A term large-for-gestational age newborn infant was born 50 hours ago by cesarean section to a 26-year-old primigravida mother with insulin-dependent gestational diabetes. The infant's initial glucose was 25 mg/dL, but after feeding subsequent glucoses have all been above 60 mg/dL. The infant is now diaphoretic and irritable, and seems to have some twitching and tremors of the extremities. The most likely cause of this infant's problems is which of the following?