Objective: To analyze glucose variability and investigate its role as a predictor for preeclampsia development in pregnant women with type 1 diabetes mellitus (T1DM) with various insulin therapy regimens. Methods: A total of 200 pregnant women with T1DM were included in the study. A hundred women used continuous subcutaneous insulin infusion (CSII), and the rest of the group was administered with multiple daily insulin injections (MDI). Continuous glucose monitoring (CGM), index calculation of glucose variability (MAGE, MODD, CONGA, and CV), assessment of preeclampsia frequency and severity were conducted. Results: The work results show the link between the severity rate of preeclampsia and the duration of T1DM as well as the level of HbA1c before and during pregnancy. The rate of preeclampsia in the group of women, using CSII comprises 26.8% of cases that appear less than in the group of those, administered with MDI that is 46.6% (χ 2 = 5.45; р 1.07 and CONGA > 3.39. Conclusion: Comprehensive evaluation of the glycemic profile while using CGM revealed a correlation between pathological glucose variability and the frequency and severity of preeclampsia thus proving the benefits of CSII in pregnant patients with T1DM to perform glycemic targets and decrease glucose variability, which eventually led to the decrease of preeclampsia frequency in this group of women.