We examined net pancreatic norepinephrine (NE) spillover, pancreatic polypeptide (PP) release, and the decrement in C-peptide to identify factors involved in the blunted counterregulatory glucagon response in pregnancy. Conscious pregnant (Ph; 3rd trimester; n = 8) and nonpregnant (NPh; n = 6) dogs were studied during insulin-induced (~12-fold basal insulin concentrations) hypoglycemia (plasma glucose 3.1 mM). Additional dogs were studied during hyperinsulinemic euglycemia (NPe, n = 4; Pe, n = 5; plasma glucose 6 mM). Arterial glucagon concentrations declined similarly in NPe and Pe. AUCs of the changes in glucagon and epinephrine were 7- and 3-fold greater in NPh than Ph (P < 0.05 between groups for both). Glucagon secretion fell below basal in NPe, Pe, and Ph but rose significantly in NPh. C-peptide declined 0.25 ± 0.06, 0.12 ± 0.11, 0.28 ± 0.05, and 0.13 ± 0.02 ng/ml in NPe, Pe, NPh, and Ph, respectively (P < 0.05, NPh vs Ph). AUCs of NE spillover were 516 ± 274, 265 ± 303, 506 ± 94, and -63 ± 79 ng, respectively ((P < 0.05, NPh vs Ph). The AUC of PP release was ~3-fold greater in NPh than Ph ((P < 0.05) but not different between euglycemic groups. The current evidence strongly suggests that the blunting of glucagon secretion during insulin-induced hypoglycemia in pregnancy is related to generalized impairment of a number of different signals, including parasympathetic and sympathoadrenal stimuli, and altered sensing of circulating and/or intraislet insulin.