Insulin-Secreting Tumours (Insulinoma): Understanding Causes, Symptoms, and Diagnosis in Adults

Insulin secreting tumours, commonly known as insulinomas, are rare pancreatic neuroendocrine growths that produce excessive amounts of insulin. Although uncommon, they are one of the most important causes of recurrent low blood sugar (hypoglycemia) in adults who do not have diabetes. These tumours typically originate from the beta cells of the pancreas and are usually small, solitary, and benign, but their impact on metabolism can be significant.

The hallmark of an insulinoma is inappropriate insulin release even when blood sugar levels are already low. This leads to episodes of dizziness, confusion, sweating, trembling, blurred vision, and, in severe cases, loss of consciousness. Individuals may notice symptoms especially after fasting, prolonged physical activity, or missing meals. Because symptoms can mimic many other disorders, insulinomas are often overlooked or misdiagnosed for long periods.

Diagnosing an insulin secreting tumour involves carefully evaluating blood glucose, insulin, C-peptide, and proinsulin levels particularly during episodes of hypoglycemia. A supervised fasting test is often used to reproduce symptoms safely while confirming biochemical findings. Once biochemical evidence is established, imaging techniques such as endoscopic ultrasound, CT scans, MRI, or specialized nuclear medicine scans help pinpoint the exact tumour location within the pancreas.

Understanding why these tumours form is still an area of active research. Most insulinomas develop sporadically, though a small percentage are associated with genetic conditions like Multiple Endocrine Neoplasia type 1 (MEN1). Regardless of the underlying cause, early recognition is crucial because prolonged hypoglycemia can have serious consequences for the brain and nervous system.

Treatment is tailored to the individual. For many patients, surgical removal offers a definitive cure, especially when the tumour is localized and accessible. When surgery is not an option, medical therapies may help stabilize blood sugar and reduce symptoms. Advances in minimally invasive procedures and targeted therapies continue to improve outcomes, making long-term management increasingly effective.

Awareness of insulin-secreting tumours is essential for both patients and healthcare providers. Recognizing the subtle pattern of symptoms and understanding the metabolic effects of excess insulin can lead to faster intervention, better diagnostic accuracy, and improved quality of life. Knowledge about this rare condition empowers individuals to seek appropriate medical attention and make informed decisions about their health.