Risk of motorcycle collisions among patients with type 2 diabetes: a population-based cohort study with age and sex stratifications in Taiwan

Aims To investigate the overall and sex-age-specific absolute and relative risks of motorcycle collisions at road traffic accidents among patients with type 2 diabetes. Methods A cohort study in Taiwan was conducted by following 989,495 patients with type 2 diabetes and the same number of matched controls recruited between 2010 and 2012 to the end of 2016. Collision events by motorcycle driver victims were identified from the Police-reported Traffic Accident Registry. Overall and sex-age-specific incidence rates of collision involving motorcycle driver victims were estimated under Poisson assumption. The Cox proportional hazard regression models were performed to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of collision in association with type 2 diabetes. Results Over an up to 7 years of follow-up, patients with type 2 diabetes had a higher incidence rate of motorcycle collision than controls at 1.16 and 0.89 per 100 person-years, respectively, which represented a significantly elevated HR of 1.28 (95% CI 1.27-1.30) after adjusting for potential confounders including various diabetic complications. The elevated HR was similarly seen in both men and women patients, and was significantly decreasing with increasing age regardless of sex. Little evidence supported the dose-response relationship between duration of type 2 diabetes and motorcycle collision risk. Conclusions After adjustment for common diabetic complications and comorbidities that could impair driving performance, patients with type 2 diabetes still suffered from increased risk of motorcycle collisions, regardless of sex, but was more evident in younger than in older patients.