INCREASED URINARY N-ACETYL-BETA-GLUCOSAMINIDASE (NAG) EXCRETION IN YOUNG INSULIN-DEPENDENT DIABETIC-PATIENTS

We evaluated urinary N-acetyl-beta-glucosaminidase (NAG) excretion in overnight and in second morning urine in 50 young diabetic patients, a ged 7.4-25 years with a disease duration from 2-19.6 years. In all pat ients we evaluated urinary NAG and creatinine excretion, in both overn ight and second morning urine, glycosuria, fasting blood glucose and H bA(1c) levels, insulin requirement, blood pressure, and the presence o f microangiopathic complications. Urinary NAG excretion was also evalu ated in 69 age- and sex-matched controls. NAG was determined using -cr esolsulfonphtaleinyl-beta-N-acetylglucosaminide as substrate (Boehring er Mannheim, Germany). In the diabetic patients NAG/Cre ratios were si gnificantly higher than in controls both in overnight and second morni ng urine (P < 0.0005, respectively). We observed significantly higher NAG/Cre ratio levels in the second morning than in overnight urine, bo th in controls and in diabetics (P < 0.0005, respectively). Elevated ( above 2 S.D. of the mean) NAG/Cre ratios were found in 17/50 patients (34%) in overnight urine and in 29/50 (58%) in second morning urine. N o correlation was observed between NAG/Cre ratio levels and age, durat ion of disease, pubertal stage, body mass index, fasting blood glucose , glycosuria, insulin requirement and blood pressure. The patients wit h one or more complications did show NAG/Cre ratio levels significantl y higher than those without complications (P < 0.005) in second mornin g urine, but not in overnight urine. Our study has demonstrated an inc reased rate of urinary NAG excretion in young IDDM patients, in partic ular in those with microangiopathic complications.