Sixth-nerve palsy in a patient with uncontrolled type 1 diabetes

Oculomotor palsy is one of the most frequent neuro-ophthalmologic complications in patients with diabetes. Specifically, sixth nerve palsy is the most common. A 51-year-old female with a past medical history of type 1 diabetes on insulin and hypertension presented with complaints of worsening headache and diplopia. Physical exam was remarkable for recurrent sixth-nerve palsy. Patient was hemodynamically stable. Labs showed blood glucose of 367 mg/dL (70–100 mg/dL), an anion gap of 2 mmol/L (3–13 mmol/L), creatinine of 0.61 mg/dl (0.66–1.25 mg/dL), sodium of 129 mmol/L (135–145 mmol/L), and potassium of 4.4 mmol/L (3.5–5.1 mmol/L). Her hemoglobin A1C was 13.0 % Her complete blood count shows a white blood cell count of 6000/μL (3600-10,700/μL) and a hemoglobin of 14 g/dL (13.0–18.0 g/dL). Magnetic resonance venography of the head was negative for cerebral venous sinus thrombosis and magnetic resonance imaging of the brain was negative for acute abnormalities. Blood glucose readings improved during hospitalization after optimizing her insulin regimen. She was recommended to follow-up with outpatient endocrinology to discuss use of an insulin pump to better control her diabetes. Sixth-nerve palsy is a frequent but lesser-known neuro-ophthalmologic complication of poorly controlled diabetic patients. Studies have shown a higher incidence of diabetes in patients with sixth-nerve palsy, warranting a more focused medical evaluation along with close observation and tighter control of blood glucose levels and hemoglobin A1C. •Neuropathy of the cranial nerves, despite being a rare entity in diabetes mellitus, is problematic from a diagnostic and therapeutic point of view.•Although the prognosis is excellent, it remains a diagnosis of exclusion and retrospection.•Ischemic events or stroke should be ruled out with appropriate imaging.•Sixth-nerve palsy is a frequent but lesser-known near-opthalmologic complication of poorly controlled diabetic patients.•Studies have shown a higher incidence of diabetes in patients with sixth-nerve palsy.•Patients with cranial nerve palsy and diabetes mellitus require close observation and tight glycemic control.•Clinical relevance: This case shows evidence of a unique visual finding of sixth-nerve palsy in a patient with diabetes mellitus.•It explains the importance of glycemic control in patients with cranial nerve palsy, not only in those with diabetic retinopathy.