Diabetes is associated with increased myocardial infarction risk regardless of coronary artery disease status: a 15-year follow-up study
A Odgaard, C Gyldenkerne, N Sattar, H T Soerensen, M Maeng, K K W OlesenAbstract
Background
Prior studies with shorter follow-up have suggested that diabetes may not confer additional myocardial infarction (MI) risk in patients without coronary artery disease (CAD) as confirmed by coronary angiography - suggesting that CAD, rather than diabetes alone, drives MI risk in patients with diabetes.
Purpose
To examine whether diabetes independently increases long-term MI risk in patients with and without angiographically confirmed CAD, and to quantify the absolute risk differences between these groups.
Methods
We included 167,774 consecutive patients undergoing coronary angiography in Western Denmark (2003-2021) and followed them for up to 15 years through linkage to Danish administrative and health care registries. Patients were stratified by diabetes and CAD status. MI was the main outcome, analyzed using cause-specific Cox regression adjusted for age, sex, hypertension, smoking, previous stroke, peripheral artery disease, and statin treatment. Fifteen-year cumulative incidence proportions and risk differences were estimated using the Aalen-Johansen estimator accounting for the competing risk of death. Patients with diabetes were compared to patients without diabetes with similar CAD status.
Results
The median follow-up time was 7.7 years (first quartile - third quartile: 4.0-12.0). Patients with diabetes were more frequently treated with statins, anti-hypertensive agents, and anti-thrombotic medication than patients without diabetes. Fifteen-year absolute MI risk was 4.1% (no diabetes, no CAD), 5.8% (diabetes only), 14.5% (CAD only), and 19.4% (diabetes and CAD) (Figure 1). The absolute risk difference attributable to diabetes was markedly smaller in the absence of CAD (1.7%; 95% CI 0.8-2.6) than in its presence (4.9%; 95% CI 3.7-6.1). Despite this, diabetes was independently associated with increased MI risk both in patients without CAD (aHR 1.30; 95% CI 1.13-1.50) and with CAD (aHR 1.40; 95% CI 1.32-1.47).
Conclusions
Contrary to prior shorter-term evidence, diabetes was independently associated with increased MI risk even in patients with angiographically normal coronary arteries. Nevertheless, CAD remains the dominant driver of absolute MI risk, and the incremental absolute risk conferred by diabetes is markedly attenuated in its absence. These findings underscore the importance of dual diabetes and CAD prevention.Figure 1