Risk of insulin-dependent diabetes mellitus in patients undergoing carotid endarterectomy

There is conflicting evidence regarding the association of diabetes mellitus (DM) and insulin use with outcomes after carotid endarterectomy (CEA). Therefore, we sought to evaluate the risk of insulin-dependent DM (IDDM) and noninsulin-dependent DM (NIDDM) on 30-day outcomes after CEA. We identified patients undergoing CEA from the Targeted Vascular module of the National Surgical Quality Improvement Program (2011-2015) and stratified patients on the basis of their preprocedural symptom status. We compared 30-day outcomes between nondiabetics and patients with NIDDM or IDDM, with 30-day stroke/death as the primary end point. Of 16,739 CEA patients, 9784 (58%) were asymptomatic, of whom 6720 (69%) had no diagnosis of DM, 1109 (11%) had IDDM, and 1955 (20%) had NIDDM. Of the 6955 symptomatic patients, 4982 (72%) had no diagnosis of DM, 810 (12%) had IDDM, and 1163 (17%) had NIDDM. Among asymptomatic patients, patients with IDDM experienced higher rates of 30-day stroke/death compared with those without DM (3.4% vs 1.5%; P < .001), whereas those with NIDDM experienced rates similar to those of patients without DM (2.1% vs 1.5%; P = .1). Moreover, asymptomatic patients with IDDM and an anatomic high-risk criterion experienced a 30-day stroke/death rate of 6.6%. After adjustment, IDDM was associated with 30-day stroke/death in asymptomatic patients compared with patients without DM (odds ratio, 2.3; 95% confidence interval, 1.5-3.4; P < .001), but NIDDM was not (odds ratio, 1.4; 95% confidence interval, 1.0-2.1; P = .1). In comparison, among symptomatic patients, those with IDDM and NIDDM experienced similar rates of 30-day stroke/death as patients without DM (4.9% vs 3.6% and 4.0% vs 3.6%; both P > .1). After adjustment, neither IDDM nor NIDDM was associated with 30-day stroke/death in symptomatic patients compared with symptomatic patients without DM. Rates of 30-day stroke/death after CEA in asymptomatic patients with IDDM exceed international vascular societies' guideline thresholds for acceptable outcomes in asymptomatic patients, especially those with anatomic high-risk criteria. Thus, asymptomatic patients with IDDM may not benefit from CEA, although more data are needed about the natural history of carotid disease in this population.