FUNCTIONAL CHANGES IN ANTITHROMBIN III IN INSULIN-DEPENDENT DIABETES MELLITUS

The thrombin neutralizing activity of Antithrombin III (AT) was measured in a group of patients with insulin-dependent diabetes mellitus. All patients evaluated had diabetes of several years duration. Their blood glucose control was unsatisfactory as evidenced by relative concentrations of glycated hemoglobin (HbA_1c) of 9.6-14.0% determined by polyacrylamide gel electrophoresis. The plasma AT-activity was estimated as thrombin neutralizing activity using the chromogenic substrate Th-1.

The group of diabetic patients had a higher AT-activity than a reference group, but normal AT-concentrations by electro-immunoassay. The treatment of the patient samples with neuraminidase caused a greater fall in the AT-activity than did the treatment of normal samples. The patient samples had a slower mobility in crossed affino-immunoelectrophoresis using immobilized helix pomatia lectin in the first dimension and specific antibodies against AT in the second dimension. The mobility of patient AT, also in complex with thrombin, was indistinguishable from normal AT in crossed immunoelectrophoresis in the presence or absence of heparin.

It is concluded that long-term dysregulation of diabetes mellitus may induce functional changes in the plasma antithrombin activity.