Endocrine Abstracts

Introduction: Type 2 diabetes (DM) is characterized by both insulin resistance and β-cell dysfunction. The oral disposition index (DIo), a measurement of β-cell function and insulin sensitivity, is considered the best predictor of progression to a worse GTS, although it was not well tested for regression to a better GTS.

Objectives: To assess the validity of DIo and determine whether DIo predicts regression to a better GTS.

Methods: At first evaluation of a longitudinal study, patients from an outpatient clinic (n=103; 54.8±11.4 years; females 69.9%) were submitted to a 75-g OGTT and classified according to different degrees of glucose tolerance in (PDM (n=49) and DM (n=54)). Insulin sensitivity was estimated as 1/fasting insulin and β-cell function as the ratio of the change in insulin to the change in glucose from 0 to 30 (ΔI0–30/ΔG0–30). The DIo was calculated as (ΔI0–30/ΔG0–30 × 1/fasting insulin). Patients were followed-up by 25 (15–38) months (median (P25–P75)) and their data were recollected. Patients were classified as regressors and non-regressors to a better GTS.

Results: ΔI0–30/ΔG0–30 demonstrated a curvilinear relationship with 1/fasting insulin. The confidence limits for the slope of the log-transformed estimates included -1 for DIo for regressors and non-regressors, consistent with a hyperbolic relationship. While at follow-up 22.2 and 38.9% of patients with DM respectively regressed to NGT and PDM, 26.5% of patients with PDM regressed to NGT and 14.3% progressed to DM.

Conclusion: A total of 44.7% of patients regressed to a better glucose tolerance status while participating in a program with multiple interventions for the treatment of hyperglycemia. Although the DIo was not able to predict these changes, a composite measure of β-cell function was proved to be reproducible and could be applied for DM research in the Brazilian population.