BACKGROUND: The prevalence of diabetes mellitus (DM) in pregnancy is on the rise. Despite that gestational hypercoagulability is a physiological condition, diabetic pregnancy is associated with a high risk of venous thromboembolic complications (VTEC). There are many surveys related to the hemostatic parameters in non-pregnant women, but studies in pregnant women are not enough.AIMS: To assess the coagulation and vascular-platelet hemostasis parameters in pregnant women with various types of diabetes mellitus, taking into account its correction method. The data were compared with these indicators in women with preeclampsia and healthy pregnant women at the same gestational age.MATERIALS AND METHODS: An observational, single-center, retrospective cohort study was carried out at D.O. Ott Research Institute of Obstetrics, Gynecology, and Reproductive Medicine. The study included 1994 pregnant women who presented several groups taking into account the type of DM and its correction method, a group of women with preeclampsia (PE), and healthy women. The analysis of clinical data was carried out at 28–32 gestational weeks from 2012 to 2017. The study’s primary endpoint was taken as indicators of fibrinogen content, prothrombin index, thrombin time, activated partial thromboplastin time (APTT), and international normalized ratio (INR) antithrombin III, D-dimer, von Willebrand factor, and fibronectin. Additionally, the incidence of VTEC during pregnancy and within six weeks after delivery, gestational arterial hypertension, preeclampsia, fetal growth restriction, premature birth, and stillbirth cases was assessed.RESULTS: in pregnant women with various types of diabetes mellitus and preeclampsia, a state of pathological hypercoagulation was observed compared to the control group. These changes were characterized by an increase and activation of the following blood parameters: fibrinogen, the degree and rate of platelet aggregation, D-dimer, homocysteine, von Willebrand factor, and fibronectin. At the same time, the content of antithrombin III was significantly reduced in patients with DM. Correlation analysis established a direct relationship between the range of the studied factors with the degree of glycemic control and the frequency of obstetric complications.CONCLUSIONS: Diabetes mellitus in pregnancy is associated with a hypercoagulation condition and overexpression in the synthesis of endothelial dysfunction markers. Moreover, the severity of these processes depends on the type of DM and the severity of metabolic disorders. In diabetic pregnancy, exceptional attention to coagulation indicators, regular monitoring, and preventive treatment is required in order to improve the perinatal outcomes.