Endocrine Abstracts

Case Presentation: A 58-year-old man with type 2 diabetes mellitus (diagnosed five years earlier) on metformin, dapagliflozin, and amlodipine presented with progressive symptoms of nocturnal hyperglycaemia which started 0300hrs and lasted to 1100hrs on a daily basis. Continuous glucose monitoring confirmed glucose levels of 15–20 mmol/l between those hours followed by relative euglycaemia thereafter. Clinic review confirmed the concomitant presence of hypertension, palpitations, sweats with blood pressure surges up to 240 mmHg systolic. These likewise resolved by 11am each day. Plasma normetanephrines were elevated at 6,247 pmol/l (normal <1,180pmol/l). HbA1c was 56 mmol/mol, with MIBG scintigraphy demonstrating a 5 0× 4.1 cm right adrenal mass. Pituitary profile was unremarkable (ACTH 13 ng/l; random cortisol 246 nmol/l), and 24-hour salivary cortisol and cortisone were normal. He underwent right robotic adrenalectomy. Histopathology confirmed phaeochromocytoma with Ki-67 index 10% and PASS score 6. SDH staining was negative for SDH mutation. Postoperatively, his HbA1c improved to 52 mmol/mol, and all antihyperglycemic medications were discontinued.

Discussion: This case describes an unusual pattern of hyperglycaemia limited to the hours of 0300-1100hrs which has not been previously described. The pattern raises the hypothesis of ACTH or CRH receptor expression within the tumour contributing to nocturnal activation and hyperglycaemia. Further histopathological and molecular studies, including RNA analysis for ACTH and CRH receptors, are underway.

Conclusion: This is a unique presentation of phaeochromocytoma characterised by nocturnal hypertensive and hyperglycaemic episodes, highlighting the need to consider atypical circadian behaviour in catecholamine-secreting tumours.