Glycaemic control and excess risk of major coronary events in persons with type 1 diabetes

Objective The excess risk of major coronary events (acute myocardial infarction (AMI) or death from coronary heart disease (CHD)) in individuals with type 1 diabetes (T1D) in relation to glycaemic control and renal complications is not known. Methods Individuals with T1D in the Swedish National Diabetes Registry after 1 January 1998, without a previous MI (n=33 170) and 1 64 698 controls matched on age, sex and county were followed with respect to non-fatal AMI or death from CHD. Data were censored at death due to any cause until 31 December 2011. Results During median follow-up of 8.3 and 8.9 years for individuals with T1D and controls, respectively, 1500 (4.5%) and 1925 (1.2%), experienced non-fatal AMI or died from CHD, adjusted HR 4.07 (95% CI 3.79 to 4.36). This excess risk increased with younger age, female sex, worse glycaemic control and severity of renal complications. The adjusted HR in men with T1D with updated mean haemoglobin A1c (HbA1c) < 6.9% (52 mmol/mol) and normoalbuminuria was 1.30 (95% CI 0.90 to 1.88) and in women 3.16 (95% CI 2.14 to 4.65). HRs increased to 10.7 (95% CI 8.0 to 14.3) and 31.8 (95% CI 23.6 to 42.8) in men and women, respectively, with HbA1c >9.7% and renal complications. Conclusions The excess risk of AMI in T1D is substantially lower with good glycaemic control, absence of renal complications and men compared with women. In women, the excess risk of AMI or CHD death persists even among patients with good glycaemic control and no renal complications.