To analyze the correlation between the levels of serum inflammatory factors, homocysteine (Hcy), cystatin C (CysC) of the women with gestational diabetes mellitus (GDM) and their insulin resistance, and to study their values for predicting GDM. Methods: 84 pregnant women with diagnosed GDM were selected in study group, and 84 healthy pregnant women who received regular prenatal examination were selected in control group from April 2018 to February 2020. Detections of the levels of serum interleukini-6（IL-6), tumor necrosis factor-α（TNF-α), and high sensitivity C-reactive protein（hs-CRP), Hcy, and CysC, the fasting blood glucose（FBG), and the fasting insulin（FINS) of the women in the two groups were detected, and the value of homeostasis model assessment insulin resistance index（HOMA-IR) of the women in the two groups was calculated. According to the treatment during pregnancy, the women in the study group were divided into group A (women with glycosylated hemoglobin >6%) and group B (women with glycosylated hemoglobin ≤6%). The levels of serum IL-6, TNF-α, hs-CRP, Hcy, and CysC of the women after treatment were compared between group A and group B. Results: The levels of FBG, FINS, and HbA1c, and the HOMA-IR value of the women in the study group were significantly higher than those of the women in the control group, and the levels of IL-6, TNF-α, HSCRP, Hcy, and CysC of the women in the study group were also significantly higher than those of the women in the control group (all P<0.05). After treatment, the levels of IL-6, TNF-α, hS-CRP, Hcy, and, CysC of 31 women in group A were significantly higher than those of 53 women in group B (P<0.05). The levels of serum IL-6, TNF-α, HS-CRP, Hcy, and CysC of the women in the study women were positively correlated with their FBG and FINS levels, and HOMA-IR value (all P<0.05). ROC curve analysis showed that the levels of IL-6, TNF-α, HS-CRP, Hcy, and CysC  of the women had certain value for predicting their GDM occurrence, and the combination of the detections of the levels of IL-6, TNF-α, HS-CRP, Hcy, and CysC  of the women had the highest predictive value, which AUC, sensitivity, and specificity were 0.963, 96.0%, and 98.1%, respectively. Conclusion: The serum levels of inflammatory factors, Hcy, and CysC of the pregnant women with GDM are closely related to their insulin resistance, which have certain value for predicting their GDM in clinic.