RESUMEN
AIMS: Since glucose levels during oral glucose tolerance test (OGTT) are determined both by insulin sensitivity and insulin secretion, we investigated whether the percentage increment (PG%) of 2-h plasma glucose (2hPG) over fasting plasma glucose (FPG) is related to validated indexes of insulin sensitivity and insulin secretion. METHODS: Using Stumvoll's formulas we calculated estimated insulin sensitivity index and first-phase insulin secretion in 1281 subjects who underwent a standard OGTT. The ratio first-phase insulin secretion/(1/estimated insulin sensitivity index) was considered a surrogate index of ß-cell function. For each subject we calculated PG% using the formula: [(2hPG - FPG)/FPG] × 100. For each glucose tolerance group we formed tertiles based on PG% values. RESULTS: In each glucose tolerance group, ß-cell function was better preserved in lower PG% tertiles, demonstrating a correlation between PG% and insulin resistance. CONCLUSIONS: By a simple calculation, our study allows, expansion of the clinical use of OGTT to recognize subjects liable to further worsening of glucose homeostasis, independent from glucose tolerance groupings.