AIM: The aim of this study was to compare placental morphological features from women with different types of diabetes mellitus considering method of DM correction. MATERIALS AND METHODS: A retrospective, single-center, cohort study was carried out. We analyzed morphological examination results of 3300 placentas, which made up the following comparison groups: Type 1 diabetes mellitus on continuous subcutaneous insulin infusion (n = 60), type 1 diabetes mellitus on multiple subcutaneous insulin injections (n = 446), type 2 diabetes mellitus on diet (n = 95), type 2 diabetes mellitus on insulin therapy (n = 134), gestational diabetes mellitus on diet (n = 1652), gestational diabetes mellitus on insulin therapy (n = 735), preeclampsia (n = 39), and the control group (n = 139). The examined placentas were weighed, with their sizes (two diameters and thickness), cotyledon structure and defects assessed. We determined the umbilical cord junction and external characteristics of extraembryonic membranes. Fragments of the placenta (5 pieces) were fixed in 10% neutral buffered formalin (pH 7.2), processed with the Leica TP1020 tissue processor and embedded in paraffin. Histological sections (3-4 μm thick) were prepared and stained with hematoxylineosin. Statistical analysis was performed using the SPSS 23.0 and GraphPad Prism 8.0 software. RESULTS: Following characteristics were typical for all types of diabetes mellitus: Increased placental mass metrics, chronic placental insufficiency, dissociated villous maturation disorder with prevalent immaturity, as well as involutive-dystrophic and circulatory disorders of varying severity. Placentas from women with type 1 diabetes mellitus had the specific sings: The predominance of intermediate immature villi and stem villi stromal fibrosis. The frequency of placental infarcts and fibrinoid content in the intervillous space were comparable to those in placentas from women with type 2 diabetes mellitus. Inflammatory changes and moderate placental calcification were most consistently associated with type 2 diabetes mellitus, while gestational diabetes mellitus was characterized by "soft" damages. Placentas with preeclampsia showed higher prevalence of premature villous maturation, compensated placental insufficiency, and fibrinoid depositions in the intervillous and subchorionic spaces. CONCLUSIONS: Understanding relationships between placental histological features and clinical aspects of diabetes mellitus makes it possible not only to clarify the pathophysiological processes occurring in this pathology but also to optimize the algorithm for the rational management of the neonatal period of children from mothers with diabetes mellitus.