Exploring insulin resistance and pancreatic function in individuals with overweight and obesity: Insights from OGTTs and IRTs.

To investigate insulin resistance and pancreatic β-cell function in overweight or obese people under the same glucose tolerance conditions. The subjects were categorized based on the results of the oral glucose tolerance test (OGTT) and the BMI classification criteria. Basal and postprandial glucose concentrations, insulin concentrations, pancreatic β-cell function (HOMA-β), the insulin resistance index (HOMA-IR), and the insulin early secretion index (ΔI30/ΔG30) were compared between the different weight groups. Among individuals with similar glucose tolerances, those in the obese group presented higher HOMA-β, HOMA-IR, and ΔI30/ΔG30 values than did those in the normal weight and overweight groups. Additionally, in individuals with normal glucose tolerance and early diabetes, OGTT 1-h plasma glucose concentrations demonstrated a stronger correlation with early insulin secretion across different body weights. When the same glucose-tolerant population was grouped by weight, OGTTs were significantly less different than IRTs. Therefore, integrating both tests is the optimal approach. In individuals with preobesity, there is an increase in pancreatic β-cell function to maintain normal blood glucose levels. As the disease progresses, obesity substantially increases insulin resistance, which acts as a disease-promoting factor. Furthermore, OGTT 1-h plasma glucose concentrations are strongly correlated with insulin secretion in normal or early diabetic populations.