N-acetyl-beta-glucosaminidase isoenzymes in serum and urine of patients with diabetes mellitus.

The isoenzyme pattern of N-acetyl-beta-glucosaminidase (NAG) in serum and urine was studied in two groups of patients with diabetes mellitus and in 30 control subjects. Total NAG activity was significantly (P less than 0.001) increased in the serum and urine of the 20 diabetics with vascular complications, but was insignificantly increased in the 20 diabetics without vascular complications. Ion-exchange chromatography demonstrated the presence of two major isoenzymes of NAG, A and B. The proportion of isoenzyme A activity always exceeded that of isoenzyme B. The proportion of isoenzyme B in serum of diabetics was lower than in controls; the reverse was true for urine of diabetics. The NAG isoenzymes pattern may provide additional diagnostic information regarding diabetic status and complications of diabetes.