Glycaemic Control and Incidence of Heart Failure in 20,985 Patients With Type 1 diabetes: An Observational Study

Study Questions:

Is poor glycemic control associated with increased risk for heart failure?

Methods:

Data from the Swedish national diabetes registry were used for the present study. All patients over the age of 17 years with type 1 diabetes who were registered in the national diabetes registry between January 1998 and December 2003 were included. Subjects with a prior history of heart failure at baseline were excluded. Categories of glycated hemoglobin (HbA1c) were primary exposure of interest, and the primary outcome of heart failure was examined by these categories.

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 HbA1c, 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 HbA1c. 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 HbA1c of 10.5% or higher as compared to patients with an HbA1c 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.

Conclusions:

The investigators concluded that a positive association between HbA1c and risk of heart failure in fairly young patients with type 1 diabetes indicates a potential for prevention of heart failure with improved glycemic control.

Perspective:

This study, using data from a large-scale registry, suggests an increased risk of heart failure among type 1 diabetics with poor glucose control. It remains to be determined if interventions that improve glucose control reduce risk for heart failure.

Clinical Topics: Dyslipidemia, Heart Failure and Cardiomyopathies, Prevention, Lipid Metabolism, Nonstatins, Acute Heart Failure, Smoking

Keywords: Myocardial Infarction, Hyperglycemia, Follow-Up Studies, Comorbidity, Risk Factors, Blood Pressure, Smoking, Hemoglobin A, Glycosylated, Heart Diseases, Incidence, Cholesterol, Registries, Body Mass Index, Blood Glucose, Heart Failure, Confidence Intervals, Diabetes Mellitus, Type 1, Diabetes Mellitus


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