Endocrine Abstracts

Insulinomas are rare neuroendocrine tumors (NETs) of the pancreas with an incidence of four per 1 million persons per year. The co-existence of diabetes mellitus (DM) and insulinoma is very rare. We report a case of 73 year old women with malignant insulinoma and type 2 DM. A 73 year old woman with type 2 diabetes was referred to our clinic for recurrent and severe hypoglycemia especially in the early morning hours. The patient had a history of type 2 DM for 10 years. Although oral antidiabetic drugs are stopped, hypoglycemic episodes persistenly recurred. The patient was hospitalized to investigate the cause of hypoglycemia. At the second day in hospital, the patient experienced a symptomatic hypoglycemic episode. Blood samples taken at that time revealed a low plasma glucose (23 mg/dl) accompanied with elevated insulin and c- peptide levels (17.4 mIU/l, 3,73 ng/l). Cortisol level was 26 μg/dl. Chromoranin A was >500 ng/ml (referange range <94). Calcitonin, parathormon, anterior pituitary hormones and anti insulin antibody test were also in normal range. Abdominal computed tomography (CT) scan showed thickening in the pancreas (14 mm), and multiple hepatic metastatic lesions. Ga-68 DOTATATE PET/CT was performed, which showed positive lesions in liver, pancreas and peripancreatic lymh nodes and also left temporal cortex in brain. Brain CT showed a 15×11 cm nodular lesion in the left temporal lobe with contrast enhancement. The patient refused liver biopsy. The patient was diagnosed as malignant insulinoma.She was discharged on diazoxide 100 mg twice a day and prednisolone 4 mg/day to prevent hypoglycemia. On follow up, diazoxide was stopped due to volume retention and edema. Prednsiolone is stopped due to hyperglycemia and insulin glargine is started together with octreotide LAR 20 mg/month. Three months after the initiation of octreotide LAR injecitons the patient is doing well without hypoglycemia. Diagnosis of malignant insulinoma depends on the presence of metastases.The localization of insulinoma may be difficult.Ga-68 DOTATATE PET/CT is shown to be successfull in localizing insulinomas in clinical studies. The main treatment of insulinoma is surgery if possible. In the present case surgery was not possible due to patients diaspproval. Diazoxide and glucocorticoids are options to prevent hypoglycemia. Somatostatin analogues are effective in controlling hypoglycemia and also have antineoplastic and antiproliferative effects in malignant insulinomas. Insulinoma should be considered in the presence of atypical and recurrent hypoglycemia in patients with diabetes mellitus.