Maternal diabetes mellitus (DM) is a chronic disease that carries significant risks for the fetus and newborn. Hyperglycemia during pregnancy contributes to the development of structural heart defects, myocardial hypertrophy, and impaired cardiac function in newborns. The objective of the study was to evaluate the echocardiographic parameters of the cardiac function in children born to mothers with type 1 diabetes mellitus (DM1).A prospective study of 163 newborns was conducted on the basis of the Republican Scientific and Practical Center “Mother and Child”. The children were divided into 2 groups. The main group consisted of 107 children born to mothers with DM1 (Gr1), the control group – 56 healthy infants born to women with normoglycemia during pregnancy (Gr2).It was found that a newborn in Gr1 has a larger thickness of the interventricular septum (IVS) (p < 0.001), the posterior wall of the left ventricle (p < 0.001), and the size of the right ventricle (p < 0.001). It was revealed that in Gr1 the frequency of myocardial hypertrophy with an interventricular septum thickness of 5 mm or more is 30.8 %, which is statistically significantly higher in comparison with Gr2 (1.8 %, F = 0.115, p < 0.001). When assessing the blood flow using a pulse-wave Doppler study, the manifestations of the diastolic dysfunction in Gr1 were revealed. The E/A ratio for the flow through the mitral valve in Gr1 was 0.9 (0.8–1.1), in Gr2 – 1.2 (1.0–1.4), p = 0.043. The study confirmed a lower frequency of registration of myocardial hypertrophy with good glycemic control during pregnancy (p < 0.05). Direct correlations between the average level of glycated hemoglobin in mothers and the IVS thickness (r = 0.374, p < 0.05) and the posterior wall of the left ventricle (r = 0.293, p < 0.05) of their newborns were observed in infants in Gr1.The use of pump insulin therapy in pregnant women with type 1 diabetes allowed a statistically significant reduction in the frequency of hypertrophy of the left ventricle in infants in the neonatal period.Diabetes mellitus type 1 in the mother determines not only the risk of congenital heart defects, but also hypertrophic changes in the myocardium, contributes to the diastolic dysfunction in this group of children. The achievement of target levels of glycated hemoglobin during pregnancy, using pump insulin therapy, provides a lower frequency of registration of ventricular septal hypertrophy. The revealed statistically significant differences in the IVS thickness and the posterior wall of the left ventricle in infants born to mothers with type 1 diabetes should be taken into account by doctors in the system of organizing medical care in inpatient settings and at the stage of dispensary observation.