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Few data are available on the effect of sulfonylureas and metformin on adverse cardiovascular (CV) outcomes among patients with type 2 diabetes. Using a Veterans Health Administration database, researchers identified 254,000 patients (primarily white men) who began metformin or sulfonylurea monotherapy between 2001 and 2008. Patients were followed until another antidiabetic agent was prescribed or a primary outcome (death or hospitalization for myocardial infarction or stroke) was reached. Patients with serious medical conditions (e.g., heart failure, HIV infection) or creatinine levels ≥1.5 mg/dL were excluded.
Unadjusted rates of the primary outcome were 18.2 per 1000 person-years among sulfonylurea recipients and 10.4 per 1000 person-years among metformin recipients. After adjusting for potential confounders, 2.2 more adverse CV events or deaths per 1000 person-years occurred with sulfonylurea than with metformin. Results did not differ by type of sulfonylurea (glyburide or glipizide).
Roumie CL et al. Comparative effectiveness of sulfonylurea and metformin monotherapy on cardiovascular events in type 2 diabetes mellitus: A cohort study. Ann Intern Med 2012 Nov 6; 157:601. (http://annals.org/article.aspx?articleid=1389845)
Comment
In this retrospective study, use of sulfonylureas as initial monotherapy for patients with type 2 diabetes was associated with higher risk for adverse CV events than was metformin. Whether the difference arose from excess CV risk with sulfonylureas, lower risk with metformin, or both is unclear. In addition, adjustment for confounding factors narrowed the difference in adverse outcomes substantially, raising concern that additional unmeasured confounders influenced these findings. Nevertheless, the results are consistent with metformin's current status as the initial agent of choice for type 2 diabetes.