In the subgroup analysis stratified by ethnicities among the Caucasian population, a significant association between TAP1 I333V gene polymorphism and T1DM was found in allelic (OR: 1.30, 95% CI: 1.09–1.55, P = 0.004), dominant (OR: 1.330, 95% CI: 1.079–1.640, P = 0.008), homozygous (OR: 1.854, 95% CI: 1.082–3.176, P = 0.022), heterozygous (OR: 1.351, 95% CI: 0.889–2.054, P = 0.029) and additive genetic models (OR: 1.297, 95% CI: 1.088–1.548, P = 0.004). The gene discussed is TAP1; the disease is type 1 diabetes mellitus.