Blunting of spontaneous and alanine-stimulated glucagon secretion in newborn infants of diabetic mothers.

Spontaneous and alanine-stimulated glucagon secretion, and its relation to plasma glucose concentration was investigated in two groups of infants during the initial two hours of life. At birth, plasma glucagon and glucose concentrations were not significantly different in healthy term newborn infants (control subjects) and infants born to insulin-dependent diabetic mothers(IDM-l). In control infants during the first hour of life, glucose fell by 43 +/- 16 mg per deciliter (mean +/- S.E.M.) while plasma glucagon rose by 44 +/- 16 pg. per milliliter (p less than 0.05 for both). However, in IDM-I despite a fall in glucose greater than in control infants, plasma glucagon failed to significantly increase. Intravenous alanine, 150 mg. per kilogram, given at one hour of life, elicited significant increments in glucose and glucagon which were positively correlated in control infants. No significant change in glucose or glucagon occurred in the diabetic group. None of the control infants developed symptomatic or biochemical hypoglycemia (plasma glucose less than 20 mg. per deciliter) whereas five of ten IDM-I developed hypoglycemia. These results suggest that spontaneous and alanine-stimulated glucagon secretion is obtunded in IDM and that this may contribute to hypoglycemia in these infants.