A 52-year-old man with type 2 diabetes mellitus (HbA1c 9.2%) presents with gradual painless loss of vision in both eyes over the past 6 months. He reports no floaters or flashes of light. On examination, visual acuity is 6/24 in both eyes. Dilated fundoscopy reveals multiple dot-blot hemorrhages, hard exudates in a circinate pattern around the macula, and microaneurysms scattered across the posterior pole. There is no evidence of neovascularization or vitreous hemorrhage. What is the most appropriate next step in management?