Prospective study of the enzymatic activities in urine of N-acetyl-beta-D-glucosaminidase, alpha-D-mannosidase, alpha- and beta-D-glucosidases, alpha-L- and beta-D-fucosidases, and beta-D-galactosidase in type I diabetes mellitus with early nephropathy.
Different surveys have been carried out on the plasma activities of different glycosidases in patients with insulin-dependent diabetes mellitus, but research on urinary glycosidases in this disease is scanty and incomplete. To elucidate the behavior of these lysosomal enzymes in the metabolic alterations occurring in the glomerular basal membrane during the initial stages of diabetic nephropathy, we conducted a prospective study to examine the urinary activities of N-acetyl-beta-D-glucosaminidase (NAG), alpha-D-mannosidase, alpha- and beta-D-glucosidase, alpha-L- and beta-D-fucosidase, and beta-D-galactosidase in patients with type I insulin-dependent diabetes mellitus, surveyed over 18 months, whose early diabetic nephropathy was detected by the presence of microalbuminuria. The simultaneous determination of beta 2-microglobulin in urine confirmed the glomerular origin of the albuminuria. No statistically significant correlation was found between the levels of albuminuria and the activities of any of the glycosidases analyzed. In the diabetic patients, a significant decrease was observed in the activities of all the enzymes (p < 0.05), except NAG and alpha-D-mannosidase, although the decrease in the latter was very close to statistical significance (p = 0.028, unilateral; p = 0.057 bilateral). Similarly, in the patients, there was a significant negative correlation (p < 0.05) with the serum levels of fructosamine, except with beta-D-galactosidase, which showed a positive correlation (p < 0.05) with fructosamine and blood HbA1c.(ABSTRACT TRUNCATED AT 250 WORDS)