The haplotype analysis was further conducted and the results indicated that Crs1062033Grs17601876Ars3751599 in CYP19A1 played a protective role (OR = 0.48, 95% CI = 0.25–0.91, P = 0.026) in T2DM patients with diabetic retinopathy. The gene discussed is CYP19A1; the disease is type 2 diabetes mellitus.