

Dr. Johnson and colleagues suggest in their report that previous studies linking metformin use to increased mortality risk did not have sufficient numbers of subjects or events to evaluate mortality adequately. Diabetes Care 2002;25:2244-2248.