Quantitative kinetics of glucose appearance and disposal following a13C-labelled starch-rich meal: comparison of male and female subjects

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Abstract
In the UK, starch contributes up to 25 % of energy intake in adults (). The present study investigated the acute response to a starchy meal on whole-body glucose metabolism and assessed insulin sensitivity in men compared with women. Low insulin sensitivity has been postulated to pre-dispose individuals to a cluster of associated abnormalities known to increase the risk of CHD. Metabolic responses to a 13C-labelled meal were determined in conjunction with a primed continuous infusion of D-[6,6-2H]glucose in groups of healthy age- and BMI-matched men and women. Peripheral plasma glucose disposal (Gd) was computed using non-steady state kinetics in a single compartment model, simultaneously with determination of whole-body net glucose oxidation by indirect calorimetry. Insulin sensitivity was derived using cumulative Gd as the dependent variable, and time and the integrated insulin concentration as independent variables. The female group had the higher fractional rate of glucose appearance in plasma from starch (P=0·019) immediately after ingestion. Females also had a higher rate of plasma Gd and a significantly higher insulin-dependent Gd (6·8 v. 5·6 μg glucose/(min.kg) per pmol insulin, P<0·05) compared with the males. A smaller absolute pool of endogenous glucose in females allowed the rate of exogenous 13CO2 production to be significantly higher in the females (P=0·007) corresponding also to a significantly higher (P<0·05) carbohydrate oxidation rate obtained by indirect calorimetry. The present study suggests that during the ingestion of a starchy meal, females exhibit higher glucose flux and greater whole-body insulin sensitivity than males.