The present study sought to examine the occurrence of subclinical markers of cardiovascular risk and cardiac dysfunction with increasing disease duration in type 1 diabetes mellitus (DM). There are few data on subclinical cardiovascular abnormalities in type 1 DM. The study included 100 patients without any cardiovascular complaints (mean age 46.6 years, range 22 to 63), with a history of type 1 DM ranging from 2 to 36 years, and 75 age-matched controls. Standard 2-dimensional and Doppler echocardiography and pulse-wave tissue Doppler (tD) mapping of systolic (Sm) and diastolic (Em, Am) velocities (12 left ventricular [LV] segments and right-sided cardiac) were performed. An Em/Am ratio of <1 was considered to represent abnormal segmental diastolic function. Flow-mediated dilation (FMD) of the brachial artery, carotid intima media thickness (IMT) measurement, and extensive laboratory analysis were performed. The FMD was reduced, and IMT increased in patients (p < 0.01). Regional tD-derived diastolic and systolic functional abnormalities were observed within the first decade of the disease. Significant correlations were found between FMD and LV segments with tD-derived dysfunction, the duration of DM, and fibrinogen (p < 0.0001 for all). Stepwise regression analysis showed that FMD was the strongest predictor of abnormal segmental function (p < 0.0001). Data further presented as an analysis of tertiles by DM duration show an increasing occurrence of subclinical cardiac dysfunction and cardiovascular risk markers compared with age-matched controls. In conclusion, FMD is associated with abnormal segmental cardiac function in type 1 DM.