Introduction. Rare types of diabetes mellitus including MODY (Maturity-Onset Diabetes of the Young) are quite complicated to verification and differential diagnosis. That is often leads to diagnostic delays, medical errors in choosing treatment tactics. This kind of event could aggravate the course of the disease and must be prevented.Aim. Evaluation the characteristics of glucose variability (GV) in different types of diabetes mellitus (DM) in young people using continuous glucose monitoring (CGM) systems is necessary to understand the diagnostic value of the method.Materials and methods. We studied 72 patients with clinical signs of MODY who underwent a molecular genetics study to verify the type of DM. According to the results of the study, patients were divided into 3 groups: with genetically confirmed MODY2 (n = 31), MODY3 (n = 16); comparison group consists of the patients with type 2 diabetes (n = 25). All patients at the second stage underwent CGM for 14 days. At the third stage, the obtained patterns of glycemia were presented in the form of GV indices using the GLINVA program, and an in-depth analysis of glucose variability was performed.Results. Some features in the characteristics of the glycemic profile in young people with monogenic forms of DM were noticed. It was determined that in MODY2 the level of fasting plasma glucose (FPG) (p = 0.004) and HbA1c (p = 0.010) was significantly lower than in MODY3, and low GV was determined during the day, which probably causes a lower incidence of diabetic complications than other types of diabetes. In individuals with MODY3, higher FPG and HbA1c values were found, in contrast to MODY2 and type 2 diabetes. MODY3 profile is characterized with significantly higher GV and longer time spent above the target ranges (compared to type 2 diabetes).Conclusions. The approach to evaluate the glycemic profile used in the study is modern and affordable. It could become a tool for determining criteria for diagnosing the type of diabetes in patients with clinical manifestations of MODY.