Objective: Contraction and relaxation of the heart cause decrease and increase in myocardial video intensity (MVI) recorded from echocardiographic images, respectively. The present study was planned to compare this physiological cyclic variations of MVI in patients with type I diabetes mellitus and healthy subjects. Methods: For this purpose, standard echocardiographic examination was performed to 18 young patients (age 23.2±6.4; range: 15-37 years) with insulin dependent type I diabetes mellitus (diabetes duration: 7.8±5.6; range: 1-17 years) and 14 age and sex matched controls. In all subjects, end-diastolic end end-systolic *D echocardiographic images of 3 consecutivite beats that had been recorded on videotapes were digitized. The quantitative analysis of the digitized imaging was performed with the help of a calibrated digitization system in order to calculate the septum and the posterior wall textural parameters. The cyclic variation index (CVI) of the mean gray level (MGL) was calculated according the formula: (MGL diast-MGL syst)/MGL diast x 100. Results: Among the groups, left ventricular diastolic dimension-index, fractional shortening, E/A ratio, and isovolumic relaxation time showed no statistically significant differences, while septum (8.3±1.1 vs. 7.3±0.9 mm; p=0.016) and posterior wall thickness (8±0.6 vs. 6.8±1.1mm; p=0.004) and E,deceleration time (167±23 vs. 140±19 msec.; p=0.003) were significantly higher in diabetics. The diabetic patients showed significantly lower CVI both for septum (18.2±11.5 % vs. 39.3±11.5 %; p=0.0001) and posterior wall (16.4±16% vs. 40.5±9.2%; p=0.0001), respectively. Conclusions: Altered videodensitometric parameters possibly represent a preclinical alteration, conceivably related to the myocardial collagen content increase, which does not necessarily indicate an actual disease but may be cansidered an early marker of the histopathologic findings of diabetic cardiomyopathy.