Quantification of insulin secretion in relation to insulin sensitivity in nondiabetic postmenopausal women.
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To evaluate mechanisms underlying the close association between insulin secretion and insulin sensitivity, insulin sensitivity was evaluated by the euglycemic-hyperinsulinemic clamp technique (M/I(clamp)) and insulin secretion was determined from the 75-g oral glucose tolerance test (OGTT) and from the glucose-dependent arginine-stimulation test in 81 nondiabetic postmenopausal women, all aged 61 years. M/I(clamp) was normally distributed with mean plus minus SD of 69.9 plus minus 30.5 nmol glucose center dot kg(-1) center dot min(-1)/pmol insulin center dot l(-1). It was found that the several different measures of insulin secretion from the OGTT and the glucose-dependent arginine-stimulation test were all inversely related to M/I(clamp). However, measures determining the direct insulin responses were more markedly potentiated by low M/I(clamp) than were measures determining glucose potentiation of insulin secretion. Moreover, the product of M/I(clamp) times measures of insulin secretion (disposition index [DI]) was inversely related to the 2-h glucose value. Finally, surrogate insulin sensitivity measures quantified from OGTT and the glucose-dependent arginine-stimulation test only weakly correlated to M/I(clamp) (R(2) approximate 0.25). Thus, 1) insulin secretion is adaptively increased when insulin sensitivity is low in nondiabetic postmenopausal women; 2) beta-cell exocytotic ability shows more efficient adaptation than beta-cell glucose recognition to low insulin sensitivity; 3) impaired beta-cell adaptation (i.e., low DI) is associated with higher 2-h glucose values during OGTT, although other regulatory mechanisms also exist; and 4) indirect surrogate measures of insulin sensitivity only weakly correlate to insulin sensitivity as determined by the euglycemic-hyperinsulinemic clamp.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Issue number||Suppl 1|
|Publication status||Published - 2002|