If "absolute" is taken to mean "unconditioned" then from a Kantian perspective there is some thing, called "noumenon", which corresponds to what is unconditioned in any experience.
However I'm not so sure it would constitute an "absolute truths", because "truth" only relates to propositions. If "absolute truth" is taken as that which is true in any possible situation, then I can't see how any such proposition would be possible. All the content of the Critique of Pure Reason, for example, relates only to human reason. To divine reason, all things would appear certainly and completely determined, such that the proposition "there is 'noumenon'" would be false.
I also don't think that "there is a reality" is absolutely true because, while it's true for both human and divine reason, it would be indeterminate for some empty "experience", like that of a dreamless sleep. All which is "absolute" in Kant is only so with reference to the conditions of human experience, which is non-empty. But if nothing is conceivable, then the existence of that which ought to underlie the determination of anything (the whole of reality, "omnitudo realitas", the stuff of Kant and Hegel) is in itself indeterminate.
On the other hand, the only argument ever conceived that claimed to prove things without reference to any experience is the ontological argument, and there is no agreement as to whether it "proves" anything. Everyone thinks there's something cheesy about it, but no one can really tell what. But if you do believe in it, then I guess "'being' is" would be an absolutely true proposition and that "non-being" is impossible, and I should turn my mind away from it.
So I don't think there are "absolutely true" propositions, specially not concerning things-in-general. There might be some regarding experience, such as "there is a reality", but these are only true for human reason, which nonetheless can never attain any other absolute truth beyond such vague notions as we can only perceive what is conditioned.