Correlates of biopsy-studied nephropathy in young patients with insulin-dependent diabetes mellitus.

We have correlated pathologic findings in kidney biopsies from 12 adolescents with proteinuria or hypertension with severity of limited joint mobility (LJM) and retinopathy. We compared mean glucosylated hemoglobin (GHB) and clinical findings in these patients with those in patients without proteinuria or hypertension. Severity of LJM correlated with basement membrane thickening. Protein excretion correlated with degree of mesangial matrix increase and basement membrane changes. Retinal changes were related to basement membrane thickness and duplication. Despite treatment, blood pressures were significantly higher in patients with nephropathy than in the comparison group. Glycemic control status was generally poor and did not correlate with pathologic changes. The narrow spectrum of control did not permit assessment of possible effects of milder metabolic derangement. However, the similarity of GHB values in the groups with and without nephropathy implicates other factors. The group with clinical nephropathy had more LJM than did the comparison group, reaffirming LJM as a risk factor for early microvascular disease. Biopsy changes of nephropathy may begin relatively early in the course of diabetes (less than 7 years in three of our patients) and is already advanced when proteinuria appears.