Smoking and metabolic control in patients with insulin-dependent diabetes mellitus

Within a defined geographical area, all 192 subjects with insulin-dependent diabetes of at least 2 years duration and free of diabetic complications were identified; 60 (31%) were smokers. The prevalence of smoking increased significantly with increasing haemoglobin A1c levels (17.5% among subjects with the best metabolic control, 47.5% in those with the worst control). Smoking and non-smoking diabetic patients did not differ in attitudes towards the disease, psychological well-being, extent of tedium, frequency of self-controls of blood glucose or proportion of patients with any sick leave in the preceding 2 years. In a case referent study of 25 matched patients with good or poor metabolic control, exposure to smoking was significantly more common among those with poor control (odds ratio 6.0). Thus there are several lines of evidence that smoking is associated with impaired metabolic control in patients with diabetes.