Comparison of n-acetyl-β-d-glucosaminidase and alanine aminopeptidase activities for evaluation of microangiopathy in diabetes mellitus

Abstract The activities of urinary n -acetyl-β- d -glucosaminidase (NAG) and alanine aminopeptidase (AAP) were measured in 207 diabetic patients and 57 healthy controls, and the relationship of these enzymes to different stages of diabetic microangiopathy was studied. Diabetics with clinical proteinuria had higher urinary NAG and AAP (17.7 ± 1.9 and 42.8 ± 4.9 U/g creatinine, mean ± SE, respectively) than healthy controls (1.8 ± 0.1 and 10.0 ± 0.4) or diabetics without proteinuria. Among diabetics without proteinuria, NAG excretion in those with retinopathy was slightly higher than in those without (6.4 ± 0.5 v 5.4 ± 0.4), and AAP in those with retinopathy was significantly higher than in those without (23.0 ± 1.5 v 17.4 ± 0.8, P P P 1c than in patients with long duration. Although urinary NAG correlated moderately with AAP ( r = .70, P r = .47 and P v r = .32 and P