Abnormal growth hormone response in obesity with normal carbohydrate tolerance and normal thyroid function.

Growth hormone (HGH) response to glucose-induced hyperglycemia and insulin-induced hypoglycemia in 13 obese adults without carbohydrate intolerance and with normal thyroid function were compared with 16 normal weight subjects. HGH levels measured 30 min after placing an indwelling needle in an antecubital vein were significantly lower in obese than in the non-obese controls. HGH concentrations were inversely related to the body weight in all subjects. In the obese group a suppression of serum HGH level was lacking during glucose-induced hyperglycemia and furthermore it was recorded that HGH response to insulin was significantly less as compared with controls. These data indicate that abnormal HGH response is a characteristic in obesity with normal carbohydrate tolerance and normal thyroid function. HGH is a potent physiological stimulatory of lipolysis and it is thus tempting to speculate that an impaired HGH secretion leads to a diminished lipolysis and further deposition of excessive fat in obesity.