Comparing Simple Insulin Sensitivity Indices to the Oral Minimal Model Postexercise.

Area of Science:

• Exercise Physiology
• Metabolic Health
• Insulin Resistance

Background:

• Insulin sensitivity (Si) is crucial for metabolic health, and exercise is known to improve it.
• Accurate measurement of Si changes in response to exercise is essential for understanding its benefits.
• Various indices exist to estimate Si, but their comparability, especially after exercise, needs clarification.

Purpose of the Study:

• To compare insulin sensitivity (Si) changes derived from fasting and oral glucose tolerance test (OGTT) indices with those from the oral minimal model (OMM).
• To evaluate the effectiveness of different Si indices following moderate-intensity exercise (MIE) and high-intensity exercise (HIE) in prediabetic individuals.

Main Methods:

• Eighteen prediabetic subjects underwent control, MIE (∼50% VO2peak), and HIE (∼80% VO2peak) conditions.
• Insulin sensitivity was measured using multiple OGTT-based and fasting indices, compared against the OMM.
• Statistical analyses included ANOVA and Pearson's correlations to assess relationships between changes in Si (ΔSi) indices.

Main Results:

• Exercise significantly increased Si based on OGTT indices (11-85%), but fasting indices showed no change (MIE) or a decrease (HIE).
• OGTT and fasting indices underpredicted exercise-induced ΔSi-OMM by approximately 40% and 90%, respectively.
• ΔSi-OMM moderately correlated with OGTT-based indices after MIE but not with any index after HIE.

Conclusions:

• While most Si indices indicate post-exercise improvement, significant variability exists between them.
• OGTT and fasting indices show limited correlation with the OMM, particularly after high-intensity exercise.
• Caution is advised when interpreting the insulin-sensitizing effects of exercise using standard OGTT and fasting indices.