MTOR and vitamin D deficiency: 1,25(OH)2D3 protects trophoblasts from high IR primarily by inhibiting mTOR signaling, which may be a potential therapeutic approach for patients with GDM (19).During pregnancy, vitamin D deficiency leads to reduced levels of 1,25(OH)2D3, which diminishes the inhibition of the mTOR signaling pathway, resulting in increased insulin resistance and a higher incidence of GDM.