Establishment and validation of an individualized risk prediction nomogram model for gestational diabetes mellitus in pregnant women with hypothyroidism

Objective To establish and validate an individualized risk prediction nomogram model for the occurrence of gestational diabetes mellitus in pregnant women with hypothyroidism.

Methods A total of 160 pregnant women with hypothyroidism were selected as the study subjects, including 85 patients with gestational diabetes mellitus (observation group) and 75 patients with normal blood glucose levels (control group). The age, gravidity, parity as well as pre-pregnancy body mass index, thyroid peroxidase antibody (TPOAb), homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of beta-cell function (HOMA-β), free thyroxine (FT4), free triiodothyronine (FT3) and thyroid stimulating hormone (TSH) were compared between the two groups. Multivariable analysis was used to analyze the risk factors for gestational diabetes mellitusin pregnant women with hypothyroidism. The nomogram model was used to predict the risk of gestational diabetes mellitus in pregnant women with hypothyroidism. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of the nomogram model for gestational diabetes mellitus in pregnant women with hypothyroidism.

Results The age, gravidity, parity as well as pre-pregnancy body mass index, TPOAb, HOMA-IR and HOMA-β were higher in the observation group than in the control group, while pre-pregnancy FT4, FT3 and TSH were lower (P < 0.05). Multivariable analysis showed that older age, gravidity, parity as well as pre-pregnancy body mass index, TPOAb, HOMA-IR and HOMA-β, and lower pre-pregnancy FT4, FT3 and TSH were risk factors for gestational diabetes mellitusin pregnant women with hypothyroidism. The nomogram model prediction showed that older age (28 to 31 years), gravidity (more than 2 times), parity (more than 1 time) as well as pre-pregnancy body mass index (above 24.00 kg/m²), TPOAb (> 421.33 IU/mL), HOMA-IR (> 2.21) and HOMA-β (> 115.66), and lower pre-pregnancy FT4 (< 0.33 ng/dL), FT3 (< 1.65 pg/mL) and TSH (< 0.26 mIU/mL) were risk factors for gestational diabetes mellitus in pregnant women with hypothyroidism. ROC curve analysis showed that the area under the curve of the nomogram model for predicting gestational diabetes mellitus in pregnant women with hypothyroidism was 0.785, indicating good predictive performance.

Conclusion The risk prediction nomogram model has high value in individualized prediction of gestational diabetes mellitus in pregnant women with hypothyroidism.