INTERACTION OF HYPERTENSION AND DIABETES ON RENAL-FUNCTION IN BLACK NIDDM SUBJECTS

We studied renal function of 194 black subjects with duration of diagn osed NIDDM from 1 month to 36 years to determine the interaction of hy pertension and diabetes on nephropathy. Renal function was assessed by isotopic GFR and RPF studies, and serum creatinine. One hundred seven teen of the 194 subjects had 24-hour urinary albumin excretion (AER). AER > 300 mg/24 h correlated with longer duration of NIDDM, decrease i n GFR and RPF, and rise in serum Cr, and all subjects were hypertensiv e. AER 30 to 300 mg/24 h also correlated with a longer duration of NID DM and 80% had hypertension. When 194 subjects were grouped according to duration of NIDDM and the presence or absence of hypertension, subj ects who remained normotensive had normal renal function. In hypertens ive subjects a decrease in GFR occurred with duration of NIDDM > 1 yea r and decrease in RPF with duration of NIDDM > 5 years. In hypertensiv e subjects with NIDDM > 10 years, 36% had impaired renal. function (GF R < 80 ml/min/1.73 m(2) or serum creatinine > 1.4 mg/dl) and 75% had m icroalbuminuria or clinical proteinuria. Within this group, those subj ects who developed hypertension after their diagnosis of diabetes were likely to have evidence of nephropathy as compared to those subjects whose hypertension was diagnosed prior to or simultaneous with their d iabetes: 17 of 20 (85%) versus 7 of 13 (54%), respectively (P = 0.05). These data provide insight into the relationship between hypertension and diabetes in the development of nephropathy in black NIDDM individ uals.