TNF and type 1 diabetes mellitus: In the subgroup analysis by age, disease duration, and ethnicity, T1DM patients consistently had significantly increased levels of TNF-α among the three age groups (all P < 0.01) (Fig 3), and three disease duration groups (all P < 0.05) (Fig 4), and four ethnicity subgroups (all P < 0.05) except Asia group (SMD, 0.67; 95%CI, -1.03 to 2.36; P = 0.439) (Fig 5).