Urinary excretion of N-acetyl-beta-D-glucosaminidase in children with type I diabetes mellitus.

N-acetyl-beta-D-glucosaminidase (NAG), a lysosomal enzyme, has been shown to be increased in the urine of patients with various glomerulonephritides, tubulointerestitial diseases, renal allograft rejection, toxic renal injury, and diabetes mellitus. Although it has been suggested that urinary NAG may reflect blood glucose control, no studies have correlated this with other measures of metabolic control. Thirty-four children from a diabetic summer camp were found to have urinary NAG to creatinine ratios significantly above those of normal controls of similar age (5.22 +/- 1.19 versus 1.51 +/- 0.17 U). Urinary NAG was found to positively correlate with an arbitrary control index (r = 0.82; P less than 0.05) and in seven patients with hemoglobin A1c (r = 0.70; P less than 0.001). In a closely followed group of 40 clinic patients, urinary NAG to creatinine ratio was again found to be significantly increased over normal controls (7.55 +/- 0.70 versus 1.51 +/- 0.17 U; P less than 0.05). Again, urinary NAG was positively correlated with HbA1c (r = 0.62; P less than 0.001) and urinary albumin to creatinine ratio (r = 0.47; P less than 0.01). In neither group was there a correlation with UNAG:UCr and duration of disease. Thus, these data suggest that urinary NAG to creatinine ratio appears to be a reflection of blood sugar control.