PLASMA BETA-HEXOSANINIDASE ISOENZYME-A AND ISOENZYME-B EXHIBIT DIFFERENT RELATIONS TO BLOOD-GLUCOSE LEVELS IN A POPULATION OF TYPE-1 DIABETIC-PATIENTS

The activity of lysosomal enzymes, such as beta-hexosaminidase (Hex), is increased in the plasma and serum of diabetic patients. A positive association has been shown between enzyme activity and glycated protei ns, indicating an association with the degree of metabolic control. Se veral isoenzymes of Hex exist. Studies have reported different proport ions of the isoenzymes in plasma from diabetic patients, compared with healthy subjects. In the present study, Hex isoenzymes were examined in 76 Type 1 diabetic patients, of mean age 37.4 years (SD 12.9) compa red with 38 age- and sex-matched healthy control subjects in an attemp t to evaluate the influence of long- and short-term changes in blood g lucose levels on these isoenzymes. The results show that Hex A activit y (p<0.01), but not Hex B activity, was higher in the diabetic patient s. Hex A activity was positively associated with both the actual blood glucose levels (r=0.48, p<0.001) and haemoglobin A(1c) (HbA(1c)) (r=0 .43, p<0.001), while Hex B activity was associated with the level of H bA(1c) only (r= 0.42, p<0.001). Both Hex A and B activities were also positively associated with early signs of diabetic nephropathy (e.g. u rinary excretion of Hex, fractional albumin excretion ratio and urinar y albumin). There was no association between Hex A and B activities an d different degrees of retinopathy. In conclusion, the present study d emonstrates an association between Hex A and B and metabolic parameter s in diabetes as well as with clinical signs of early diabetic nephrop athy, but no association with the degree of retinopathy. Furthermore, Hex A seems to be more influenced than Hex B by short-term changes in blood glucose levels.