In the univariable logistic regression analysis, age, BMI, MPO-ANCA (or P-ANCA) positivity, BVAS, FFS, white blood cell count, haemoglobin, platelet count, serum albumin, ESR, CRP, and the TyG index were associated with MetS at AAV diagnosis (p < 0.1). The gene discussed is MPO; the disease is anti-neutrophil cytoplasmic antibody-associated vasculitis.