This study compares NT proBNP and troponin T levels in umbilical cord arterial blood and postnatal echocardiographic findings for infants of gestational and pregestational diabetic mothers and macrosomic infants. Twenty-seven infants of pregestational diabetic mothers, 61 infants of gestational diabetic mothers and 37 macrosomic infants of nondiabetic mothers were prospectively enrolled in this study along with a control group of 58 healthy infants of mothers without any pregestational or gestational disorders as the control group. All enrollees were born after 34 weeks of gestation. For this study, umbilical cord blood was drawn during delivery to determine NT proBNP and troponin T levels. Echocardiography was performed 24-72 h after the delivery. Umbilical cord troponin T and NT proBNP levels were found to be higher in the diabetic and macrosomic groups than in the control group (all of them p < 0.001). NT proBNP levels were positively correlated with interventricular septum thickness in the pregestational and gestational infants of diabetic mothers groups (r = 0.564 and r = 0.560, respectively, p < 0.01). Both pregestational and gestational diabetic mothers were divided into two groups according to HbA1c levels in the third trimester as good (< 6.1 %) and suboptimal (> 6.1 %) metabolic control. In the good and suboptimal metabolic control diabetic groups, NT proBNP levels were also positively correlated with interventricular septum thickness (r = 0.536 and r = 0.576, respectively, p < 0.01). In the suboptimal metabolic control diabetic group, NT proBNP was only found to be positively correlated with the left ventricular mass index (r = 0.586, p < 0.01). While there was no correlation in the myocardial performance index between infants of diabetic mothers and the control group, the myocardial performance index of macrosomic infants was lower than that of the control group (p = 0.017). Cardiac biomarkers (NT proBNP and troponin T) were elevated in infants of diabetic mothers and macrosomic infants. While there was a positive correlation between NT proBNP levels and cardiac structure in infants of pregestational and gestational diabetic mothers, there was no relationship between NT proBNP levels and cardiac function.