Incipient and Overt Diabetic Nephropathy in African Americans With NIDDM

Abstract

OBJECTIVE To determine the prevalence of incipient and overt nephropathy in African- American subjects with non-insulin-dependent diabetes mellitus(NIDDM) attending a hospital clinic. Contributory factors, such as blood pressure (BP), duration and age at onset of diabetes, hyperglycemia, hyperlipidemia, and body mass index (BM1) also were evaluated. RESEARCH DESIGN AND METHODS We recruited 116 African-American subjects with NIDDM for this cross-sectional, descriptive, and analytical study. BP, BMI, 24-h urine albumin excretion, creatinine clearance, serum creatinine, lipids, and GHb levels were measured. Albumin excretion rate (AER) was calculated, and subjects were divided into three groups: no nephropathy (AER <20 μg/min), incipient nephropathy (AER 20–200 μg/min), and overt nephropathy (AER >200 μg/min). Frequency of hypertension and nephropathy was analyzed by x2 testing, group means were comparedusing analysis of variance, and linear correlations were performed between AER and other variables. Multiple regression analysis was used to examine theassociation of these variables while controlling for the effects of other variables. RESULTS Increased AER was present in 50% of our subjects; 31% had incipient and 19% had overt nephropathy. Hypertension was present in 72.4%; nephropathy, particularly overt nephropathy, was significantly more prevalent in the hypertensive group. Mean BP and diastolic blood pressure (dBP) were higher in the groups with incipient and overt nephropathy, and systolic blood pressure (sBP) was increased in overt nephropathy. Men with either form of nephropathy had higher sBP, dBP, and mean BP, whereas only women with overt nephropathy had increased sBP and mean BP. Subjects with incipient or overt nephropathy had a longer duration of diabetes, and those with overt nephropathyhad a younger age at onset of diabetes. By multiple regression analysis, AER correlated with younger age at diabetes onset, but not with diabetes duration. No correlation with age, lipid levels, or GHb was noted. BMI correlated with AER. CONCLUSIONS Incipient and overt nephropathy were observed frequently inthese African-American subjects with NIDDM. Albuminuria correlated with BP, younger age at diabetes onset, and BMI. Association of albuminuria and increased cardiovascular mortality may place 50% of inner-city African-American patients with NIDDM at risk for developing cardiovascular complications.