Urinary N-acetyl-β-D-glucosaminidase (NAG) was measured in 108 diabetic patients with or without clinical diabetic nephropathy, and the correlation between urinary NAG activity and proteinuria, serum creatinine, and HbAI level were studied.
The results obtained were as follows.
1) The urinary NAG activity levels of non-diabetic controls, diabetics without proteinuria, diabetics with intermittent proteinuria and diabetics with persistent proteinuria were 2.74±1.41 (n=48), 7.70±4.62 (n=48), 12.26±6.35 (n=35) and 19.63±13.07 U/g creatinine (n=25), respectively. Such a marked and stepwise increment of urinary NAG activity suggests that the enzyme may represent a useful indicator of early diabetic renal involvement.
2) No correlation was noted between urinary NAG activity and serum creatinine level.
3) A significant positive correlation was observed between urinary NAG activity and HbAI level (r=0.28, n=75, p<0.02). However, further investigations are required to evaluate the relation between the state of metabolic control and the urinary NAG activity, since insulin-dependent poor control patients were more common among diabetics with persistent proteinuria who formed the high urinary NAG activity group.
