Clinical Significance of Urinary Enzymes in Diabetes Mellitus

The aim of this study was to clarify the clinical significance of urinary enzyme activity in patients with diabetes mellitus. Patients were divided into two groups: group A - 102 outpatients, group B-23 inpatients. Spot urine samples before breakfast from group A and aliquots of 24-hours urine collections at 4 degrees C from group B were used. Urinary enzyme activities (N-acetyl- beta-D-glucosaminidase: NAG, alkaline phosphatase: ALP, leucine aminopeptidase: LAP, gamma-glutamyl transpeptidase: gamma-GTP) were determined by spectrophotometric assay, rate assay, Tuppy method and Orlowski method, respectively. 1) In group A, the percentage of the cases which showed higher than the normal range (NAG: 1.3-8.7, ALP: 4.2-17.7, LAP: 0-22.9 U/g. cer.) was 42.2% in NAG, 21.6% in ALP, and 8.8% in LAP. In a multiple regression analysis, the predictor variables which contributed to NAG were HbA1c, age, urinary protein and the one that contributed to ALP, LAP, gamma-GTP was urinary beta 2-microglobulin. 2) In group B, 87% of NAG was above the normal range (Mean +/- 2 SD; 4.8 +/- 3.9 U/day). There was no difference in the NAG activity between patients with and without nephropathy. The percent of high activities of ALP, LAP and gamma-GTP were 17%, 17%, 4%, respectively. Most of them were patients with nephropathy. There were correlations among ALP, LAP and gamma-GTP, though no correlation existed between NAG and the other three enzymes. These results suggested: 1) NAG reflects lysosomal dysfunction of both glomerular and proximal tubular epithelial cells which may be caused by poor glycemic control.(ABSTRACT TRUNCATED AT 250 WORDS)