Background: The contribution of cigarette smoking to development of impaired fasting glucose and type 2 diabetes remains unclear.
Objective: To investigate the association of cigarette smoking with development of impaired fasting glucose and type 2 diabetes.
Design: Prospective cohort study.
Setting: Work site in Osaka, Japan.
Participants: 1,266 Japanese male office workers 35 to 59 years of age who did not have impaired fasting glucose or type 2 diabetes and were not taking medication for hypertension at study entry.
Measurements: Fasting plasma glucose levels were measured at annual health examinations from May 1994 through May 1999. Impaired fasting glucose was defined as a fasting glucose level of at least 6.1 mmol/L (110 mg/dL) but less than 7.0 mmol/L (126 mg/dL). Type 2 diabetes was defined as a fasting glucose level of 7.0 mmol/L or more or current receipt of hypoglycemic medication.
Results: 87 and 54 men developed impaired fasting glucose and type 2 diabetes during 5,817 and 5,937 person-years follow-up, respectively. After controlling for potential predictors of diabetes, the relative risk for impaired fasting glucose compared with never-smokers was 1.62 (95% CI, 0.85 to 3.10) for ever-smokers, 1.14 (CI, 0.58 to 2.25) for persons who smoked 1 to 20 cigarettes/d, 1.33 (CI, 0.63 to 2.80) for those who smoked 21 to 30 cigarettes/d, and 2.56 (CI, 1.32 to 4.95) for those who smoked 31 or more cigarettes/d (P for trend for current smokers only = 0.013). The respective multivariate-adjusted relative risks for type 2 diabetes compared with never-smokers were 1.08 (CI, 0.34 to 3.42), 1.88 (CI, 0.71 to 5.00), 3.02 (CI, 1.15 to 7.94), and 4.09 (CI, 1.62 to 1,029) (P for trend for current smokers only < 0.001). The number of pack-years of exposure was also positively related to development of impaired fasting glucose and type 2 diabetes (P for trend = 0.039 and 0.002, respectively). The relative risk for impaired fasting glucose and type 2 diabetes in current smokers versus never-smokers was stronger among men with a body mass index less than 242 kg/m2 than among men with a body mass index of 24.2 kg/m2 or more, although the absolute risk was greater in more obese men.
Conclusion: The number of cigarettes smoked daily and the number of pack-years of exposure seem to be associated with development of impaired fasting glucose and type 2 diabetes in middle-aged Japanese men.