Bilateral diabetic papillopathy developed after starting insulin treatment. Potential toxic effect of insulin? A case report

Background: Diabetic papillopathy is a complication of diabetes. It presents with edema, uni or bilateral and vascular alteration of the anterior optic nerve. Often this complication is observed in patients with severe diabetic retinopathy, but is rarely observed in isolated form. Some authors believe that diabetic papillitis is a particular form of non-arteritic anterior ischemic optic neuropathy (NAION). But there is important evidence that confers an inflammatory component to diabetic papillopathy. We report in this work a rare case of isolated acute bilateral diabetic papillopathy developed in a diabetic patient after adding the insulin to the oral hypoglycemic therapy. Case presentation: Male patient, 49-years-old, diabetic type 2, with altered glycemia at follow up, with clinical history of HbA1c 8% to 12% in the last 2 years, on oral hypoglycemic therapy for 10 years. He never had a history of diabetic retinopathy. At the last check-up, this patient presented bilateral papillopathy, without reduction of visual acuity bilaterally. The patient reports he added 10 days before the insulin therapy to the oral hypoglycemic therapy, under medical supervision. Hematochemical and serological tests were requested, which excluded the presence of inflammatory and infectious diseases. The brain magnetic resonance imaging (MRI) with gadolinium excluded the hypothesis of optic neuritis or intracranial hypertension. Cardio-circulatory tests were normal. Fluorescein angiographic examinations and optical coherence tomography (oct) confirmed the bilateral edema and the thickening of optic nerve without other retinal damage. Therefore he was diagnosed with bilateral diabetic papillopathy. Then, diabetologists added pump insulin treatment to the oral hypoglycemic therapy. After 2 months, his blood sugar levels and HbA1C improved and papillopathy regressed. Conclusion: We have reported a rare case of bilateral acute diabetic papillopathy associated with the addition of insulin to the oral hypoglycemic therapy. A randomized control study with diabetic patients, would be useful to verify the possible injuries of the optic nerves during the delicate transition to insulin therapy.