The association between diabetes and abdominal aortic aneurysms in men: results of two Danish screening studies, a systematic review, and a meta-analysis of population-based screening studies

BACKGROUND: A paradoxical protective effect of diabetes on the development and progression of abdominal aortic aneurysms (AAA) has been known for years. This study aimed to investigate whether the protective role of diabetes on AAAs has evolved over the years. METHODS: A cross-sectional study, a systematic review and meta-analysis. This study was based on two large, population-based, randomised screening trials of men aged 65-74; VIVA (2008-2011) and DANCAVAS (2014-2018), including measurement of the abdominal aorta by ultrasound or CT, respectively. Analyses were performed using multiple logistic regressions to estimate the odds ratios (ORs) for AAAs in men with diabetes compared to those not having diabetes. Moreover, a systematic review and meta-analysis of population-based screening studies of AAAs to visualise a potential change of the association between diabetes and AAAs. Studies reporting only on women or Asian populations were excluded. RESULTS: In VIVA, the prevalence of AAA was 3.3%, crude OR for AAA in men with diabetes 1.04 (95% confidence interval, CI, 0.80-1.34), and adjusted OR 0.64 (CI 0.48-0.84). In DANCAVAS, the prevalence of AAA was 4.2%, crude OR 1.44 (CI 1.11-1.87), and adjusted OR 0.78 (CI 0.59-1.04). Twenty-three studies were identified for the meta-analysis (N = 224 766). The overall crude OR was 0.90 (CI 0.77-1.05) before 2000 and 1.16 (CI 1.03-1.30) after 1999. The overall adjusted OR was 0.63 (CI 0.59-0.69) before 2000 and 0.69 (CI 0.57-0.84) after 1999. CONCLUSION: Both the crude and adjusted OR showed a statistically non-significant trend towards an increased risk of AAA by the presence of diabetes. If this represents an actual trend, it could be due to a change in the diabetes population. TRIAL REGISTRATION: DANCAVAS: Current Controlled Trials: ISRCTN12157806. VIVA: ClinicalTrials.gov NCT00662480.