C1QTNF9 and diabetes mellitus: Given the high heterogeneity, subgroup analysis was conducted based on the following four factors: (1) key study characteristics (year of publication, patient age, and BMI); (2) relevant clinical biochemical markers [total cholesterol (TC), low-density lipoprotein (LDL), and high-density lipoprotein (HDL)]; (3) intimal thickness; (4) concentrations of CTRP9 and IL-6; (5) smoking, hypertension, and diabetes.