The number of HIF-1α-positive cells in the retinas was 20.26±1.29/section in the control group, 32.16±1.49/section in the STZ-induced diabetes group, 21.73±1.56/section in the STZ-induced diabetes and 250 mg/kg betaine-treated group and 23.19±1.31/section in the STZ-induced diabetes and 500 mg/kg betaine-treated group. The gene discussed is HIF1A; the disease is diabetes mellitus.