THE COMPARISON OF THE SECOND PHASE INSULIN SECRETION DERIVED FROM ORAL GLUCOSE TOLERANCE TEST AND LOW DOSE GRADED GLUCOSE INFUSION TEST

Abstract

Background: the pathogeneses of type 2 diabetes (T2DM) are impaired insulin action and secretion, including the second phase insulin secretion (SPIS). However, SPIS is difcult to be measured. The study aimed to validate the SPIS derived from the simpler oral glucose tolerance test (OGTT) against the SPIS derived from the more complicated gold standard test, i.e. low dose graded glucose infusion test (LDGGI). Methods: Fourteen participants (3 with normal glucose tolerance, 8 with pre-diabetes and 3 with T2DM) were enrolled. They received both a standard LDGGI and an OGTT. The mathematical method which is called deconvolution was applied in both tests. The slope of the insulin secretion rate (ISR) against glucose levels during the LDGGI was obtained and regarded as the gold standard (SPIS-L). At the same time, the SPIS calculated from OGTT with minimal model was also obtained (SPIS-O). Results: Pearson correlation was used to assess the correlation between SPIS-L and SPIS-O. There was a signicant correlation between SPIS-L and SPIS-O (r = 0.843, p = 0.000). At the same time, a good agreement between the SPIS-L and SPIS-O was also found from the Bland-Altman plot. Conclusion: SPIS-O is highly correlated with the gold standard, i.e., the SPIS-L. Since it is easier to be performed, future researches focusing on SPIS by using OGTT might be expedited.