We report the case of a 42-year-old man with uncontrolled diabetes mellitus who presented to us with diminution of vision in both eyes for the past two years. On examination, both eyes showed features of high-risk proliferative diabetic retinopathy and the patient was advised of panretinal photocoagulation (PRP). He underwent the first sitting of PRP in both eyes. On the following day, he developed hypopyon uveitis in the right eye. He was treated with topical steroid and cycloplegic, and complete resolution of hypopyon was achieved over the next three days. This case highlights the importance of adequately controlled diabetes mellitus before PRP. Hypopyon uveitis could be a complication of PRP in patients with uncontrolled diabetes mellitus who respond to frequent topical steroid and cycloplegic.