Effect of l-dopa on growth hormone, glucose, insulin, and cortisol response in obese subjects

Plasma growth hormone, glucose, insulin and cortisol response to oral administration of L-dopa and in insulin-tolerance test were investigated in 18 obese subjects. The results were compared with the results obtained in 10 normal subjects. The obese subjects displayed a lack of growth hormone responsiveness to L-dopa and a diminished GH responsiveness to hypoglycemia. There was no significant difference in glucose response to hypoglycemia in normal and obese subjects. Obese subjects showed normal increments of plasma cortisol following induction of hypoglycemia although there was no consistent cortisol response after L-dopa administration. A blood glucose response following L-dopa administration was seen in most of normal subjects while no increment of blood glucose was noticed in obese subjects.