PurposeWe describe a patient with endogenous endophthalmitis caused by Acinetobacter spp. as the first clinical presentation of diabetes mellitus.MethodA 48-year-old otherwise healthy woman was referred with signs and symptoms of acute endophthalmitis in the left eye. Systemic work-up, vitreous tap, and intravitreal antibiotic injection were performed followed by pars plana vitrectomy.ResultsThe laboratory tests confirmed the diagnosis of diabetes mellitus. Vitreous culture was positive for Acinetobacter spp., and the organism was sensitive to colistin. One month after surgery, vision was no light perception, and the eye was phthisical.ConclusionDiagnostic work-up should be performed even in otherwise healthy patients with endogenous endophthalmitis.