Hypoglycaemia is a critical condition, particularly in non-diabetic individuals, and is often associated with underlying pathologies like insulinoma, a rare neuroendocrine tumour of the pancreas. Insulinomas are usually benign, but malignant cases, as in this report, present diagnostic challenges. We present a case of a 67-year-old female with recurrent hypoglycaemia, presenting with diaphoresis and palpitations, which were momentarily relieved by consuming sweets. Her random blood sugar (RBS) was critically low (37 mg/dL), and investigations revealed elevated fasting insulin levels and C-peptide. Despite these findings, abdominal imaging was initially unremarkable. The patient was treated with octreotide and later transitioned to diazoxide, which managed her hypoglycaemic episodes. A PET-CT scan revealed a tracer-avid lesion in the pancreas with metastasis to retroperitoneal lymph nodes, confirming the diagnosis of a malignant insulinoma (TNM staging: pT1(m)N1). Histopathology confirmed a well-differentiated neuroendocrine tumour with metastasis. This case highlights the diagnostic difficulties in identifying malignant insulinomas, especially when typical imaging modalities fail to detect the lesion. The patient’s management with octreotide and diazoxide underscores the importance of medical therapy when surgery is contraindicated or tumours are unresectable. This case reinforces the need for prompt diagnosis, particularly in patients with recurrent neuroglycopenic symptoms fitting Whipple’s triad. Advanced imaging techniques like PET-CT play a crucial role in diagnosing insulinomas with atypical presentations, ultimately aiding in effective treatment strategies and improving patient outcomes.