Issue 112 Item 6 ADA: Metformin Decreases Cardiovascular Events in Diabetics

Metformin monotherapy results in fewer fatal and non-fatal cardiovascular (CV) events compared to sulfonylurea monotherapy in new users of these agents. Said, investigators said at the 62nd Scientific Sessions of the American Diabetes Association (ADA).

Dr. Jeffrey A. Johnson with the University of Alberta in Edmonton, Canada, and colleagues used Databases of Saskatchewan Health to identify new users of oral antidiabetic agents, described as those with prescriptions for a sulfonylurea agent or metformin in 1991 to 1996 who had not used these agents in the prior 12 months.

The researchers defined CV events as any hospitalization or death during the follow-up period, which extended up to nine years. Causes of death or hospitalization were identified based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). They used multivariate logistic regression analysis to assess the differences between drug cohorts, after adjusting for potential confounding variables

The total study sample comprised 8,866 new users of oral antidiabetic agents with at least one year of drug exposure and no insulin use, who were followed for an average of 5.3 years.

A CV-related event occurred in 1,216 of 3,034 (40.1 percent) subjects on sulfonylurea monotherapy, in 351 of 1,150 (30.5 percent) on metformin monotherapy, and in 1,733 of 4,682 (37.0 percent) on combination therapy.

Deaths due to CV causes were significantly lower in patients treated with metformin alone or in combination compared to the sulfonyurea monotherapy cohort.

The number of non-fatal hospital admissions for CV-related diagnoses was significantly lower in the metformin monotherapy cohort but the combination therapy cohort was not significantly different compared to the sulfonylurea monotherapy group.

The adjusted odds ratios for a CV-related event were 0.79 and 0.98 for metformin and combination therapy, respectively, compared to sulfonylurea monotherapy. .

Dr. Johnson cautioned that the study is limited by the fact that information for this analysis was taken from administrative databases and thus does not contain clinical data.

Another possible limitation involves the study’s retrospective design. "As with any study using retrospective data, the observations depend on the accuracy and completeness of the records," Dr. Johnson said. "However, the Saskatchewan Health databases are recognized internationally for their accuracy and comprehensiveness of health care data for all residents of Saskatchewan."

Overall, observations from this cohort of new users of oral antidiabetic agents indicate that metformin is safe as either monotherapy or in combination with sulfonylureas, Dr. Johnson said. In addition, the use of metformin may be associated with reduced CV mortality in people with type 2 diabetes.

62nd Scientific Sessions of the American Diabetes Association (ADA).