Paradoxical release of growth hormone during oral glucose tolerance test in patients with abnormal glucose tolerance

Oral glucose tolerance tests were performed on 24 patients characterized as having abnormal glucose tolerance (AGT) and on 27 control subjects. Serums for glucose, growth hormone and insulin determinations were serially obtained for 4 hr after glucose administration. As serum glucose declined 2 hr or more after glucose ingestion a rise in growth hormone, as has been previously described, was observed in 40% of control subjects and 12% of AGT patients. However, of interest was a paradoxical early increase in growth hormone levels noted in 44% of lean AGT subjects occurring during the first 2 hr of the test with glucose levels rising. This response was seen in only one of 8 obese patients with AGT and in none of the control subjects. An abnormality in the hypothalamic glucose receptors in the ventromedial nucleus is a possible explanation for the changes observed. It is possible that this early inappropriate increase in growth hormone release may in some nonobese subjects with AGT contribute to the abnormal oral glucose tolerance tests observed.