Abstract
OBJECTIVES: Type 2 diabetes is accepted as a cause of heart failure, but direct cause-effect evidence independent of incident myocardial infarction (MI), hypertension and other coexisting risk factors is less well studied. We tested the hypothesis that diabetes predisposes to heart failure independently of hypertension and intercurrent MI. METHODS: We evaluated 12-year incident heart failure in 2740 participants (1781 women) without prevalent cardiovascular or severe kidney disease, at the time of the first exam of the Strong Heart Study cohort. Intercurrent MI was censored as a competing risk event. RESULTS: Diabetes was present in 1206 individuals (44%), and impaired fasting glucose (IFG) in 391 (14%). Diabetic participants more frequently had hypertension and/or central obesity (both P < 0.0001). Incident heart failure was ascertained in 64 participants with normal fasting glucose (NFG; 6%), 26 (7%) with IFG and 201 with diabetes (17%, hazard ratio = 4.04 vs. NFG, P < 0.0001). In Cox analysis adjusting for age, sex, obesity, central fat distribution, hypertension, antihypertensive medications, prevalent atrial fibrillation, glomerular filtration rate, urinary albumin/creatinine ratio, plasma cholesterol, Hb1Ac, smoking habit, alcohol use, educational level and physical activity, diabetes was associated with a two-fold greater risk of incident heart failure than NFG (hazard ratio = 2.45, P < 0.0001). Diabetes maintained 1.5-fold greater risk of heart failure than NFG (P < 0.03) even when intercurrent MI (n = 221) was censored as a competing risk event, similar to the adjusted hazard ratio for heart failure in hypertension. CONCLUSION: Type 2 diabetes is a potent, independent risk factor for heart failure. Risk of heart failure in diabetic patients cannot be fully explained by incident MI and coexisting cardiovascular risk factors. Mechanisms directly related to diabetes and impairing cardiac function should be studied and identified.