Nephropathy in siblings of African Americans with overt type 2 diabetic nephropathy.

BACKGROUND

The prevalence of abnormal proteinuria and elevated serum creatinine (sCr) concentrations in diabetic sibs of African Americans (AAs) with overt type 2 diabetic nephropathy (DN) or end-stage renal disease (ESRD) is unknown.

METHODS

We measured urine albumin-creatinine (UAC) ratio, sCr, and hemoglobin A1c (HbA1c) in 211 sibs from 66 families (66 unrelated index cases with overt type 2 DN/ESRD, 132 of their diabetic sibs, and 13 of their nondiabetic sibs). Overt DN was defined as a UAC ratio of 1,000 mg/g or greater or ESRD attributed to diabetes. All index cases had at least one diabetic sib screened.

RESULTS

Given similar mean ages and body mass indices, nondiabetic sibs had lower UAC ratios and HbA1c values compared with diabetic sibs and index cases (Wilcoxon's rank-sum test, all P < 0.006). More than 60% of index cases had at least one diabetic sib with a UAC ratio of 30 or greater and 300 mg/g or less. Nearly 35% of index cases had at least one sib with a UAC ratio greater than 300 mg/g. Nearly 24% of index cases had at least one sib with an elevated sCr level (> or =1.4 mg/dL [124 micromol/L] in women, > or =1.6 mg/dL [141 micromol/L] in men).

CONCLUSION

Asymptomatic elevations in urinary albumin excretion and sCr levels are frequently present in diabetic sibs of AA individuals with overt type 2 DN. Diabetic sibs of AA individuals with type 2 DN should be the focus of intensive screening and intervention programs to slow the current epidemic of diabetic ESRD.