Previous studies have demonstrated impaired perinatal adaptation of glucose homeostasis with inappropriately low levels of catecholamines and glucagon in newborn infants born to diabetic mothers. To investigate whether these neonatal changes are related to maternal metabolic control, we sequentially measured plasma glucose, catecholamines and glucagon in the neonatal period in 10 infants born to well-controlled mothers with class B diabetes mellitus after uncomplicated pregnancies. Good glycemic control in the mothers resulted in appropriate counterregulatory hormone responses in the neonatal period, similar to those described in infants born to normal mothers. The significant rise in plasma epinephrine and glucagon paralleled the establishment of euglycemia, further suggesting that these hormones are important for perinatal adaptation of glucose homeostasis.