A follow-up study of plasma beta-N-acetylglucosaminidase activity and diabetic retinopathy--observed for 2 years.

The correlation of Plasma beta-N-acetylglucosaminidase (NAG) activity and the development of diabetic retinopathy was observed in 117 diabetic patients (male 52, female 65) who had been observed for 2 years. The plasma NAG activity was measured at least 3 times per year (6 approximately 9 times altogether). The eye-ground findings at the beginning of the study and 2 years later were studied according to Scott's classification. Forty-four percent (19 cases) of the 43 patients with higher NAG activity (greater than 525 nmole/h/ml) and 27% (20 cases) of the 74 patients with lower NAG activity (less than or equal to 525 mole/h/ml) showed a worsening of the eye findings (p greater than 0.05). The frequencies of patients showing a worsening of the eye findings in patients with higher fasting blood glucose (FBG) values (greater than or equal to 140 mg/dl) and in patients with lower FBG values (less than 140 mg/dl) were 45% (17 in 38 cases) and 28% (22 in 79 cases), respectively (p greater than 0.1). When the NAG activity and the FBG value were considered together, there were 16 patients with both higher FBG values or higher NAG activity, and 52 patients with both lower FBG values and lower NAG activity. The frequencies of the patients who had a worsening of the eye findings were 56% (9 cases), 37% (18 cases), and 23% (12 cases), respectively. The difference was significant (p less than 0.05). In the present study, the plasma NAG activity showed no relation to diabetic retinopathy, but the results suggest that the plasma enzyme estimation may add further information to the FBG value and so help in predicting the development of diabetic retinopathy.