Counter-Regulatory Impairment and the Effect of Microvascular Insulin Transfer in Type 1 Diabetes Mellitus

At 21:30h, an overnight insulin infusion was titrated to control the subjects' BG overnight between 100 and 150mg/dL by blood sampling for plasma glucose via a YSI analyzer every 30min and adjusting the rate of insulin infusion as needed. At the beginning of the clamp, the overnight insulin was replaced by an insulin infusion via a Harvard pump given as a 20mU/kg priming over a 10-min period, followed by a constant rate delivery of 1mU/kg/min until the end of the clamp. Blood was sampled for plasma glucose, and glucose was clamped at basal levels for the euglycemic control period of 150min via a variable-rate infusion of 20% dextrose. Then the glucose concentration was lowered at a rate of 1mg/dL/min to a minimum of 50mg/dL, where it was held constant for 30min. Finally, the glucose concentration was increased at a rate of 1mg/dL/min to 90mg/dL, where it was held for an additional 30min. Blood was sampled for epinephrine during euglycemia, hypoglycemia, and recovery.