Insulinomatosis: new aspects

Endogenous hyperinsulinemic hypoglycemia (EHH) is a rare condition with an incidence of approximately 4-6 per million person-years and comprises a group of disorders causing hyperinsulinemic hypoglycemia without exogenous administration of insulin or its secretagogues. In adults, most cases (approximately 90%) are secondary to a single insulinoma. Other causes include insulinoma in the context of multiple endocrine neoplasia type 1 (approximately 5% of cases) and non-insulinoma pancreatogenous hypoglycemia syndrome, which is estimated to account for 0.5-5% of all cases. Recently, an entity called insulinomatosis has been described as a novel cause of EHH in adults. The characteristic feature of insulinomatosis is the synchronous or metachronous occurrence of multiple pancreatic neuroendocrine tumors expressing exclusively insulin. While most cases arise sporadically, there is recent evidence that autosomal dominant inheritance of mutations in the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog A (MAFA) gene can cause a familial form of insulinomatosis. In these families, EHH is paradoxically associated with the occurrence of diabetes mellitus within the same family. This review summarizes the current clinical, biochemical, imaging and genetic knowledge of this disease.

Case report: A particularly rare case of endogenous hyperinsulinemic hypoglycemia complicated with pregnancy treated with short-acting somatostatin analog injections

Hyperinsulinemic hypoglycemia is a rare disease, and only two cases complicated with pregnancy were published previously when our patient became pregnant. We introduce a successful management of a pregnancy in a patient with endogenous hyperinsulinemic hypoglycemia, a condition also known as non-insulinoma pancreatogenous hypoglycemia syndrome or formerly as nesidioblastosis. A 29-year-old female patient was treated with endogenous hyperinsulinemic hypoglycemia since the age of 4 months, taking daily 3 × 75 mg diazoxide, which adds up to 225 mg per day. Adequate glycemic control could be achieved with this therapy. Genetic testing and various imaging examinations were carried out earlier to specify the disease and to exclude focal forms. The patient came to the clinic with a positive pregnancy test and consequential hypoglycemic episodes. Hospital admission was needed to correct the metabolic condition. Although the patient was informed about the potential risks, she decided to carry out the pregnancy. According to the quite limited literature, somatostatin analogs are the only therapy used previously during pregnancy in hyperinsulinemic hypoglycemic patients. One publication reported normal pregnancy outcomes, but in another case, restricted fetal growth was observed. In our case, we stopped diazoxide and parallelly introduced short-acting somatostatin analog octreotide in the therapy, and further dietetic changes were proposed. In addition to daily regular self-blood glucose monitoring, regular gynecological controls were carried out monthly, and healthy fetal development was confirmed. The patient gave birth to her first child, a well-developed female neonate, in the 38th week, by a cesarean section.

Innovative imaging of insulinoma: the end of sampling? A review

Receptors for the incretin glucagon-like peptide-1 (GLP-1R) have been found overexpressed in selected types of human tumors and may, therefore, play an increasingly important role in endocrine gastrointestinal tumor management. In particular, virtually all benign insulinomas express GLP-1R in high density. Targeting GLP-1R with indium-111, technetium-99m or gallium-68-labeled exendin-4 offers a new approach that permits the successful localization of small benign insulinomas. It is likely that this new non-invasive technique has the potential to replace the invasive localization of insulinomas by selective arterial stimulation and venous sampling. In contrast to benign insulinomas, malignant insulin-secreting neuroendocrine tumors express GLP-1R in only one-third of the cases, while they more often express the somatostatin subtype 2 receptors. Importantly, one of the two receptors appears to be always overexpressed. In special cases of endogenous hyperinsulinemic hypoglycemia (EHH), that is, in the context of MEN-1 or adult nesidioblastosis GLP-1R imaging is useful whereas in postprandial hypoglycemia in the context of bariatric surgery, GLP-1R imaging is probably not helpful. This review focuses on the potential use of GLP-1R imaging in the differential diagnosis of EHH.