I have a problem with diabetes, type 2, and the doctor that manages my diabetes advised me to walk more, purchase corrective fit hiking/walking footwear and good quality socks with cushioning. I do not have neuropathy in my lower legs or feet yet but the longer I can delay it the better. The walking shoes she recommended suit me perfectly and she recommended Darn Tough cushioned merino wool socks for additional support.
I am a size 12 shoe and have always purchase those multi pack 6 to size 12 shoe size synthetic fiber socks, so they stretch to the maximum on me and are always uncomfortable when wearing a long time. I would often get a rash and itch on my lower shin and around my ankle and just assumed it was to do with my diabetes. The difference in comfort wearing a sock for my shoe size compared to the multi pack sock is incredible, the cushioning really helps on long walks, but the other main difference is I never get a rash around my ankle or lower shin. For me the relief from skin rashes and comfort of these socks on my feet is worth the high initial cost.
I have just ordered another eight pairs so I will have about 30 pairs of Darn Tough Merino wool socks. I have only been wearing them for a couple of years and so far none have needed replacing so I can not comment on the warranty. My wife washes them inside out inside a laundry bag in cool water with a wool detergent and hangs them to dry. The only problem so far is some pilling of fiber on the surface but most of it is on the inside of the sock and on the outside around the heel.
My wife is now buying Merino Wool socks but she has tried different brands and not just Darn Tough, she likes all of them.