Introduction: Diabetes mellitus is associated with long-term damage, dysfunction and failure of various organs especially the eyes, kidneys, heart and blood vessels. Abnormalities of LV function primarily reflected a diastolic abnormality which was an early sign of diabetic cardiomyopathy and had been shown to precede systolic dysfunction in diabetic patients. Echocardiography can be used for the diagnosis of diabetic cardiomyopathy or diabetesinduced myocardial dysfunction. Moreover, tissue Doppler Imaging (TDI) had emerged as a new sensitive technique for the evaluation of diastolic function. Aim of the work was to detect early left ventricular dysfunctions in children with type 1 diabetes mellitus and their correlation with the glycemic control of these children. Subjects and methods: This study included two groups, (Group Ι) included 46 children who were diagnosed as type 1 diabetic patients, and (Group II) which included 23 apparently healthy, age and sex matched children as a control group. They were subjected to thorough history taking, clinical examination, laboratory investigations including total serum cholesterol and triglycerides. Left ventricular functions were assessed by resting Trans Thoracic Echocardiography (TTE) and Tissue Doppler Imaging (TDI). Results: There were significant higher diastolic indices by both TTE and TDI in type 1 diabetic children than the control group. Diagnosis of definite left ventricular diastolic dysfunction was detected in 5 (10.9%) diabetic children by TTE and in 7 (15%) diabetic children by TDI. Finally, there were insignificant associations between duration of the disease, hypoglycemic attacks, DKA, systolic and diastolic blood pressures, HbA1c% levels and different echocardiographic, tissue Doppler parameters. Conclusion: Alteration of myocardial function induced by DM may begin earlier than was generally thought and these changes might be not correlated with duration of diabetes nor glycemic control. Children and adolescents with T1DM already have significant changes in myocardial diastolic function of the LV and seem to be at risk of developing further cardiac dysfunctions.