To investigate the association between cigarette smoking and the progression of diabetic nephropathy.
A prospective, follow-up study over one year was conducted in a sequential sample of 34 smokers, 35 nonsmokers, and 24 ex-smokers with type I diabetes, hypertension, and diabetic nephropathy. Progression of renal disease was defined according to the stage of nephropathy as an increase in proteinuria or serum creatinine or a decrease in the glomerular filtration rate.
Progression of nephropathy was less common in nonsmokers (11%) than in smokers (53%) and patients who had quit smoking (33%), P > 0.001. In a stepwise logistic regression analysis, cigarette pack years, 24-h sodium excretion, and GHb were independent predictive factors for the progression of diabetic nephropathy. Because blood pressure (BP) was well controlled in these patients and most values were within a normotensive range, neither standing, sitting, nor supine BP values were associated with progression of nephropathy.
Cigarette smoking represents an important factor associated with progression of nephropathy in treated hypertensive type I diabetic patients.