Insulinomas are the most common functioning pancreatic neuroendocrine neoplasms (pNENs), developed mainly from pancreatic islet cells. More than 90 % of insulinomas are sporadic, benign and small sized. Autonomous production of insulin results in neuroglycopenic and adrenergic symptomatology with potential lethality. Surgery remains the only curative treatment with a high success rate. Preoperative tumor localization is challenging, but important for appropriate surgical approach. Metastatic forms represent a challenge, mainly on the field of therapy, with the need of tumor burden reduction and glycemia stabilization. The rarity of malignant forms limits reports on therapeutic strategies and outcome.Authors present in this article a summarized overview of epidemiology, clinic, diagnostics and treatment of benign and malign forms of insulinomas. Key words: insulinoma, neuroendocrine tumors, hypoglycemiaInsulinomas are the most common functioning endocrine neoplasms of the pancreas and represent 1 -2 % of all pancreatic neoplasms [1]. They are developed from pancreatic beta cells and the autonomous production of insulin is one of the most common causes of hypoglycemia by non-diabetic patients. Beside the production of insulin, production of even other hormones like gastrin, glucagon, somatostatin, serotonin, adrenocorticotropic and human choriogonadotropic hormone can be present [2]. Estimated incidence is 1 -4 people per million [3]. Insulinomas can occur at any age, but there is an age-specific incidence peak in the fifth decade of life in general population and in the second decade by patients with multiple endocrine neoplasms type 1 (MEN 1) [4 -5]. Slightly higher incidence by women than by men is observed (60 : 40 %).[2] Most of the insulinomas are located in the pancreas with equally distribution over its parts. Extrapancreatic occurrence of the primary lesion is extremely rare (incidence < 1 %) and the most frequent locations are duodenum, ileum, lungs, ovary and cervix [1,6]. 90 % of insulinomas are benign, sporadic, solitary and smaller than 2 cm. Less than 10 % are malignant, with metastatic distribution into lymphatic nodes, liver, bones and peritoneum [7 -9]. Approximately 5 -10 % of insulinomas are part of hereditary disorders like MEN 1, von Hippel-Lindau syndrome, tuberous sclerosis or neurofibromatosis type 1 and often prone to be multifocal [4,10].Given by the dominant benign nature of these neoplasms, the curability after surgery is more than 95 %. Recurrence is seen in 7 % of the patients without MEN 1 at 20 years after surgery and in 21 % at 20 years by patients with MEN 1. Median disease-free survival interval by malignant insulinomas after curative resection of 5 years has been demonstrated, but with recurrence of 63 % at a median interval of 2,5 -3 years. Palliative resection is associated with a median survival of 4 years, compared with 11 month after biopsy only [11,12]. HistopathologyMajority of these neuroendocrine neoplasms appear well demarcated, but lack a well defined capsule and hav...