Don't know if anyone has mentioned it on here, but for walking - especially hiking - I only ever walk in 1000 Mile socks, not just since being diagnosed T2, but for the past 15 years or so. They're twin wall socks 'guaranteed not to give blisters for a thosand miles', hence the name. I've bought mine on eBay, from Go Outdoors & Cotswold Outdoors
They're about a tenner a pair (so not cheap). If I'm walking all day, I take a spare pair and swap them at lunchtime, preferably somewhere I can cool my feet in a nice slow brook or stream
I've tried most makes of socks, but 1000 Mile is, for me, the best. Must have over a dozen pairs now. Available in mens & ladies