The relationship between glycaemic control and heart failure in 83,021 patients with type 2 diabetes.

AIMS/HYPOTHESIS: The aim of this study was to examine the relationship between glycaemic control and hospitalisation for heart failure in patients with type 2 diabetes.

METHODS: Patients included in the Swedish National Diabetes Register (NDR) during 1998-2003 were followed until hospitalisation for heart failure, death or 31 December 2009. Unadjusted and adjusted incidence rates for heart failure were estimated by Poisson regression and relative risk was estimated by Cox regression.

RESULTS: In 83,021 patients with type 2 diabetes, 10,969 (13.2%) were hospitalised with a primary or secondary diagnosis of heart failure during a mean follow-up of 7.2 years. The incidence increased by male sex (p < 0.001), older age (p < 0.001) and longer diabetes duration (p < 0.001). In Cox regression adjusting for risk factors of heart failure the HR per each percentage unit higher HbA(1c) (10 mmol/mol) for heart-failure hospitalisation was 1.12 (95% CI 1.10, 1.14). By category of HbA(1c) the HR for heart failure hospitalisation was: HbA(1c) 6.0 to <7.0% (42 to <53 mmol/mol), 0.91 (95% CI 0.84, 0.98); HbA(1c) 7.0 to <8.0% (53 to <64 mmol/mol), 0.99 (95% CI 0.91, 1.07); HbA(1c) 8.0 to <9.0% (64 to < 75 mmol/mol), 1.10 (95% CI 1.01, 1.20); HbA(1c) 9.0 to <10.0% (75 to <86 mmol/mol), 1.27 (95% CI 1.15, 1.41); HbA(1c) ≥ 10.0 % (≥ 86 mmol/mol), 1.71 (1.51, 1.93) (reference HbA(1c) <6% [42 mmol/mol]). The HR for patients with HbA(1c) 7.0 to <8.0% (53 to < 64 mmol/mol) compared with patients with HbA(1c) 6.0 to <7.0% (42 to <53 mmol/mol) was 1.09 (95% CI 1.03, 1.14).

CONCLUSIONS/INTERPRETATION: Poor glycaemic control (HbA(1c) >7% [53 mmol/mol]) is associated with an increased risk of hospitalisation for heart failure in patients with type 2 diabetes.