Plasma N-acetyl-beta, D-glucosaminidase activities and glycaemia in diabetes mellitus.

The plasma activity of the lysosomal enzyme N-acetyl-beta, D-glucosaminidase (NAGase) has been shown to correlate with hyperglycaemia; their temporal relationships have been investigated. In 12 insulin-treated male diabetic patients, NAGase showed a slight diurnal variation with a nadir at 07.00 h (F = 9.54, p less than 0.001). The mean plasma glucose and NAGase fluctuated similarly (rs = 0.88, p less than 0.01) but did not correlate within individual patients. Normoglycaemia was induced in eight insulin-treated diabetic patients for 4 days but the mean NAGase did not fall significantly. Glycaemic improvement over 3 months was achieved by dietary therapy in 28 newly-presenting non-insulin-dependent diabetic patients: there were significant falls in mean fasting plasma glucose (mean +/- SD: 12.8 +/- 3.3 to 8.3 +/- 3.1 mmol/l; p less than 0.001), glycosylated haemoglobin levels (12.4 +/- 2.4 to 9.3 +/- 2.3%, p less than 0.001) and a corresponding decrease of NAGase (1.5 +/- 0.5 to 1.2 +/- 0.4 mumol 4-nitrophenyl-N-acetyl-beta-D-glucosamide released.h-1.ml-1; p less than 0.001). The change in NAGase correlated with the changes in plasma glucose and glycosylated haemoglobin levels (r = 0.61, p less than 0.025; r = 0.48, p less than 0.05, respectively). Plasma NAGase activity may be influenced by glycaemia in diabetes.