A comparison of the effects of IGF-I and insulin on glucose metabolism, fat metabolism and the cardiovascular system in normal human volunteers

Abstract. The metabolic and cardiovascular effects of recombinant human IGF-I were compared to insulin in six normal subjects. Subjects were studied twice and intravenously received an infusion of [6,6-²H₂]glucose (0–480 min) and in random order either IGF-I 20μg kg^-1 h^-1 (43.7 pmol kg^-1 min^-1) or insulin 0.5 mU kg^-1 min^-1 (3.4 pmol kg^-1 min^-1) with an euglycaemic clamp. One subject was withdrawn following a serious adverse event. During the IGF-I infusion glucose appearance rate (Ra) decreased from 1.79 ± 0.13 at baseline (150–180 min) to 0.35 ± 0.26 mg kg^-1 min^-1 ( P < 0.01) at 360min, and glucose utilization rate (Rd) increased from 1.79 ± 0.28 to 4.17 ± 0.84 mg kg^-1 min^-1 ( P < 0.01). There was no change in free fatty acids (FFA) and an increase (percentage change from pre-infusion mean) in cardiac output + 37.3%± 9% ( P < 0.01), heart rate + 13%± 2% ( P < 0.01) and stroke volume + 21%± 7% ( P < 0.05). During the insulin infusion glucose Ra decreased from 1.89 ± 0.13 to 0.34 ± 0.33 mg kg^-1 min^-1 ( P < 0.01) and FFA from 0.546 mmoll^-1 to 0.198 mmoll^-1 ( P < 0.01), glucose Rd increased from l.89 ± 0.18 to 5.41 ± l.47mg kg^-1 min^-1 ( P < 0.01) and there were no significant changes in the cardiovascular variables.