Plasma glycohydrolase levels in patients with type 1 diabetes at onset and in subjects undergoing an intravenous glucose tolerance test

Abstract

The effect of hyperglycemia and insulin deficiency on the plasma level of lysosomal glycohydrolases, namely N-acetyl-β- D-glucosaminidase, β- D-glucuronidase, α- D-galactosidase, and α- D-glucosidase, was investigated. Two patient groups were assessed: (1) 28 children with type 1 diabetes at onset (fasting blood glucose, 444 ± 154 mg/100 mL; hemoglobin A 1c, 11.9% ± 2.4%; symptom duration, 15.9 ± 8 days; and absence of complications), (2) 14 adult subjects undergoing an intravenous glucose tolerance test (IVGTT), consisting of 8 non-obese subjects (body mass index, 26 ± 0.04 kg/m 2; fasting blood glucose, 82 ± 13 mg/100 mL; blood insulin, 6 ± 0.04 mU/L) and 6 obese subjects (fasting blood glucose, 97 ± 3.5 mg/100 mL; blood insulin, 27 ± 6 mU/L, with normal oral glucose tolerance test). Enzyme activity was determined with the fluorimetric method. The mean level of all evaluated enzymes was significantly increased in patients with type 1 diabetes at diagnosis compared with normal controls. Increased enzyme levels were also detected in the group of adults undergoing an IVGTT in whom hyperglycemia was accompanied by insulin resistance (ie, obese subjects). Glycohydrolase abnormalities appear to be related to insulin deficiency rather than hyperglycemia. Lysosomal apparatus abnormalities seem to be an inherent feature of diabetes that is present at disease onset. The possible role of insulin in the regulation of plasma glycohydrolase levels is discussed.