The study was conducted to find if there is a correlation between uterine arcuate artery Doppler and placental vascular pathology in patients with type Ι diabetes mellitus. Pulsed wave Doppler was used to sample the uterine arcuate artery beneath the placenta in 50 pregnant females at 37 weeks of gestation or more, 25 of them were normal and the other 25 had diabetes mellitus type Ι. A placental pathologist without knowledge of Doppler information, classified the histological appearance of the decidual arteries as normal, type A (hyalinization, mural thickening), type B (fibrinoid necrosis, atherosis, thrombosis). The study showed that females with normal or type A had similar S/D ratio, whereas those with type B had significantly higher S/D ratio.