title: Increased insulin sensitivity is associated with reduced insulin and glucagon secretion and increased insulin clearance in man.
abstract: Insulin secretion is increased in insulin resistance. In this study, we examined whether high insulin sensitivity results in low insulin secretion. Twelve male master athletes [age 25.6 +/- 4.1 (mean +/- SD) yr] and seven male sedentary students (age 25.0 +/- 2.0 yr) underwent a hyperinsulinemic, euglycemic clamp and a glucose-dependent arginine stimulation test. Athletes had high insulin sensitivity [230 +/- 18 vs. 92 +/- 12 (nmol glucose/kg.min)/(pmol insulin/liter), P < 0.001] and low insulin response to arginine (at fasting glucose 135 +/- 22 vs. 394 +/- 60 pmol/liter, P < 0.001), which resulted in unaltered disposition index (32.8 +/- 3.8 vs. 33.5 +/- 3.3 micro mol glucose/kg.min, NS). Also, the C-peptide response to arginine was reduced (at fasting glucose 0.71 +/- 0.09 vs. 0.89 +/- 0.09 nmol/liter, P = 0.034). However, the C-peptide reduction was not as large as the insulin reduction yielding increased disposition index in athletes when calculated from C-peptide data (184 +/- 9 vs. 76 +/- 11 micro mol glucose/kg.min, P < 0.001). This difference is explained by increased insulin clearance among the athletes during the first 5 min after arginine (81.1% +/- 1.8% vs. 53.6% +/- 4.7%, P < 0.001). Also, the glucagon response to arginine was reduced in the athletes (58.8 +/- 6.7 vs. 90.1 +/- 9.9 ng/liter at fasting glucose, P = 0.009). We conclude that high insulin sensitivity results in low islet hormone secretion and increased insulin clearance.
authors.affiliation: Department of Medicine (B.A.), Lund University, Lund SE-221 84, Sweden. bo.ahren@med.lu.se
authors.forename: Bo
authors.initials: B
authors.lastname: Ahrén
authors.forename: Ola
authors.initials: O
authors.lastname: Thorsson
mesh_terms: D000328:Adult; D002096:C-Peptide / Q000032:analysis; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005934:Glucagon / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate
chemical_list: D002096:C-Peptide; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005934:Glucagon