Smoking habits and prevalence of clinical diabetic microangiopathy in insulin-dependent diabetics

All patients having insulin-dependent diabetes with onset before 30 years of age and a duration of disease of 12–40 years who visited a diabetes centre within one year were registered. 97% (n=668) answered a WHO questionnaire on cigarette smoking. The smoking habits were compared to the frequency of proliferative retinopathy and/or diabetic nephropathy (persistent proteinuria). The prevalence of diabetic nephropathy was significantly higher among heavy smokers (>10 cigarettes a day for more than one year) than among non-heavy smokers, 19.2% versus 12.1% (p<0.02). An increasing frequency of nephropathy was found with increasing cigarette consumption (p<0.01). No difference in the prevalence of proliferative retinopathy was found between smokers and non-smokers. It is concluded that cigarette smoking is a risk factor for the development of nephropathy in insulin-dependent diabetics.