We can but it requires the patient to manage their blood sugar very, very carefully and a lot of them can't do it 100% of the time. Whenever they don't, the damage happens and it accrues. I see a guy in the 'hood who's had much of his foot amputated as a result of diabetes.
That's probably only because we can generally manage diabetes pretty well, though it does impose a lot of cost on society to do so.