Sudden ‘cure’ of type two diabetes due to pancreatic insulinoma: A case report

Abstract

Insulinomas are rare tumors of the islet cells of the pancreas and are the most common cause of endogenous hyperinsulinism. Although they usually present with symptoms of hypoglycemia, sometimes they can have vague symptoms. We present the case of a 62-year-old diabetic female who was diagnosed with a large insulinoma after being investigated for the 'cure' of her diabetes. We also review the literature regarding insulinomas in patients with diabetic. A 62-year-old, obese woman with type 2 diabetes mellitus was initially investigated for an unexplained normalization of her blood glucose levels after the cessation of antidiabetic medication due to an episode of severe hypoglycemia. She remained without antidiabetics for three months maintaining normoglycemia, and thereafter, she started experiencing frequent but less severe hypoglycemic episodes. She did not change her diet habits or level of activity and did not lose any weight. The patient underwent further investigation with a supervised 72 h fasting test, which resulted in the biochemical diagnosis of endogenous hyperinsulinism. Imaging studies revealed the presence of a large insulinoma in the head of the pancreas. Finally, the patient underwent a pylorus preserving Whipple procedure, which reversed the aforementioned 'normalization' of glucose levels and the underlying diabetes mellitus reappeared. Insulinomas are rare tumors causing hypoglycemia. Even more rarely are found in diabetic patients, making the diagnosis more challenging and probably delayed, as the symptoms are masked by the presence of diabetes, thereby leading to a more advanced disease diagnosis.

Case Report: Insulinoma Co-Existing With Type 2 Diabetes – Advantages and Challenges of Treatment With Endoscopic Ultrasound-Guided Radiofrequency Ablation

“…Moreover, in patients with diabetes, even if hypoglycaemic symptoms are present, they are often attributed to iatrogenic causes such as the use of insulin therapy or insulin secretagogues. As a result, this delay in diagnosis may lead to a higher likelihood of progression of the underlying insulinoma to more advanced disease, larger tumour size and a higher rate of malignancy which has been reported as high as 25% compared to the usual quoted rate of 10% ( 5 ).…”

“…Insulinoma is an uncommon neuroendocrine tumour (NET) with an incidence of 4 cases per 1 million person-years ( 1 ). Although the clinical presentation of insulinoma and type 2 diabetes (T2D) may seem contradictory, with the former predominates with recurrent refractory hypoglycaemia while the latter is characterized by fasting and post-prandial hyperglycaemia, their coexistence has been infrequently reported ( 2 – 5 ). In a retrospective study conducted by the Mayo clinic, out of the 313 cases of insulinoma over a 65-year period, there was only one case of insulinoma diagnosed in the background of pre-existing T2D ( 3 ).…”