Clinical and biochemical factors associated with insulin therapy in gestational diabetes: The role of OGTT-based groups.

Gestational diabetes mellitus (GDM) represents one of the most common metabolic disorders of pregnancy. This study aimed to identify clinical and biochemical factors associated with antenatal insulin therapy, focusing on the association with oral glucose tolerance test (OGTT)-based phenotypes. Retrospective observational study among GDM women, divided according to their treatment (nutritional therapy (NT) or insulin therapy). GDM was classified into three phenotypes based on OGTT results: isolated fasting hyperglycaemia (IFH-GDM), isolated post-load hyperglycaemia (IPH-GDM) and combined hyperglycaemia (CH-GDM). Maternal demographic, obstetric and biochemical data were analysed. Multivariable logistic regression analysis was performed to identify factors independently associated with insulin therapy. Among 458 women, 39.3% required insulin therapy. Independent factors associated with the use of insulin therapy included pre-pregnancy obesity (odds ratio (OR) 2.07, 95% CI: 1.21-3.55), spontaneous miscarriage history (OR 1.89, 95% CI: 1.21-2.93), pregestational hypothyroidism (OR 2.63, 95% CI: 1.08-6.42), GDM diagnosis at 24-28 weeks versus earlier diagnosis (OR 0.45, 95% CI: 0.28-0.72), and GDM phenotype. Compared with IFH-GDM, IPH-GDM was associated with a lower risk of insulin therapy (OR 0.51, 95% CI: 0.31-0.84), whereas CH-GDM was associated with a higher risk (OR 1.90, 95% CI: 1.10-3.31). In conclusion, women with fasting and combined hyperglycaemia represent the highest-risk group for insulin therapy. Integrating OGTT-based phenotypes with clinical risk factors was associated with increased likelihood of insulin therapy requirement and may support individualized clinical assessment.