ADA 2010: Metformin associated with lower risk of mortality than other oral antidiabetic agents in patients with diabetes and heart failure

In patients with diabetes and concomitant heart failure who are naive to oral antidiabetic drugs, the introduction of metformin use is associated with a lower risk of mortality than the introduction of other oral antidiabetic drugs, found Dean T Eurich, PhD.

In a nested, case-control study, the records of patients 35 years or older who were newly diagnosed with both heart failure and diabetes after January 1988 and who died before October 2007 were selected from the UK General Practice Research Database.

Controls were matched to cases on the basis of age, sex, clinic site, calendar year, and duration of follow-up. Analyses were adjusted for comorbidities, glycated hemoglobin values, renal function, body mass index, hemoglobin, blood pressure, and drug therapies known to affect outcomes in patients with diabetes and heart failure.

There were 1,633 cases and 1,633 controls (mean age, 78 years). Compared with patients whose diabetes was controlled solely by diet and lifestyle, the use of metformin was associated with an adjusted 34% reduction in mortality on multivariate analyses (P=.006), whereas the use of other antidiabetic drugs or insulin was not associated with all-cause mortality.

The use of angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs; 45% reduction) and beta-blockers (24% reduction) were also associated with lower mortality.

By including only patients not previously exposed to antidiabetic drugs, “our results suggest that the apparent benefit of metformin over other antidiabetic agents is due to reduced mortality risk with metformin rather than harm with other agents,” according to Eurich, assistant professor, Department of Public Health Sciences, School of Public Health, University of Alberta, Edmonton, Alberta.

“Until randomized trial evidence becomes available, we believe that our study and the extant published literature support the use of metformin-based strategies for glucose-lowering in patients with diabetes and heart failure," he said.

He added that underuse of proven effective therapies in this group of patients is common, as evidenced by the low rate of the use of both ACE inhibitors or ARBs and beta blockers (18%) in the study population.