Blood glucose levels stimulating hypoglycemic counterregulation are related to chronic diabetes control

Intensive insulin therapy is associated with an increased risk of hypoglycemia. To assess the effects of chronic glycemic control on hypoglycemic counterregulation, 21 type I diabetic patients underwent an intravenous insulin infusion of 40 mU/kg/hr for up to 180 min. Five patients had blood glucose levels which fell below 25 mg/dl or significant neurological symptoms ensured. These patients were considered to have inadequate hypoglycemic counterregulation. Of the 16 patients having successfully completed the test, blood glucose levels stabilized at 40 +/- 2 mg/dl after 109 +/- 8 min of insulin infusion, indicating adequate hypoglycemic counterregulation. The levels at which blood glucose stabilized were compared with previous metabolic control as assessed by hemoglobin Alc. A positive correlation (r = 0.57, p = 0.02) was found between the two parameters. It is concluded that (a) long term metabolic diabetes control may affect hypoglycemic counterregulatory mechanisms and (b) intensive insulin therapy may make diabetic patients more vulnerable to hypoglycemia by lowering the effective blood glucose concentration associated with hypoglycemic counterregulation.