Glucose turnover and hormonal changes during insulin-induced hypoglycemia in trained humans.
Eight athletes (T), studied the third morning after the last exercise session, and seven sedentary males (C) (maximal O2 consumption 65 +/- 4 vs. 49 +/- 4 (SE) ml X kg-1 X min-1, for T and C men, respectively) had insulin infused until plasma glucose, at an insulin level of 1,600 pmol X l-1, was 1.9 mmol X l-1. Glucose turnover was determined by primed constant rate infusion of 3-[3H]glucose. Basal C-peptide (0.46 +/- 0.04 vs. 0.73 +/- 0.06 pmol X ml-1) and glucagon (4 +/- 0.4 vs. 10 +/- 2 pmol X l-1) were lower (P less than 0.05) and epinephrine higher (0.30 +/- 0.06 vs. 0.09 +/- 0.03 nmol X l-1) in T than in C subjects. During and after insulin infusion production, disappearance and clearance of glucose changed identically in T and C subjects. However, in spite of identical plasma glucose concentrations, epinephrine (7.88 +/- 0.99 vs. 3.97 +/- 0.40 nmol X l-1), growth hormone (97 +/- 17 vs. 64 +/- 6 mU X l-1), and pancreatic polypeptide (361 +/- 84 vs. 180 +/- 29 pmol X l-1) reached higher levels (P less than 0.05) and glucagon (28 +/- 3 vs. 47 +/- 10 pmol X l-1) lower levels in T than in C subjects. Blood pressures changed earlier in athletes during insulin infusion, and early recovery of heart rate, free fatty acid, and glycerol was faster. Responses of norepinephrine, cortisol, C-peptide, and lactate were similar in the two groups. Training radically changes hormonal responses but not glucose kinetics in insulin hypoglycemia.
D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D001794:Blood Pressure; D002395:Catecholamines / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D006339:Heart Rate; D006400:Hematocrit; D006728:Hormones / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007003:Hypoglycemia / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D010187:Pancreatic Hormones / Q000097:blood; D005082:Physical Exertion
D001786:Blood Glucose; D002395:Catecholamines; D005230:Fatty Acids, Nonesterified; D006728:Hormones; D007328:Insulin; D010187:Pancreatic Hormones; D013006:Growth Hormone; D006854:Hydrocortisone