Combined Effect of Growth Hormone and Cortisol on Late Posthypoglycemic Insulin Resistance in Humans

The occurrence and mechanisms for late (6.5- to 7.5-h) posthypoglycemic insulin resistance were studied with the euglycemic clamp in 19 healthy subjects. Comparisons were made with a control study with the same insulin infusion rate but where hypoglycemia was prevented by glucose infusion. Glucose production and utilization were studied with D-[3-³H] glucose infusions. Hypoglycemia induced marked insulin resistance shown by lower glucose infusion rates compared with the control study 3.1 ± 0.3 vs. 6.0 ± 0.7 mg · kg⁻¹ · min⁻¹ P < .001). This late posthypoglycemic insulin resistance was mainly due to a decreased insulin effect on glucose utilization. Infusion of propranolol did not prevent insulin resistance, whereas somatostatin partially prevented its appearance. Somatostatin plus metyrapone completely normalized posthypoglycemic insulin resistance. A positive correlation (r = .72, P < .001) was found between initial insulin sensitivity and percent reduction of the insulin effect after hypoglycemia. Thus, hypoglycemia is followed by prolonged (6- to 8-h) insulin resistance. In contrast to early-phase (2- to 3-h) resistance, long-term resistance is not due to β-adrenergic stimulation but to the combined effect of growth hormone and cortisol. This resistance is also more pronounced in subjects with initially high insulin sensitivity.