Studies have been carried out on activities of lysosomal β-N-acetylhexosaminidase (hex), β-galactosidase (β-gal), α-glucosidase (α-glu), and acid phosphatase (AP) in serum and urine from patients with juvenile diabetes and matched controls. There is a large increase in blood and urinary hex activity (the former presenting three distinct patterns of abnormality), a moderate increase in urinary β-gal, and a small increase in urinary α-glu activity, but no elevation of blood or urinary AP in the diabetics. Urinary α-glu activity in the diabetics shows striking inhibition by glucose, and this may reflect a similar phenomenon in vivo.
Although glycohydrolase activities are elevated in patients with no detectable microangiopathy, more striking changes may be observed in patients with severe small-vessel disease. These alterations may be associated with increased glycoprotein catabolism in the diabetic, an area in need of further studies in the human and experimental diabetic animal.