Material and Method: This prospective cohort was a three-year follow-up of Thai Diabetes Registry project that registered 9,370 diabetic patients from 10 diabetic clinics in tertiary medical centers in Bangkok and major provinces between April 2003 and February 2006.

Results: The groups of 7,487 (80%), 1,315 (14%), and 568 (6%) patients were classified as non-smokers, ex-smokers, and current smokers. The crude death rate of ex-smokers (Hazard Ratio (HR) 1.52 (95% CI 1.19-1.95)) and current smokers (HR 1.55 (1.10-2.19)) were higher than death rate of non-smokers. After control for covariates, the HR comparing ex-smokers with non-smokers was not different (1.10 (0.81-1.50)), while the HR comparing current smokers with non-smokers remained statistical significant (1.74 (1.17-2.61)).

Conclusion: Smoking increases mortality rate in diabetic patients by about 74%. Quitting smoking decreased mortality rate to the same rate as of diabetic non-smokers.

Keywords: Diabetes, Smoking, Death rate, Cause of death