Metformin therapy and outcomes in patients with advanced systolic heart failure and diabetes.

Although 25% to 44% of patients with heart failure (HF) have diabetes mellitus (DM), the optimal treatment regimen for HF patients with DM is uncertain. We investigated the association between metformin therapy and outcomes in a cohort of advanced, systolic HF patients with DM. Patients with DM and advanced, systolic HF (n = 401) were followed at a single university HF center between 1994 and 2008. The cohort was divided into 2 groups based on the presence or absence of metformin therapy. The cohort had a mean age of 56 +/- 11 years, left ventricular ejection fraction (LVEF) of 24 +/- 7%, with 42% being New York Heart Association (NYHA) III and 45% NYHA IV. Twenty-five percent (n = 99) were treated with metformin therapy. The groups treated and not treated with metformin were similar in terms of age, sex, baseline LVEF, medical history, and baseline glycosylated hemoglobin. Metformin-treated patients had a higher body mass index, lower creatinine, and were less often on insulin. One-year survival in metformin-treated and non-metformin-treated patients was 91% and 76%, respectively (RR = 0.37, CI 0.18-0.76, P = .007). After multivariate adjustment for demographics, cardiac function, renal function, and HF medications, metformin therapy was associated with a nonsignificant trend for improved survival. In patients with DM and advanced, systolic HF who are closely monitored, metformin therapy appears to be safe. Prospective studies are needed to determine whether metformin can improve HF outcome.