The glucose tolerance peak parameter revisited. Definition for a novel use in Gestational Diabetes Mellitus confirmation.

Aims: This study aimed to establish a decisive threshold for the Glucose Tolerance peak (GTp) parameter in diagnosing Gestational Diabetes Mellitus (GDM) and to assess its diagnostic efficacy in comparison with other commonly employed indexes in clinical practice.

Materials and methods: Conducted as a prospective observational cohort, the study enrolled 92 pregnant women between 24-28 weeks of gestation, who underwent an Oral glucose Tolerance Test (OGTT) 100 gr. following a positive O'Sullivan screening at La Paz University Hospital. An additional 30-min sample was incorporated to assess the insulin response dynamics during hyperglycaemia. Basal indices and those derived from the OGTT 100 gr. test were computed. Receiver Operating Characteristic (ROC) curves were utilized to determine the optimal cut-off points for the indexes derived from the OGTT. Informed written consent was obtained from all participants.

Results: Significantly greater glucose tolerance, as indicated by GTp, was observed in the Non-Gestational Diabetes (NTG) pregnant group (p < 0.01). The GTp emerged as the parameter with the highest positive predictive value for GDM diagnosis. A cut-off of < 0.36 demonstrated 100% specificity and 75% sensitivity in diagnosing GDM.

Conclusions: GTp, an index derived exclusively from the OGTT peak glycaemia, proves valuable in confirming the presence of GDM. The GTp could be used to confirm the presence of GDM under necessity of a second OGTT as test confirmation in pregnant woman. A cut-off of < 0. 36 has a specificity of 100% and a sensitivity of 75% for the diagnosis of GDM.