Cigarette smoking and glycaemia: the EPIC-Norfolk Study. European Prospective Investigation into Cancer.
BACKGROUND
Previous prospective studies have suggested that cigarette smoking may be associated with an increased risk of type 2 diabetes, but the possibility of confounding, particularly by dietary factors has not been fully examined.


METHODS
Cross-sectional analysis of the association between cigarette smoking and HbA(1C), a marker of long-term glucose homeostasis in 2704 men and 3385 women, aged 45--74 years who were recruited to a population-based study of diet and chronic disease.


RESULTS
Twelve per cent of men and 11% of women reported being current smokers. Mean HbA(1C) was lowest in never smokers, intermediate in former smokers and highest in current smokers. There was a dose-response relationship between HbA(1C) levels and number of cigarettes smoked per day and a positive association with total smoking exposure as measured by pack-years. The unadjusted increase in HbA(1C) for 20 pack-years of smoking was 0.12% (95% CI : 0.09--0.16) in men and 0.12% (95% CI : 0.08--0.17) in women. After adjustment for possible confounders including dietary variables, the values were 0.08% (95% CI : 0.04--0.12) and 0.07% (95% CI : 0.02--0.12) for men and women, respectively. Mean HbA(1C) was inversely related to time since quitting smoking in men.


CONCLUSIONS
These results add support to the hypothesis that smoking has long-term effects on glucose homeostasis, an association that cannot be explained by confounding by dietary factors as measured in this study.
Sargeant
L A
LA
Department of Public Health and Primary Care, University of Cambridge, Institute of Public Health, Robinson Way, Cambridge CB2 2SR, UK.
Khaw
K T
KT
Bingham
S
S
Day
N E
NE
Luben
R N
RN
Oakes
S
S
Welch
A
A
Wareham
N J
NJ
D000368:Aged; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D015986:Confounding Factors, Epidemiologic; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000453:epidemiology; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006305:Health Status Indicators; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D011795:Surveys and Questionnaires
D006442:Glycated Hemoglobin