EFFECTS OF SMOKING ON BLOOD-PRESSURE AND PROTEINURIA IN PATIENTS WITHDIABETIC NEPHROPATHY

Objectives. To investigate the effects of smoking on blood pressure an d proteinuria in hypertensive diabetic patients with nephropathy. Desi gn. Controlled, randomized, cross-over study. Setting. Tertiary care c entre, University Hospital of Dusseldorf, Germany. Subjects. A total o f 25 subjects were recruited, each of whom smoked at least 20 cigarett es a day: 10 normotensive healthy volunteers and 15 hypertensive type 1 (insulin-dependent) diabetic outpatients with diabetic retinopathy a nd persistent micro- or macroalbuminuria; 10 diabetic patients had nor mal autonomic function test, whilst five patients showed signs of auto nomic neuropathy. Interventions. Controlled smoking or nonsmoking over a period of 8 h on separate days. Main outcome measures. Blood pressu re was measured every 10 min with an automatic device and urine sample s were collected every 3 h. Results. Systolic blood pressure increased during smoking in controls (mean) (11.5 mmHg, P = 0.0001) and in diab etic patients without autonomic neuropathy (7.9 mmHg; P = 0.018), but not in patients with autonomic neuropathy (-2.4 mmHg; P = 0.792). Dias tolic blood pressure increased during smoking in controls (6.2 mmHg; P = 0.019) but not in diabetic patients (2.5 mmHg; P = 0.204. 0.2 mmHg; P = 0.956). During smoking, median proteinuria and albuminuria increa sed in diabetic patients without autonomic neuropathy (8.1 mg mmol(-1) creatinine, P = 0.002; and 2.6 mg mmol creatinine, P = 0.084). No sig nificant changes in albuminuria or proteinuria occurred in the other t wo groups. Conclusions. Smoking increases blood pressure values in hea lthy subjects and in hypertensive patients with diabetic nephropathy a nd without autonomic neuropathy. This effect of smoking may be partly responsible for the faster progression of diabetic nephropathy in smok ing diabetic patients.