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

Abstract

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.

Changes of isoenzymes of serum N‐acetyl‐β‐D‐glucosaminidase in relation to different types of diabetes

“…IDDM and 2.71 in NIDDM. Consequently, the activity contribution of the B form in the total activity of serum NAG in diabetics decreases, because the activity contribution of the intermediary forms increaseS,The lower values of serum and higher values of urinary NAG of the B form in diabetics with vascular complications compared to normal individuals was also found by Severini et al (14). These changes of isoenzyme forms in diabetes are interesting in view of the fact that there is similarity in structure of the A and I forms (o~ and 13 subunits), and not between the B (only [3 subunits) and I forms.…”

“…Thus Serrano et al (13) established that the content of glucohydrolases in diabetics was increased, but that this increase is independent of microangiopathic changes and of diabetes duration. On the other hand, Severini et al (14) found the activity of NAG significantly increased only in the serum and urine of patients suffering from vascular complications, while in the patients having no complications it was increased but not significantly. Waters et al (15) found no difference of the activity of NAG between diabetics with or without microangiopathy.…”

“…The fact that the activity of the isoenzyme of NAG in diabetes change (14,19,20,21) makes the issue even more complex, but at the same time it opens the possibility to solve the problems by investigating the isoenzymic forms in diabetes. Activities of urinary NAG isoenzyme (both A and B) in diabetic nephropathy (22) were higher than in controls.…”

Urinary N‐acetyl‐β‐D‐glucosaminidase activity predicts development of diabetic nephropathy

“…10,[12][13][14] Further, many studies have shown that urinary NAG activity was associated with diabetic retinopathy and that it was increased in diabetic patients without detectable signs of nephropathy. 10,[15][16][17][18] In UKPDS, 13 the relationships between urinary NAG and urinary albumin excretion were studied in 716 type 2 patients at diagnosis of diabetes and 195 age-matched control subjects. In a multivariate analysis, urinary NAG and albumin excretion correlated with each other, and with fasting plasma glucose, respectively.…”

“…Increased urinary NAG excretion has been reported in both type 1 and type 2 diabetic patients. [10][11][12][13][14] Past cross-sectional studies have shown that urinary NAG activity was associated with microvascular abnormalities in diabetic patients, [15][16][17] and that it was positively correlated to the level of albuminuria. 13,18 These studies suggest that urinary NAG activity may be a valuable predictor for the development of diabetic nephropathy.…”