Urinary findings and renal function in adult Navajo Indians and associations with type 2 diabetes

We screened a sample of adult Navajo Indians for signs of renal disease that might underlie their increasing rates of renal failure. Nondiabetics had modest rates of hypertension, which was more common in males and increased with age. Microscopic hematuria was very common, and only a fraction was associated with progressive nephropathy. Microalbuminuria, mostly undetected by routine dipstick, was present in 14.6% of subjects; overt albuminuria was present in 2%. Increasing albuminuria was related to renal insufficiency, which was more common in males. Hypertension was associated with greater then threefold increases in both albuminuria and renal insufficiency. Cardiovascular disease was uncommon and had no discernible relationship to albuminuria. Most diabetic patients (58.4%) had hypertension, with equal rates for males and females. Fully half of all diabetic patients had unsatisfactory blood pressure levels at screening. Rates and patterns of hematuria were like those of nondiabetics. Microalbuminuria was present in 36.1% and overt albuminuria in 17.9%, four and eight times the rates in matched nondiabetics, respectively; these differences persisted after controlling for blood pressure. Renal insufficiency was associated with progressive albuminuria and was present in 10.6%, with equal rates in males and females. Hypertension, albuminuria, and renal insufficiency, but not hematuria, increased with increasing diabetes duration. Hypertension was associated with a twofold increase in albuminuria, a threefold increase in overt albuminuria, and an eightfold increase in renal insufficiency. Cardiovascular disease had no detectable association with microalbuminuria, but had a strong relationship to overt albuminuria. The high rates of hematuria are not well explained. It probably has nonrenal as well as renal origins, the latter including mesangial proliferative glomerulonephritis. The impressive rates of albuminuria among diabetic patients mark a large reservoir of renal disease and fore-shadow even larger burdens of end-stage renal disease and cardiovascular disease in the near future. Improved detection and treatment of hypertension is needed to slow the progression of renal disease in nondiabetics and diabetics, together with screening and treatment protocols for albuminuric diabetic patients. Prevention of albuminuria probably involves population-based modification of blood pressure and metabolic profiles.