PMON315 Hyperglycemia Dilemma: Concomitant Type 1 Diabetes Mellitus and Cushing's disease

INTRODUCTION: Type 1 diabetes (T1DM) is an autoimmune condition causing destruction of insulin-producing pancreatic beta cells. About a third of patients present with DKA at diagnosis. Insulin is mainstay therapy to achieve glucose control. Glucose hemostasis is affected by several factors. Conditions including acute illness or endocrinopathy such as Cushing's disease can cause hyperglycemia. We present a case of a pediatric patient with T1DM and difficult to control hyperglycemia due to concomitant hypercortisolism. CASE: The patient is an eleven-year-old male, who first presented in DKA at the age of 10. HgA1c at diagnosis was 17.9%. GAD65 and IA2 antibodies were positive. Compliance to medications as well as post-hospital follow-up has been an issue. At his initial follow-up visit, 8 months after diagnosis, they reported adherence to prescribed insulin regimen although his A1c was 11.3%. Insulin dose was adjusted based on current A1c level and documented glucose monitor readings. 3 months after, improvement of A1c was documented at 10.7%. He however complained of eye swelling and noted to have elevated blood pressure. Due to concerns of nephrotic syndrome he was referred to nephrology. His renal function test and urine micro-albumin came back normal. He was started on Lisinopril 5mg daily but eventually switched to amlodipine 5mg daily to control his blood pressure. In the following 14 months, nephrology noted that his hypertension was difficult to control in spite of optimizing medications. He was eventually admitted for severe headache. Significant exam on admission revealed moon facies, buffalo hump, striae on his extremities. A CT scan revealed pituitary macroadenoma 1.1×2cm. TSH was slightly low, FT4 normal. Growth hormone was also elevated. ACTH was 38 pg/ml (n 7.2-63 pg/ml)and serum cortisol was 7.1mcg/dl (n 3-22 mcg/dl). 24hr urine cortisol sent but was still pending. The rest of the pituitary work up was normal. Patient was scheduled for transsphenoidal surgery. A repeat 24-hour urine cortisol was again sent prior to surgery assuming initial test was lost. Interestingly, the initial 24-hour Urine free cortisol came back significantly elevated at 1,304 mcg (normal 2.3-37mcg) and urine free cortisol is . Pathology came back as pituitary apoplexy. 24-hour urine cortisol right before surgery came back undetectable confirming this. CONCLUSION: Non-adherence to medication is a common reason for persistent hyperglycemia in T1DM but providers should be vigilant of other possible etiologies. Continued follow-up and detailed physical exam to check for clues such as hypertension, striae, buffalo hump, and bruising can lead to unmasking a secondary etiology. We present the first reported case of type 1 diabetes and Cushing's disease from a functional pituitary macro-adenoma that subsequently develop pituitary apoplexy. It is important to note that 24 urine cortisol remains the gold standard for diagnosis regardless of normal serum cortisol levels. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.