Comparison of Urinary N-acetyl-beta-D-glucosaminidase in Non-diabetic Subjects and Type2 Diabetic Patients

For renal impairment, in clinical diagnostic practice currently the assessment of urinary enzymes is used. One of these enzymes is N-acetyl-beta-D-glucosaminidase (NAG), a widely distributed lysosomal enzyme with a molecular weight of 140000 Da, located predominantly in the renal proximal tubules. NAG activity in the urine increases in patients with various glomerulonephritides, diabetic nephropathy, tubulointerstitial diseases, renal allograft rejection and toxic renal injury. The study population included 30 type 2 diabetes and 30 non-diabetic subjects, and the latter group had normal glucose tolerance test. Urinary NAG, albumin, creatinine, serum glucose and HbA1c% were measured. The urinary NAG and albumin index in non-diabetic subjects were compared with those of the diabetic patients. The differences between the two groups (HbA1c<%7 and HbA1c>%7) were calculated. Significant differences were determined in NAG activity between the diabetic and non-diabetic subjects (p< 0.001). Excreted urinary NAG increased in diabetes patients with poor glycemic control (HbA1c>7%) compared to those with good glycemic control (HbA1c<7%), an increase that was significant (p<0.05). There was an increase in urinary NAG excretion in diabetic patients with abnormal albumin excretion compared to those with normal albumin excretion (p= 0.001). NAG excretion had a positive correlation with blood glucose and HbA1c%. Our results showed that determination of urinary NAG activity could be useful marker of early renal damage in diabetic nephropathy and confirmed the use of NAG enzyme as a routine screening test.