Glycemic Control and Risk of Coronary Events in Type 1 Diabetes
What is the relationship between glycemic control and renal complications in type 1 diabetics (T1D) and major coronary events (acute myocardial infarction [AMI] or death from coronary heart disease [CHD])?
Individuals with T1D in the Swedish National Diabetes Registry after January 1, 1998, without a previous MI (n = 33,170) and 164,698 controls matched on age, sex, and county were followed with respect to nonfatal AMI or death from CHD. Data were censored at death due to any cause until December 31, 2011.
In patients with T1D, mean value for age was 35.2 years, hemoglobin A1c (HbA1c) was 8.2%, diabetes duration was 20.0 years, body mass index was 25.0 kg/m2, blood pressure was 126.7/73.6 mm Hg, and 86.4% were nonsmokers. During median follow-up of 8.3 and 8.9 years for individuals with T1D and controls, respectively, 1,500 (4.5%) and 1,925 (1.2%), experienced nonfatal AMI or died from CHD (adjusted hazard ratio [HR], 4.07; 95% confidence interval [CI], 3.79-4.36). This excess risk increased with younger age, female sex, worse glycemic control, and severity of renal complications. The adjusted HR in men with T1D with updated mean HbA1c <6.9% and normoalbuminuria was 1.30 (95% CI, 0.90-1.88) and in women was 3.16 (95% CI, 2.14-4.65). HRs increased to 10.7 (95% CI, 8.0-14.3) and 31.8 (95% CI, 23.6-42.8) in men and women, respectively, with HbA1c >9.7% and renal complications.
The excess risk of AMI in T1D is substantially lower with good glycemic 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 glycemic control and no renal complications.
The absolute cardiovascular event rates are low because of the young age, but would likely be lower with appropriate use of statins and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in the T1D cohort (about 25% for each). The marked increase in cardiovascular events in women compared with men (two-fold) in T1D is not understood. Men with T1D with good glycemic control and normal renal function have no increased risk of MI compared with controls, whereas women have at least twice the risk of controls.
Keywords: Acute Coronary Syndrome, Blood Glucose, Blood Pressure, Body Mass Index, Coronary Artery Disease, Diabetes Mellitus, Type 1, Hemoglobin A, Glycosylated, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Myocardial Infarction, Primary Prevention, Renal Insufficiency, Risk Assessment
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