Impact of diabetes on crash risks of truck-permit holders and commercial drivers

OBJECTIVE -The U.S and some Canadian government agencies have waived commer cial license restrictions for some insulin-using diabetic drivers. However, the U.S. Federal Highway Administration is no longer giving waivers. Scien tific evidence to support such regulations has been sparse. This article pr esents detailed analyses of crash risks for users and nonusers of insulin a mong diabetic truck-permit holders in Quebec, Canada. RESEARCH DESIGN END METHODS - Diabetic truck-permit holders were group-matc hed by age to a random sample of healthy permit holders. Data on permits, m edical conditions, and crashes involving 13,453 permit holder-years in 1987 -1990 were extracted from the files of the public insurer for automobile in juries in Quebec. Additional health status data were obtained from the prov incial public health insurer. A telephone survey was conducted to collect d ata on driving patterns and exposure. Risk ratios were estimated using nega tive binomial regression models. RESULTS - Risk ratios for crashes vary by category of diabetes. Permit hold ers for single-unit trucks (STs) who are diabetic without complications and not using insulin have an increased crash risk of 1.68 when compared with healthy permit holders of the same permit class. When controlling for risk exposure, commercial drivers with an ST permit and the same diabetic condit ion have an increased risk of 1.76. Insulin use is not associated with high er crash risk. CONCLUSIONS - The increased crash risk for the group with uncomplicated dia betes not using insulin is a new finding. The lack of consistent increases in crash risks among diabetic commercial drivers with complications or who use insulin may be a "healthy worker effect" masking the real risk, because these licensees have a lower participation rate as professional drivers.