Paradoxical Associations of Diabetes and Obesity with Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA), defined as a localized dilatation of abdominal aorta, is a significant cause of morbidity and mortality in aging populations. AAA is a life-threatening disease mainly because of the high fatality rates associated with aneurysm rupture. Early detection of AAAs will provide patients an opportunity to receive medical therapy and undergo elective repair before aneurysm rupture. Historically, AAA is considered a macrovascular atherosclerotic disease. Classic risk factors of atherosclerosis, such as advanced age, male gender, smoking, hyperlipidemia, and hypertension, have been associated with an increased risk of AAA formation and expansion. However, more recent laboratory and epidemiologic studies have challenged this conventional theory and indicate that the etiology of AAA is distinct from atherosclerosis per se. This review focused on the evidence on the seemingly paradoxical inverse and positive associations of diabetes and obesity, respectively, with AAA. AAA progresses more slowly in diabetics and diabetic patients are less likely to have a ruptured AAA at the time of repair, suggesting that diabetes or its medications may protect against the development and improve the prognosis of AAA. Meanwhile, obesity has been implicated in the pathogenesis of both diabetes and atherosclerosis, for which the key mechanisms include insulin resistance and release of adipokines. Data on the associations between measures of obesity and AAA are inconsistent. Insights into the relation between diabetes, obesity and AAA will help identify high-risk subpopulations for AAA screening and optimize prevention strategy for individual patients. An improved knowledge of the mechanisms underlying the link between diabetes, obesity and AAA also has important therapeutic implications. [N A J Med Sci. 2017;10(2):83-87. DOI: 10.7156/najms.2017.1002083]