Growth hormone secretion during sleep: Impairment in glucose tolerance and nonsuppressibility by hyperglycemia

Intravenous and oral glucose tolerance tests were done and EEG were monitored on healthy subjects following nights of normal sleep, following nights during which deep sleep and concomitant GH release were delayed until early in the morning, and following nights in which deep sleep and GH elevation were deprived. Glucose tolerance tests were also done at 1: 00 AM while awake and while sleeping, 90 min following the GH-release deep sleep period. Glucose tolerance was unchanged following the night of deep sleep deprivation, during which time no GH peaks were found. However, following deep sleep during which GH release occurred, significant glucose intolerance was seen. Glucose intolerance was demonstrated both in the sleeping subject at 1: 00 AM and in the awake subject on the morning following deep sleep and concomitant GH release delay. Serum immunoreactive insulin concentrations during the glucose tolerance tests following GH release were unchanged as compared to control. Sustained hyperglycemia prior to and during deep sleep failed to suppress GH release.