Insulin Dependence Erodes the Cardiac and Survival Advantage of Asymptomatic Status After Carotid Revascularization

Diabetes mellitus (DM) is associated with adverse outcomes after carotid revascularization, with insulin dependence conferring risk beyond DM alone. How this risk varies by symptom status and intervention type remains unclear. We evaluated the independent association of insulin-dependent (IDDM) and non-insulin-dependent DM (NIDDM) with 30-day and 1-year outcomes after carotid endarterectomy (CEA), transcarotid artery revascularization (TCAR), and carotid artery stenting (CAS), stratified by symptom status.

The Vascular Quality Initiative registry was queried for carotid interventions performed January 2005-January 2025. Patients were stratified by insulin-dependence and symptom status at presentation. Endpoints were 30-day and 1-year myocardial infarction (MI), ipsilateral stroke, all-cause mortality, ipsilateral stroke or death, and major adverse cardiovascular events (MACE; MI, ipsilateral stroke, or mortality). Multivariable logistic regression adjusted for demographic, clinical, and procedural covariates estimated odds ratios (ORs).

Of 275,668 patients meeting inclusion criteria, 73,582 (26.7%) had DM: 44,041 (59.9%) NIDDM and 29,541 (40.1%) IDDM. At 30 days there were 1,645 MIs, 2,051 ipsilateral strokes, 1,806 deaths, 3,626 strokes or deaths, and 5,029 MACE; at 1 year, 2,378, 2,924, 8,269, 10,750, and 12,646, respectively. Controlling for comorbidities and procedure type, IDDM was independently associated with elevated odds of 30-day MI (OR 1.63), ipsilateral stroke (OR 1.24), mortality (OR 1.19), and MACE (OR 1.19), but not ipsilateral stroke or death. Excess IDDM risk was concentrated among asymptomatic patients (30-day MACE OR 1.35 vs 1.07 in symptomatic patients; interaction P<0.001). Asymptomatic IDDM patients had higher 30-day MI odds (OR 1.54, P<0.001) than symptomatic patients without DM, with equivalent 30-day MACE (OR 1.05, P=0.41) and higher 1-year MACE (OR 1.19, P<0.001). Relative to CEA, TCAR and CAS were associated with higher 30-day ipsilateral stroke odds (OR 2.10 and 1.93, respectively, P≤0.01 for both) without differences in MI or mortality; an interaction with insulin dependence was nonsignificant for every endpoint.

Insulin-dependent, diabetes was independently associated with substantially elevated odds of MI, ipsilateral stroke, mortality, and MACE after carotid revascularization, with risk sustained at 1 year. For cardiac and survival endpoints, asymptomatic patients with IDDM occupied a risk stratum comparable to symptomatic patients without diabetes. Asymptomatic status may therefore not confer the same composite risk advantage in insulin-dependent patients, with the excess being cardiac- and survival-driven. These findings support more cautious, individualized counseling and shared decision-making for asymptomatic patients with IDDM and identify insulin dependence as a clinically important, currently underemphasized modifier of perioperative risk.