First-Trimester Lipid Profile and Subsequent Gestational Diabetes Mellitus: A Retrospective Case–Control Study

Background/Objectives: Gestational diabetes mellitus (GDM) is a common metabolic complication of pregnancy, and identifying women at increased risk early in gestation may facilitate closer surveillance and timely preventive strategies. This study aimed to investigate the association between first-trimester maternal lipid profile parameters and subsequent GDM and to evaluate their discriminatory performance for GDM. Methods: This retrospective case–control study included singleton pregnancies followed at İzmir Kâtip Çelebi University Atatürk Training and Research Hospital between January 2015 and December 2019. Serum lipid parameters obtained between 11 + 0 and 13 + 6 weeks of gestation were retrospectively retrieved and compared between women who subsequently developed GDM and those who did not. Associations with GDM were evaluated using binary logistic regression, and discriminatory performance was assessed using receiver operating characteristic (ROC) curve analysis. Results: Of 367 women assessed for eligibility, 336 were included in the final analysis (201 with GDM and 135 controls). Women who developed GDM had higher triglyceride levels (median: 138 vs. 103 mg/dL; p < 0.001) and LDL-C/HDL-C ratios (2.339 ± 0.695 vs. 2.174 ± 0.774; p = 0.042) and lower HDL-C levels (median: 47 vs. 53 mg/dL; p = 0.002). Triglyceride concentration was significantly associated with GDM (OR = 1.010, 95% CI: 1.005–1.014; p < 0.001). Triglycerides demonstrated an AUC of 0.687; a cut-off of >125 mg/dL yielded 62.69% sensitivity and 74.81% specificity. Conclusions: First-trimester maternal lipid alterations, particularly higher triglyceride levels, were associated with subsequent GDM. However, triglycerides demonstrated only modest discriminatory performance and should not be considered a stand-alone predictor. Routinely available lipid parameters may provide additional information for early GDM risk stratification.