The relevance of investigating carbohydrate metabolism (CM) in patients with acromegaly and Itsenko-Cushing disease is attributable to frequent glucose metabolic disturbances, on the one hand, and to difficulties in choosing sugar-lowering therapy in these categories of patients, on the other. The efficiency of hyperglycemia treatment in these patients may be reduced due to problems in achieving remission/cure of the underlying disease and to specific therapy favoring hyperglycemia. The top-priority tasks are to search for ways of reducing the frequency of CM abnormalities in patients with neuroendocrine diseases and to elaborate sugar-lowering therapy regimens. There is a growing interest in studies of the role of the incretin system in the pathogenesis of secondary hyperglycemias associated with neuroendocrine diseases. Nevertheless, few works have been published on this subject matter because of its novelty. There is a need for a further closer study of the specific features of incretin system function and the pharmacodynamics of incretin mimetics that are potential candidates as first-line drugs to treat secondary hyperglycemias. This paper attempts to summarize the available data obtained from studies into CM in neuroendocrine diseases.