Hypoglycemic syndrome is a symptom complex that results from low blood sugar levels. In the endocrinologist practice, an insulinoma that is a small tumor in the pancreas that produces an excess amount of insulin is regarded as the main cause of hypoglycemia in patients without diabetes mellitus. Various molecular and genetic disorders develop in the insulinoma tissue, that lead to a change in the secretion of insulin and its precursors.There is often a situation when it is not possible to establish the cause of lowering blood glucose levels. In such cases, the development of hypoglycemia can result from various genetically determined enzyme, autoimmune and receptor disorders that cause a change in glucose metabolism or the synthesis/bioactivity of insulin. In the mild course of such congenital diseases, hypoglycemic conditions may first manifest in adulthood.The review describes various genetic predictors (mutations) that play a decisive role in the development of enzyme, autoimmune, receptor and proliferative disorders and, as a consequence, hypoglycemia.