The prevalence of incipient tubular dysfunction, but not of glomerular dysfunction, is increased in patients with diabetes onset in childhood

The study investigated the prevalence of incipient renal dysfunction in two cohorts with identical duration of type I diabetes but with childhood or a dult onset of the disease. The pattern of glomerular (albumin, alb) and tub ular (alpha(1)-microglobulin, alpha(1)-m, and N-acetyl-beta-D-glucosaminida se, NAG) urinary protein excretion was studied in 97 patients with diabetes onset before the age of 16 years and in 53 patients with manifestation of the disease after this age. Diabetes duration was comparable in both groups [9.0 years (1.5-40.0) versus 9.0 (1.0-34.0), p = 0.738]. Although there wa s no difference concerning the prevalence of microalbuminuria (albumin excr etion > 30 mu g/g creatinine), patients with diabetes onset in childhood sh owed significantly higher excretion of NAG compared to those with diabetes onset after the age of 16, The excretion of both tubular markers (alpha(1)- m and NAG) correlated significantly with HbA(1c)-values in both groups. In multiple regression analysis, tubular proteinuria (alpha(1)-m) and diabetes duration correlated significantly to microabuminuria (multiple R = 0.60, p < 0.001). These data suggest that there is no difference concerning the pr evalence of incipient diabetic glomerulopathy between patients with an earl y or a late onset of diabetes. However, a more frequent impairment of tubul ar function was found in young patients with diabetes onset in childhood, w hich might be due to a nonoptimal glycemic control in this population. (C) 2000 Elsevier Science Inc.