Background: The contribution of cigarette smoking to development of impaire
d fasting glucose and type 2 diabetes remains unclear.
Objective: To investigate the association of cigarette smoking with develop
ment of impaired fasting glucose and type 2 diabetes.
Design: Prospective cohort study.
Setting: Work site in Osaka, Japan.
Participants: 1266 Japanese male office workers 35 to 59 years of age who d
id 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 d
efined as a fasting glucose level of at least 6.1 mmol/L (110 mg/dL) but le
ss than 7.0 mmol/L (126 mg/dL). Type 2 diabetes was defined as a fasting gl
ucose level of 7.0 mmol/L or more or current receipt of hypoglycemic medica
Results: 87 and 54 men developed impaired fasting glucose and type 2 diabet
es during 5817 and 5937 person-years follow-up, respectively After controll
ing for potential predictors of diabetes, the relative risk for impaired fa
sting glucose compared with never-smokers was 1.62 (95% CI, 0.85 to 3.10) f
or ever-smokers, 1.14 (CI, 0.58 to 2.25) for persons who smoked 1 to 20 cig
arettes/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 multivaria
te-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 7.9
4), and 4.09 (CI, 1.62 to 10.29) (P for trend for current smokers only < 0.
001). The number of pack-years of exposure was also positively related to d
evelopment of impaired fasting glucose and type 2 diabetes (P for trend = 0
.039 and 0.002, respectively). The relative risk for impaired fasting gluco
se and type 2 diabetes in current smokers versus never-smokers was stronger
among men with a body mass index less than 24.2 kg/m(2) than among men wit
h a body mass index of 24.2 kg/m(2) or more, although the absolute risk was
greater in more obese men.
Conclusion: The number of cigarettes smoked daily and the number of pack-ye
ars of exposure seem to be associated with development of impaired fasting
glucose and type 2 diabetes in middle-aged Japanese men.