SUN-614 - Bilateral Cranial Nerve Palsies as the Initial Presentation of Type 2 Diabetes Mellitus

A 70-year-old man with a history of hypertension, hyperlipidemia, and hypothyroidism presented to the emergency department with one week of progressive blurry vision and headache, followed by new-onset diplopia. On admission, he was hypertensive (blood pressure in the 180s/110s) with normal heart rate (heart rate 97 bpm) and hyperglycemia (serum glucose 205 mg/dL). He was alert and oriented, without scleral erythema or proptosis.
Neurologic examination revealed impaired adduction of the right eye and downward deviation of the left eye, consistent with a right cranial nerve (CN) VI palsy and a left CN IV palsy, without additional focal deficits. Initial laboratory evaluation, including complete blood count, basic metabolic panel, lipid panel, and thyroid-stimulating hormone, was largely unremarkable except for markedly elevated hemoglobin A1c (11.5%), serum glucose (205 mg/dL), and total cholesterol (393 mg/dL), supporting a new diagnosis of uncontrolled type 2 diabetes mellitus.
Non-contrast CT of the head showed no acute intracranial pathology, with only mild chronic small-vessel ischemic changes. Despite blood pressure optimization, visual symptoms persisted. Further evaluation by neurology and ophthalmology confirmed bilateral cranial nerve palsies. CT maxillofacial imaging with intravenous contrast, MRI brain, and MR venography were unremarkable. Infectious and rheumatologic evaluations were negative, and cerebral venous thrombosis, vasculitis, infectious sinus disease, and cerebrovascular accident were ruled out.
Endocrinology was consulted, and insulin therapy was initiated using multiple daily injections (total daily dose ~72 units). The patient was discharged in stable condition. Over subsequent months, he maintained good glycemic control with gradual improvement in ocular motility, achieving complete neurologic recovery within one year, without residual neurologic deficits.
This case highlights an unusual presentation of diabetes mellitus with simultaneous bilateral cranial nerve palsies at initial diagnosis. Diabetic cranial neuropathy is uncommon and typically occurs in patients with long-standing disease, most often affecting cranial nerves III, V, and VI, likely due to microvascular ischemic injury from diabetic vasculopathy. Bilateral involvement at disease onset is particularly rare, making this case notable. Importantly, the patient achieved progressive and complete neurologic recovery with improved glycemic control, supporting the favorable prognosis of diabetic cranial neuropathy when metabolic abnormalities are promptly addressed. This case emphasizes the importance of considering diabetes mellitus in the differential diagnosis of cranial nerve palsies and highlights the potential for full neurologic recovery with appropriate metabolic management.

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