Abstract P138: Smoking Timing, Genetic Susceptibility, and Risk of Incident Type 2 Diabetes: A Cohort Study in UK Biobank

Objective: Smoking is an establish risk factor for type 2 diabetes (T2D); however, little is known about how the timing patterns of smoking is related to T2D risk. We prospectively assessed the association of smoking timing with risk of T2D and examined whether smoking amount or genetic susceptibility might modify the relationship. Methods: This study analyzed 294815 participants from the UK Biobank who were free of diabetes at baseline and with complete data on the time from waking to the first cigarette. Cox proportional hazards models were used to evaluate the association between smoking timing and risk of incident T2D. Results: During a median follow-up time of 12 years, a total of 9937 incident cases of T2D were documented among the 294815 participants. Compared to non-smokers, shorter time from waking to the first cigarette was significantly associated with a higher risk of incident T2D ( P for trend <0.0001). The adjusted hazard ratio (aHR) associated with smoking timing was 1.46 (95% confidence interval [CI] 1.17-1.81) for >2 hours, 1.51 (1.21-1.87) for 1-2 hours, 1.58 (1.34-1.85) for 30-60 minutes, 1.86 (1.57-2.21) for 5-15 minutes, and 2.01 (1.60-2.54) for <5 minutes, respectively. We found that even among light smokers, those with the shortest time from waking to the first cigarette had a 105% higher risk of T2D (HR 2.05, 95% CI 1.52-2.76), which was comparable to heavy smokers. The genetic risk score for T2D did not modify this association ( P -interaction =0.51). Conclusions: Our findings indicate that shorter time from waking to the first cigarette is significantly associated with a higher risk of incident T2D, independent of the amount of cigarettes smoked.