The following is a summary of “β-Cell Function and Insulin Sensitivity in Youth With Early Type 1 Diabetes From a 2-Hour 7-Sample OGTT,” published in the June 2023 issue of Endocrinology & Metabolism by Galderisi, et al.

For a study, researchers sought to validate a 2-hour 7-point oral glucose tolerance test (OGTT) protocol against the standard 3-hour 9-point OGTT and to investigate the impact of early sampling frequency variations on estimates of β-cell responsiveness and insulin sensitivity (SI). The oral minimal model was commonly used to assess β-cell responsiveness and SI based on glucose, C-peptide, and insulin measurements during a 3-hour OGTT. However, a shorter and simplified protocol would be beneficial for clinical use.

A retrospective analysis was conducted on data from 15 lean youth with stage 1 type 1 diabetes (T1D; ≥ 2 islet autoantibodies with no dysglycemia) who underwent a 3-hour 9-point OGTT. The oral minimal model was employed to calculate β-cell responsiveness (φ_total) and SI, allowing for the evaluation of β-cell function through the disposition index (DI = φ_total × SI). The 2-hour 7-point and 5-point OGTT protocols were compared to the 3-hour 9-point gold standard to assess the agreement of estimates for φ_total, its dynamic and static components, SI, and DI using different sampling strategies.

The 2-hour estimates for the disposition index exhibited a strong correlation with the 3-hour measurements (r = 0.975; P < .001), with similar results observed for β-cell responsiveness and SI (r = 0.997 and r = 0.982; P < .001, respectively). The agreement between the 7-point 2-hour and 9-point 3-hour protocols fell within the 95% CI on the Bland-Altman plot, with median differences of 16.9% (−35.3 to 32.5), 0.2% (−0.6 to 1.3), and 14.9% (−1.4 to 28.3) for DI, φ_total, and SI, respectively. Conversely, the 5-point protocol did not provide reliable estimates of the dynamic and static components of φ.

The 2-hour 7-point OGTT protocol is a valid and reliable method for assessing β-cell responsiveness, SI, and DI in individuals with stage 1 T1D. Incorporating these analyses into current 2-hour OGTTs may improve the accuracy of quantifying progression risk in the early stages of T1D.

Source: academic.oup.com/jcem/article-abstract/108/6/1376/6955789?redirectedFrom=fulltext