Prospects of using continuous glucose monitoring in patients with insulinoma

Abstract

The review is dedicated to the coverage and evaluation of insulinoma diagnostic methods, their interpretation and possibility of implementation in practice. Insulinoma is a neuroendocrine tumor that produces an excess amount of endogenous insulin, which leads to hypoglycemia, in particular, often unaware. Despite the fact that insulinomas are rare, they can cause serious metabolic disturbances requiring early diagnosis and treatment. Recent studies have shown that patients usually have fasting hypoglycemia, experience neurological symptoms such as confusion, visual disturbances, seizures, amnesia or abnormal behavior and autonomic symptoms such as palpitations, sweating or tremors. Currently, the diagnosis of hyperinsulinism can routinely be confirmed by a 72-hour fasting test. However, this test method creates certain inconveniences, such as the risk of older people having a low screening positive rate, prolonged hospital stays and fasting, resulting in patients often failing the test and not developing hypoglycemia. In turn, the role of continuous glucose monitoring (CGM) as a new method for detecting hypoglycemia is noted. The CGM technique, devoid of the disadvantage of multiple reinvasions, provides measurement of blood glucose concentration almost continuously for several days. CGM software can offer various metrics that reflect the fluctuations in blood glucose levels in particular, intraday glycemic variability (GV) parameters, including the coefficient of glucose variation (CGV). CGV not only reflects the signs of hypoglycemia, but also has a close relationship with the pathological characteristics of insulinoma, which is an important reference point for choosing surgical treatment and assessing prognosis. A correlation analysis has been found that confirms positively correlation of CGV with the insulin release index, C peptide in attack and the insulin level in attack, but negatively with the level of glycated hemoglobin (HbA1c).