Contemporary risk estimates of three HbA_1c variables in relation to heart failure following diagnosis of type 2 diabetes.

Abstract

We evaluated the association between glycaemic control and the risk of heart failure (HF) in a contemporary cohort of persons followed after diagnosis of type 2 diabetes (T2D). Persons with T2D diagnosed between 1998 and 2012 were retrieved from the Clinical Practice Research Data Link in the UK and followed from diagnosis until the event of HF, mortality, drop out from the database due to any other reason, or the end of the study on 1 July 2015. The association between each of three different haemoglobin A_1C (HbA_1c) metrics and HF was estimated using adjusted proportional hazard models. In the overall cohort (n=94 332), the increased risk for HF per 1% (10 mmol/mol) increase in HbA_1c was 1.15 (95% CI 1.13 to 1.18) for updated mean HbA_1c, and 1.06 (1.04 to 1.07) and 1.06 (1.04 to 1.08) for baseline HbA_1c and updated latest HbA_1c, respectively. When categorised, the hazard risk (HR) for the updated mean HbA_1c in relation to HF became higher than for baseline and updated latest HbA_1c above HbA_1c levels of 9%, but did not differ at lower HbA_1c levels. The updated latest variable showed an increased risk for HbA_1c <6% (42 mmol/mol) of 1.16 (1.07 to 1.25), relative category 6-7%, while the HRs for updated mean and baseline HbA_1c showed no such J-shaped pattern. Hyperglycaemia is still a risk factor for HF in persons with T2D of similar magnitude as in earlier cohorts. Such a relationship exists for current glycaemic levels, at diagnosis and the overall level but the pattern differs for these variables.