BACKGROUND: To investigate the effects of vitamin D and omega-3 fatty acids on glucose and blood lipid metabolism in gestational diabetes (GDM) women. METHODS: A total of 150 patients with GDM aged 18-40 who were admitted to our hospital from May 2019 to December 2020 were enrolled in this study. The subjects were divided into test and control groups according to whether they took vitamin D and omega-3 fatty acids. The test group took 40,000 IU of vitamin D and 8,000 mg of omega-3 fatty acids twice a day. Comparative analysis of the changes in blood glucose and blood lipid levels of the two groups of patients was performed after 6 weeks. The t-test was used to compare the differences between groups, and the chi-square test was used to assess percentage differences. Repeated measures variance was used to analyze the effects of vitamin D and omega-3 fatty acids on insulin metabolism markers and blood lipid profiles. RESULTS: After adjusting for baseline age and weight, it was found that the fasting blood glucose (FBG), fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides (TGs), total cholesterol, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) in the test group were decreased by 0.3±0.2 mmol/L, 1.0±0.6 uIU/mL, 0.2±0.1, 0.3±0.1 mmol/L, 0.5±0.2 mmol/L, 1.1±0.4 mmol/L, and 0.03±0.01 mmol/L, respectively, while homeostasis model assessment of beta cell (HOMA-β) was increased by 0.4±0.1. Compared to the placebo group, the test group's FBG, insulin, HOMA-IR, TGs, total cholesterol, LDL, and VLDL were all significantly decreased, and HOMA-β was markedly improved. However, no notable statistical difference was observed in the change of high-density lipoprotein (HDL) (P>0.05). CONCLUSIONS: Combined supplementation with vitamin D and omega-3 fatty acids for 6 weeks in patients with GDM can effectively reduce blood sugar and blood lipids, improve HOMA-β and insulin resistance, and ultimately effectively improve the glucose and lipid metabolism of patients.