To analyze the diagnostic efficacy the levels of thyroxine antibody (TPOAb), glycosylated hemoglobin (HbA1c), and the value of homeostasis model assessment of insulin resistance (HOMA-IR)for gestational diabetes mellitus (GDM). Methods: A total of 131 pregnant women were selected and were divided into group A (72 women with GDM)and group B (59 women without GDM)according to the gold standard results of diagnosing GDM from January 2019 to June 2022. The serum thyroid hormone related indicators, the HbA1c level, and the HOMA-IR value of the women in the two groups were observed, and the efficacy of which for diagnosing GDM was analyzed. The incidences of adverse pregnancy outcomes of the women in the two groups were observed. Results: The level of free tetriodothyronine (FT4)of the women (9.45±2.02 pmol/L)in group A was significantly lower than that (10.63±2.35 pmol/L)of the women in group B. The serum HbA1c level ［(5.82±1.51)%］, and the HOMA-IR value (2.47±0.52)of the women in group A were significantly higher than those ［（4.26±1.24）%、1.55±0.61）］ of the women in group B (all P<0.001). The receiver operator characteristic curve analysis had showed that the area under the curve (0.931)of the combined detections of the levels of serum HbA1c and FT4, and the HOMA-IR value of the women for diagnosing their GDM was higher than that of the FT4 level (0.746), the HbA1c level (0.789), or the HOMA-IR value (0.652)alone. The sensitivity and the specificity of the combined detections of the levels of serum HbA1c and FT4, and the HOMA-IR value of the women for diagnosing their GDM were 82.0% and 88.0%. The rate of adverse pregnancy outcomes (37.5%)of the women in group A was significantly higher than that (13.6%)of the women in group B (P<0.05). Conclusion: The combined detections of the levels of serum HbA1c and FT4, and the HOMA-IR value of the women for diagnosing their GDM has high efficiency, and which can provide reference for early intervention of GDM.