title: Physical fitness and insulin sensitivity in human subjects with a low insulin response to glucose.
abstract: 1. We have assessed insulin secretion, insulin sensitivity, exercise capacity and muscle fibre composition in healthy men with a low insulin response to glucose (low insulin responders and endurance-trained subjects) and in healthy men with a normally high insulin response. Low insulin responders have been considered as prediabetic subjects. 2. During glucose infusion, low insulin responders and endurance-trained subjects had acute-phase (0-10 min) insulin responses that were 26% (P < 0.001) and 31% (P < 0.001), and C-peptide responses that were 35% (P < 0.001) and 42% (P < 0.01), respectively of the responses in high insulin responders. Also, the late-phase (10-60 min) insulin and C-peptide responses were lower in low insulin responders and endurance-trained subjects. Endurance-trained subjects, compared with high and low insulin responders, had higher insulin sensitivity (blood glucose concentration during a somatostatin-insulin-glucose infusion test 3.6 +/- 0.4 versus 6.3 +/- 0.6 mmol/l in high insulin responders, P < 0.01, and 5.5 +/- 0.4 mmol/l in low insulin responders, P < 0.01), exercise capacity (4.2 +/- 0.2 versus 3.0 +/- 0.2 W/kg body weight, P < 0.001, and 2.8 +/- 0.1 W/kg body weight, P < 0.001) and a higher percentage of slow-twitch fibres (58.2 +/- 5.2 versus 38.5 +/- 3.5%, P < 0.01 and 40.9 +/- 3.0%, P < 0.001). 3. In conclusion, we demonstrate that low insulin responders exhibited decreased insulin and C-peptide responses to glucose, despite normal insulin sensitivity and exercise capacity.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Endocrinology, Karolinska Institute, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Pigon
authors.forename: J
authors.initials: J
authors.lastname: Karlsson
authors.forename: C G
authors.initials: CG
authors.lastname: Ostenson
mesh_terms: D000328:Adult; D002096:C-Peptide / Q000378:metabolism; D005947:Glucose; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D000078790:Insulin Secretion; D008297:Male; D009132:Muscles / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D013004:Somatostatin
chemical_list: D002096:C-Peptide; D007328:Insulin; D013004:Somatostatin; D005947:Glucose