Abstract P440: Diabetes and the Long-term Risk of Abdominal Aortic Aneurysm: The Atherosclerosis Risk in Communities Study

Abstract

Introduction: Diabetes mellitus is known to be related to lower risk of abdominal aortic aneurysm (AAA). However, the full spectrum of glycemic status including prediabetes and the duration of diabetes have not been extensively investigated in the context of AAA risk. Methods: We prospectively studied incident AAA (defined using outpatient records, hospitalization discharge, or death certificate) according to the baseline glycemic status defined using physician diagnosed diabetes, self-reported anti-diabetic medication use and glucose or hemoglobin A1c (diabetes, pre-diabetes, vs. normal glycemia) in 13,116 participants (1990-1992) and the time-varying exposure of duration of incident diabetes in 11,675 participants (1987-1989) using Cox models. We cross-sectionally explored ultrasound-based abdominal aortic diameter by glycemic status and cumulative duration of diabetes in 4,710 participants (2011-2013) using linear regression models. Results: There were 489 incident AAA cases during a median follow-up of ~20 years. Diabetes but not pre-diabetes (vs. normal glycemia) at baseline was independently associated with lower risk of AAA (HR: 0.71 [95%CI 0.51 - 0.99]). The association was largely driven by long-standing diabetes (≥10 years duration: HR: 0.58 [95%CI 0.38 - 0.87]). Longer duration of diabetes was associated with lower risk of AAA (Figure 1A), with 30-50% lower risk in 8 years after incident diabetes diagnosis, as well as smaller aortic diameter measured cross-sectionally (Figure 1B) compared to non-diabetes. Pre-diabetes consistently showed relatively greater diameter (e.g., +0.26 mm [-0.03, +0.54]). Conclusions: Diabetes (but not prediabetes) and its longer duration were independently associated with lower risk of AAA and smaller aortic diameter. Our findings suggest that the cumulative effects of hyperglycemia may play a role in the counterintuitively lower AAA risk. Reduced aortic diameter might be a structural mechanism of decreased AAA risk in diabetes. Figure 1A. Adjusted hazard ratio of incident AAA according to the duration of diabetes among incident cases as a time-varying exposure; Figure 1B. Adjusted difference in maximum diameter (mm) for diabetes vs. non-diabetes by cumulative duration of diabetes. Both models adjusted for age, sex, race, education, BMI, height, total cholesterol, HDL cholesterol, systolic blood pressure, diastolic blood pressure, anti-hypertensive medication, cholesterol-lowering medication, cigarette smoking pack-years, alcohol drinking, eGFR, prevalent peripheral artery disease, prevalent coronary heart disease, and prevalent stroke (time-varying covariates for Figure 1A and baseline covariates for Figure 1B).