Under semiambulatory conditions, 85 consecutive patients with the diagnosis of Type 2 diabetes of short duration (excluding patients with islet cell antibodies or maturity onset diabetes of the young) were admitted to a self-control training program and were examined in this study. A comprehensive renal assessment was performed, including evaluation of albumin excretion rate (AER), renal hemodynamics, blood pressure (BP) profile, and indicators of genetic risk. AER > or = 30 mg/24 h was found in 13 (15%) of patients; in two of these patients, AER was > or = 300 mg/24 h. By logistic regression, high HbA1, current smoking, and BP parameters were significantly correlated with an increased risk of microalbuminuria (MA). In a multiple linear regression model, accounting for 57% of total variance, HbA1, ERPF, and current smoking were significantly correlated with AER. Median GFR (Cin(inulin clearance) 136 mL/min per 1.73m2; range, 94 to 194) and ERPF (Cpah(para-aminohippuric acid clearance) 733; range, 451 to 1328) were significantly higher in patients than in control subjects (upper 95th percentile, 131 and 706 mL/min per 1.73m2, respectively). In a multiple linear regression model, explaining 27% of total variance, age, AER, gender, and fasting blood glucose were significantly correlated to GFR. According to the criteria of average daytime BP > or = 135/85 mm Hg or 24-h BP > or = 130/80 mm Hg, 60% of patients were hypertensive (HT). Sixty-one percent of all patients (including 50% of the untreated normotensive patients) were "nondippers", i.e., < 15% nighttime decrease of mean arterial pressure. Either HT or nondipping was found in 79% of all patients, so that only 21% had a completely normal blood pressure profile. Ninety-four percent of untreated hypertensive patients had no MA. First-degree relatives of patients with MA compared with patients without MA had more frequent cardiovascular events (69% versus 31%). The risk of MA in diabetic patients with positive family history was amplified by poor glycemic control. MA, but not hypertension, was marginally related to K(m) of Na+/Li+ countertransport. It was concluded that (1) microalbuminuria is found in 15% of patients newly presenting with Type 2 diabetes; (2) a high proportion of patients exhibit hyperfiltration; (3) according to ambulatory BP only, 21% of patients have a completely normal circadian BP profile; (4) a family history of cardiovascular events interacts with glycemic control to increase the risk of MA.