Growth hormone response to GHRH + GHRP-6 in type 2 diabetes during euglycemic and hyperglycemic clamp.
ABSTRACT The aim of this study was to investigate the effect of two different glucose levels on GH response to the combined administration of GHRH+GHRP-6 in patients with type 2 diabetes. GH response to i.v. bolus of GHRH+GHRP-6 (100 mcg, each) was measured in 12 male patients with type 2 diabetes (mean age: 53.9+/-1.59 years; BMI: 25.58+/-0.39 kg/m(2); mean HbA(1c): 8.7+/-0.42%), during a euglycemic (mean glucose: 4.92+/-0.08 mmol) hyperinsulinemic clamp (insulin infusion rate of 100 mU/kg/h) and a hyperglycemic clamp (mean glucose: 12.19+/-0.11 mmol/l). There was no difference in basal GH levels between the hyperglycemic and euglycemic clamps (2.9+/-0.99 mU/l versus 1.48+/-0.44 mU/l; P>0.05). Peak GH response to GHRH+GHRP-6 during the hyperglycemic clamp was lower than in the englycemic clamp (112.45+/-14.45 mU/l versus 151.06+/-16.87 mU/l; P<0.05). Area under the GH curve was lower in the hyperglycemic than in the euglycemic clamp (6974.49+/-1001.95 mU/l/min versus 9560.75+/-1140.65 mU/l/min; P<0.05). It is concluded that hyperglycemia significantly reduces GH response to combined administration of GHRH+GHRP-6 in normal weight patients with type 2 diabetes. It is suggested that ambient glucose levels should be taken into account during interpretation of GH response to combined administration of GHRH+GHRP-6 in patients with type 2 diabetes.