I find that hot water makes my small fiber neuropathy burn horribly all night. But I discovered by chance that if I then run them under cold water for five minutes straight afterwards - soaking hands and feet - I get several hours of relief.

I think it's because it reboots the small fibers in a similar way to closing down a computer and then turning it back on. I'm not a scientist but this is how it seems to me. However mine is caused by autoimmunity rather than Diabetes and I also have some Raynauds as part of this - so with me it is about the vasodilation I'm pretty sure.