Small ubiquitin-like modifier 4 gene M55V polymorphism demonstrated a significant association with T2DM susceptibility in the whole population under allelic (OR: 1.18, 95% CI: 1.10–1.28, P = 1.63 × 10−5), recessive (OR: 1.59, 95% CI: 1.14–2.23, P = 0.006), dominant (OR: 0.815, 95% CI: 0.737–0.901, P = 6.89 × 10−5), homozygous (OR: 1.415, 95% CI: 1.170–1.710, P = 0.0003), heterozygous (OR: 1.191, 95% CI: 1.072–1.323, P = 0.001), and additive genetic models (OR: 1.184, 95% CI: 1.097–1.279, P = 1.63 × 10−5) (Figures 1–6; Table 2). The gene discussed is SUMO4; the disease is type 2 diabetes mellitus.