No abstract

Plasma N-acetyl-beta-D-glucosaminidase activities are raised in maturity-onset insulin-dependent diabetic patients. Continuous gradient DEAE-cellulose column chromatography and assay of heat-stable enzyme activity both show that the activities of all isoenzymes are equally increased rather than a previously described increase of specific isoenzymes. Plasma enzyme activities are similarly increased in patients with and without diabetic retinopathy, and correlate with simultaneous plasma glucose concentrations.

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.

1. In a cross-sectional study, 32 insulin-treated diabetic patients had elevated low shear (27.1 vs 22.1 mPa s, P less than 0.05) and high shear blood compared with 10 non-diabetic controls. After correction to 45% packed cell volume, the abnormality had a tendency to be greater in patients with proliferative (mean low shear viscosity, 30.8 mPa s) than background (29.2 mPa s) or nil/minimal retinopathy (27.6 mPa s, 0.05 less than P less than 0.97, permutational trend test). 2. The fibrinogen levels were higher in the diabetic group (P less than 0.05) and correlated with the low shear blood viscosity (rs = 0.38, P less than 0.05). 3. In a prospective study, 74 insulin-treated diabetic patients with background retinopathy were randomized into two groups. Thirty-six patients were on attempted improved therapy (A group); in these the mean glycosylated haemoglobin (Hb A1c) fell within 1 year (11.6 to 10.1%, P less than 0.001). both the corrected low shear blood and plasma viscosity fell similarly (P less than 0.001). The fall was greater than in those patients who were kept on usual therapy (U group) and whose glycosylated haemoglobin did not change significantly (11.7 to 11.4% over the year. 4. The effect of diabetes on blood viscosity may not be a direct pathological factor, as the same increased viscosity would be produced by a mean increase of 1.7% in packed cell volume, compared with a population range of 14% packed cell volume.