Objectives: The aim of the study is to compare the fear of hypoglycemia in patients with diabetes mellitus type 1 on self-monitoring of blood glucose (SMBG) and flash glucose monitoring (FGM). Different attitudes during episodes of hypoglycemia, both from an aspect perspective of behavior and worry, were investigated. Materials and methods: This prospective observational study was carried out among patients with diabetes mellitus type 1 controlled at the University Hospital of Split. The questionnaires were conducted by phone from May to June 2020. The participation was anonymous and voluntary. 80 patients, 44 females and 36 males on SMBG were included. We also included 77 patients using FGM FreeStyle Libre sensor, 44 females and 33 males. Results: We found no statistical significant difference in total number of patients using SMBG and FGM (P=0.810) nor between males and females (P=0.787). Patients using FGM are on average 5 years older and have 4 years less disease duration than the patients using SMBG, but this is not statistically significant (P=0.385) and (P=0.094). We found a statistical significant difference in behavior between patients on SMBG and FGM (P<0.001), but we did not find statistical significant difference in level of behavior between males and females according to which type of glucose monitoring system they use (P=0.549) and (P=0.093). Correlation between behavior and duration of disease is negative, but significant (P=0.038). We found no statistical significant difference in worry for patients on SMBG and FGM (P=0.664). When we compared worry related to the type of glucose monitoring system used (P=0.430), and gender (P=0.098), we could not find a statistical significant difference. Females using FGM reported the highest incidence of worry, while males using FGM have the lowest values. We found a statistical significant difference between the groups (P=0.010). In this study we were not able to find a correlation between worry and the duration of the disease, there is no statistical significant difference (P=0.203). Conclusion: The fear of hypoglycemia, from an aspect of behavior, is bigger in the patients using FGM than for the ones using SMBG. However, from a perspective of worry, the fear of hypoglycemia is smaller in the patients using FGM than for the ones using SMBG. There is a smaller difference between males and females using FGM than the ones using SMBG, when considering the behavioral part about the fear of hypoglycemia. From a perspective of worry, there is a bigger difference between males and females using FGM than for the ones using SMBG. The fear of hypoglycemia, when considering behavior, is smaller for patient having diabetes mellitus type 1 for a longer period of time. We were not able to detect any correlation between worry and the duration of the disease in this study.