MUSCARINIC CHOLINERGIC ANTAGONISM DOES NOT ENHANCE RECOVERY FROM HYPOGLYCEMIA IN IDDM

OBJECTIVE - Because muscarinic cholinergic agonism in the absence of a n increase in glucagon secretion inhibits hepatic glucose production, we tested the hypothesis that muscarinic cholinergic antagonism enhanc es glucose recovery from hypoglycemia in insulin-dependent diabetes me llitus (IDDM). RESEARCH DESIGN AND METHODS - Eight (initially euglycem ic) patients with IDDM received overnight infusions of insulin and wer e studied on three occasions in random order. Hypoglycemia was induced by low-dose insulin infusion (4.0 pmol . kg(-1) . min(-1)) from 0 thr ough 80 min; observations were continued through 240 min. At 0 and 80 min, intravenous injections of atropine only (1.0 mg), placebo and the n atropine, respectively, or placebo only were administered. RESULTS - Increments in heart rate (P < 0.001) and prevention of the pancreatic polypeptide response to hypoglycemia (P = 0.042) after atropine admin istration documented muscarinic cholinergic antagonism. The absent glu cagon response to hypoglycemia was unaltered, but the epinephrine resp onse was increased (P = 0.010). Nonetheless, rates of glucose producti on and utilization and plasma glucose concentrations were unaltered. C ONCLUSIONS - We conclude that muscarinic cholinergic antagonism does n ot enhance glucose recovery from hypoglycemia in patients with IDDM.