Effect of training on response to a glucose load adjusted for daily carbohydrate intake

From responses to identical absolute glucose loads in trained (T) and untrained (UT) subjects, it has been inferred that training promotes health by reducing glucose levels and insulin secretion. To mimic daily living conditions, we studied responses to oral glucose loads making up identical fractions of daily carbohydrate intake (i.e., same relative glucose load) in seven T and eight UT males [maximal O2 uptake (VO2max) 76 +/- 2 vs. 48 +/- 1 (SE) ml.min-1.kg-1; age 24 +/- 1 vs. 25 +/- 1 yr]. Daily energy intake was higher in T than in UT subjects (18,607 +/- 835 vs. 12,493 +/- 720 kJ/day, P less than 0.05), reflecting a 2.3 times higher carbohydrate intake (678 +/- 34 vs. 294 +/- 18 g/day, P less than 0.05). After 1 g/kg body wt glucose, C-peptide and insulin responses were lower in T than in UT subjects (P less than 0.05). However, after identical relative glucose loads [high: 2.3 +/- 0.2 (T) vs. 1 (UT) g/kg; low: 1 (T) vs. 0.4 +/- 0.03 (UT) g/kg], glucose [incremental areas 300 +/- 56 (T) vs. 304 +/- 35 (UT) mM.180 min and 148 +/- 30 (T) vs. 124 +/- 22 (UT)] and C-peptide [181 +/- 18 (T) vs. 171 +/- 27 (UT) nM.180 min, and 100 +/- 13 (T) vs. 71 +/- 12 (UT)] responses did not differ between groups, while insulin responses were lower in T [at low relative load 15 +/- 4 (T) vs. 20 +/- 2 (UT) nM.180 min, P less than 0.05].(ABSTRACT TRUNCATED AT 250 WORDS)