Smoking and diabetic nephropathy.

Forty-seven patients with insulin-dependent diabetes (IDDM) and diabetic nephropathy and 47 controls with IDDM without diabetic nephropathy were interviewed about their previous and current smoking habits. The patients in the two groups were matched according to sex, age, age at onset, and duration of diabetes. All patients in the nephropathy group had proteinuria and decreased glomerular filtration. None in the control group had ever had proteinuria as tested by dip stick. The total amount of smoking until date of interview was estimated for each individual and presented as an index. The patients with nephropathy had a significantly higher smoking index than the controls. In the nephropathy group there were also more numerous current smokers, more heavy smokers and fewer individuals who had never smoked than in the control group. The link between diabetic renal microangiopathy and smoking may be through mechanisms such as increased platelet aggregation, accentuated tissue hypoxia and hemodynamic or metabolic effects of repeated noradrenaline release.