We report that (a) systemic blockade of the TLR4-MD2 complex lowers mean arterial pressure (MAP) in diabetic animals; that (b) type 1 diabetes modulates the levels of MD2 in the aorta, but not of TLR4, at least in the conditions evaluated in this study; and, that (c) acute inhibition of this receptor or its co-adaptor improves aortic vascular function by reducing vascular contractility and oxidative stress. This evidence concerns the gene TLR4 and type 1 diabetes mellitus.