Phentermine usage was found to be associated with reduced future risk of a new diagnosis of DR with macular oedema (RR 0.462; (95% CI 0.372–0.573), P < 0.001), mild non-proliferative diabetic retinopathy (NPDR) (RR 0.621 (0.508, 0.760), P < 0.001), moderate NPDR (RR 0.567 (0.402, 0.799), P < 0.001), severe NPDR (RR 0.477 (0.233, 0.981), P = 0.003), proliferative diabetic retinopathy (PDR) (RR 0.451 (0.323, 0.629), P < 0.001), vitreous haemorrhage (RR 0.347 (0.200, 0.602), P < 0.001), need for intravitreal anti-VEGF injection (RR: 0.530 (0.354, 0.793), P < 0.001). The gene discussed is VEGFA; the disease is vitreous hemorrhage.