Background: Diabetes mellitus type 1 (DM1) is frequently accompanied by increasing risks of cardiovascular diseases. The prevention of cardiac complications depends on the early diagnosis of myocardial dysfunction. Objective: Our objective was to assess both right and left ventricular (LV) functioning in DM1 patients depending on strain imaging by 2D-speckle tracking echocardiography (2D-STE). Patients and methods: The present prospective, case-controlled study was conducted in the Cardiology Department, Menoufia Faculty of Medicine, from May 2021 to December 2022. 90 subjects were selected, divided into two groups. 60 patients with type I diabetes mellitus served as cases and 30 healthy subjects age matched served as control. Results: E wave, E/A value, GLS endo, GLS myo and average global longitudinal strain were lower in patients than controls (70.43± 13.67 cm/s vs. 84.67 ± 11.97 cm/s, 1.05 ±.25 vs 1.4 ± 0.18, –20.48 ± 2.81% vs. –24.08 ± 1.11% , –18.71 ± 2.09 % vs. –21.76 ± 1.01 %, and -18.82 ±1.92 % vs 21.1± .62 % respectively, p < 0.001), meanwhile there was no difference between both groups regarding ejection fraction and RV strain measurements (68.48 ± 5.96 % vs. 67.39 ± 3.55% and –21.13 ± 1.29 % vs. –21.06 ± 1.24 % respectively, p =0.357 and p =0.807). Conclusion: Patients with DM1 and without known heart diseases have diastolic and subclinical systolic dysfunction with lower LV endocardial and myocardial longitudinal strain demonstrated by multi-layered STE.