Metformin and Thiazolidinedione Use in Medicare Patients With Heart Failure

CONTEXT: According to package inserts, metformin is contraindicated in diabetic patients receiving drug treatment for heart failure therapy, and thiazolidinediones are not recommended in diabetic patients with symptoms of advanced heart failure. Little is known about patterns of use of these antihyperglycemic drugs in diabetic patients with heart failure. OBJECTIVE: To determine the proportions of patients hospitalized with heart failure and concomitant diabetes treated with metformin or thiazolidinediones. DESIGN: Serial cross-sectional measurements using data from retrospective medical record abstraction. SETTING: Nongovernmental acute care hospitals in the United States. PATIENTS: Two nationally representative samples of Medicare beneficiaries hospitalized with the primary diagnosis of heart failure and concomitant diabetes between April 1998 and March 1999 and between July 2000 and June 2001. MAIN OUTCOME MEASURES: The prescription of either metformin or a thiazolidinedione at hospital discharge. RESULTS: In the 1998-1999 sample (n = 12 505), 7.1% of patients were discharged with a prescription for metformin, 7.2% with a prescription for a thiazolidinedione, and 13.5% with a prescription for either drug. In the 2000-2001 sample (n = 13 158), metformin use increased to 11.2%, thiazolidinedione use to 16.1%, and use of either drug to 24.4% (P<.001 for all comparisons). Similar increases were seen among patients of all age groups, all races, and both sexes. CONCLUSIONS: The use of metformin and thiazolidinediones is common and has increased rapidly in Medicare beneficiaries with diabetes and heart failure in direct contrast with explicit warnings against this practice by the Food and Drug Administration. Further studies to establish the safety and effectiveness of this practice are needed to ensure optimal care of patients with diabetes and heart failure.