Oral Glucose Tolerance Test

OGTT-based insulin sensitivity indices are surrogates for the euglycaemic clamp, which is the reference method but too burdensome for routine clinical use. High-risk women undergo an early OGTT at weeks 16 to 18 of gestation, while standard screening occurs at weeks 24 to 28. Blood is collected at four time points (0, 30, 60, and 120 minutes after glucose ingestion) to measure plasma glucose, insulin, and C-peptide. Because sarcopenia combined with GDM may represent a peculiar metabolic condition, some standard insulin sensitivity indices may be unreliable in this population. OGTT data will be mathematically modelled to calculate insulin sensitivity, insulin secretion, pancreatic beta-cell function, and insulin clearance.