Endocrine Abstracts

We present the case of 78-year-old female admitted to our hospital in January 2023 with recurrent hypoglycaemic episodes during fasting periods, particularly overnight and early morning. The patient had impaired hypoglycaemia awareness and cognitive decline. The only past medical history was of hypertension treated with bendroflumethiazide and amlodipine. During hospital stay, she experienced multiple hypoglycaemic episodes. Biochemical investigations revealed non-insulin-dependent hypoglycaemia, as evidenced by suppressed serum insulin (< 7 pmol/l) and C peptide (< 50 pmol/l) at a laboratory glucose of 2.6 mmol/l. IGF-1 levels were marginally low at 4.1 nmol/l (4.4 – 21.8 nmol/l), IGF-2 levels at the upper limit of normal at 28 nmol/l (upper range 28.4 nmol/l) and the IGF-1:IGF-2 ratio was 6.9 (normal <10). Other biochemical parameters were normal. Clinical examination revealed a large mass in the right breast, confirmed on central core biopsy as a malignant phyllodes tumour with extensive stromal overgrowth in the form of undifferentiated spindle cell sarcoma. Staging imaging did not reveal metastasis. Despite high-dose dexamethasone (8 mg/day) and diazoxide (50 mg twice a day), the patient continued to experience hypoglycaemia. Subsequently, she underwent a right mastectomy, leading to complete tumour removal with discontinuation of dexamethasone and diazoxide post-operatively. Flash glucose monitoring (Free Style Libre 2) was used following surgery, revealing no evidence of hypoglycaemia following tumour resection. This case report presents a rare instance of spontaneous recurrent non-insulin dependent hypoglycaemia linked to a malignant phyllodes tumour in the breast. The key clinical lesson is that the combined use of dexamethasone, diazoxide, and flash glucose monitoring enabled safe domiciliary management. However, complete resolution of troublesome hypoglycaemia required surgical resection of the tumour. The exact mechanisms underlying hypoglycaemia in such cases are not fully understood. While IGF-2 secreting sarcomas have been reported, our patient exhibited normal IGF-2 levels