The aim of this case report is to present a complex case of recurrent pericardial effusions and cardiac tamponade in a young man with diazoxide-responsive congenital hyperinsulinism (CHI), and to explore the rare but documented association between diazoxide and pericardial effusions.
We describe a 25-year-old Indigenous male from regional New South Wales with CHI diagnosed at birth, who presented with recurrent pericardial effusions requiring pericardiocentesis. He was transferred to a tertiary cardiothoracic unit for definitive management with partial pericardiectomy. His care was coordinated by a multidisciplinary team, including endocrinology, cardiothoracic surgery, clinical pharmacy and diabetes education. The patient had been taking diazoxide 300 mg twice daily since childhood, with no dose adjustment since his late teens. His family had opted not to pursue genetic testing, and he had been lost to follow-up following transition from paediatric to adult services. He experienced frequent hypoglycaemic seizures due to lack of treatment efficacy and/or poor adherence and had hypoglycaemia unawareness. From 2017 to 2025, he developed chronic pericardial effusions and ultimately life-threatening cardiac tamponade.
Diazoxide remains the cornerstone of therapy for diazoxide-responsive CHI but is associated with adverse effects including fluid retention, pulmonary oedema, and congestive heart failure [1,2]. Pericardial effusion is a rare complication, with only six cases reported in the literature, predominantly in paediatric populations [3–5]. In several reports, a temporal relationship between diazoxide use and effusion recurrence was observed [6].
Management included initiation of octreotide, itself complicated by liver dysfunction, addition of hydrochlorothiazide and compassionate continuous glucose monitoring. Functional imaging and genetic testing were pursued, with a view to possible subtotal pancreatectomy.
This case underscores a rare but important potential complication of diazoxide therapy and highlights potential management strategies, particularly in adults with long-standing CHI.