Results:

A total of 20,985 patients were included (mean age 38.6 years, 45% women). Over a median follow-up of 9 years, 635 patients were admitted to the hospital with a primary or secondary diagnosis of heart failure, which was an incidence of 3.38 events per 1,000 patients-years (95% confidence interval [CI], 3.12-3.65). Incidence increased with HbA_1c, with a range of 1.42-5.20 per 1,000 patient-years between patients in the lowest (<6.5%) and highest (≥10.5%) categories of HbA_1c. After adjustment for age, sex, duration of diabetes, cardiovascular risk factors, and baseline or intervening acute myocardial infarction and other comorbidities, the risk for development of heart failure was 3.98 (95% CI, 2.23-7.14) for patients with an HbA_1c of 10.5% or higher as compared to patients with an HbA_1c of <6.5%. Risk of heart failure increased with age and duration of diabetes. Other modifiable factors associated with increased risk of heart failure were smoking, high systolic blood pressure, and raised body mass index. In a subgroup of 18,281 patients (87%) with data for blood lipids, higher high-density lipoprotein cholesterol was associated with lower risk of heart failure, but there was no association with low-density lipoprotein cholesterol.