I think it’s to do with blood vessels abnormal response/exposure to cold weather, which results in these itchy swellings on toes and fingers. I haven’t been given treatment for it, other than keeping my hands and feet moisturised to prevent dryness and cracking. Which has helped for itchiness too. If it’s really bad, like open wounds or extreme itchiness, GP can prescribe something for it. But do stay warm, not too warm because that can aggravate the itchiness. Wear socks or slippers when you roll out of bed, make sure you wash or bath in warm water, not hot water and dry yourself properly, hats, scarves and ear muffs do help and wear thin layers of clothes to keep body heat in.
I don’t think it has anything to do with diabetes, unless your BG management is bad which can affect healing if your itchiness is bad to the point of bleeding/ open wounds. I was told exercise helps to keep blood circulation moving.