Aims: To investigate the relation of cigarette smoking, alcohol use, and coffee and green tea consumption to glycated hemoglobin (HbA1c) concentrations. Methods: Study subjects were 11,002 Japanese men and women aged 49-76 years in Fukuoka City who participated in the baseline survey of a cohort study on lifestyle-related diseases. Those with current or past treatment for diabetes mellitus were excluded. Multivariate-adjusted geometric means of HbA1c and odds ratios of elevated HbA1c (>
5.8%) were obtained by analysis of covariance and logistic regression analysis, respectively. Results: Cigarette smoking showed a strong, positive association with HbA1c in men, but not in women. In men, adjusted odds ratio of elevated HbA1c was 1.83 (95% CI 1.25-2.69) for those smoking 20 cigarettes/day or more versus never-smokers. HbA1c concentrations were progressively lower with increasing levels of alcohol intake in both men and women. The adjusted odds ratios of elevated HbA1c for the highest alcohol consumption versus never consumption were 0.62 (95% CI 0.43-0.93) in men and 0.94 (95% CI 0.58-1.52) in women. Coffee consumption showed a suggestive inverse association with HbA1c concentrations in women only, while green tea was not related to HbA1c in either men or women. Conclusions: The present findings add to evidence that cigarette smoking confers deterioration in glucose metabolism and that alcohol intake is protective to glucose intolerance. Further studies are needed on coffee and HbA1c concentrations. © 2009 Diabetes India. Published by Elsevier Ltd. All rights reserved.