Does Exhaust reduce true damage?

I was playing Garen, and was recently placed in a situation where I was exhausted while diving the villain. Garen get's 1% max Hp true damage per tick on his spin vs. the villain and true damage on his ult. I'm curious whether the true damage was reduced at all, because I know that true damage gets fully applied vs Garen when he activates his w (which reduces all incoming damage by 30%), but the verbage is slightly different on Exhaust (reducing... their damage dealt by 40%).

Thanks in advance