INS and major depressive disorder: The 25 (OH)D level was positively correlated with age, albumin, Hb, ALT, T-bil, calcium, PCS, MCS, and CCI, and negatively correlated with TG, insulin, HOMA_IR, PLT, eGFR, phosphorus, iPTH, the HBM score and depression scores in the univariate association analysis.