Abstract:
Whole body insulin sensitivity ( I S ) can be measured with the Glucose Clamp
(GC) and is regarded as a gold standard. However, this method is laborious and
expensive. The Oral Glucose Tolerance Test (OGTT) is much simpler and less costly
and is a commonly used method for measuring glucose kinetics and insulin sensitivity
under physiological conditions. However, a major drawback of OGTT is that the rate
of glucose appearance (Ra) is unknown.
The aim of this study was to develop a novel insulin sensitivity index using the
OGTT data and the minimal model with compensation for the rate of appearance of
orally administered glucose into plasma. Ra is described in terms of glucose
absorption. In this thesis is called “the Absorption Minimal Model” (AMM). In this
study, 137 subjects with various degrees of glucose tolerance (normal glucose
tolerance (NGT), impaired glucose tolerance test (IGT), and diabetes mellitus (DM))
underwent a glucose clamp and 75-g OGTT. The model was validated with the clamp
measurements. I S -AMM was also compared with other indexes that are frequently
used to measure insulin sensitivity during an OGTT.
The comparison between mean values of insulin sensitivity clamp
I S and I S -
AMM showed that I S -AMM was a good representative of clamp
I S . The correlation
between the two indexes was high and satisfactory (r = 0.89, p<0.0001). Moreover, the
relationship between the proposed index and the rate of glucose sorption was
confirmed by testing the proposed index on different databases. The AMM approach
could be a powerful tool for estimating insulin sensitivity to assess the efficacy of a
given therapy in diabetic patients.