Assuming there is no underlying medical reason for this, my first action, in your shoes, would be to increase my fluid intake a bit.
Here in the tropics, both myself and my (non-diabetic, super healthy) OH find if we are beginning to become dehydrated our ankles swell. I know it's counter-intuitive, but after a day or so, of increased fluids, we find it eases.
For the short while I tried the proper LCHF approach, I found my urine to be pretty concentrated. I don't know whether ones body needs additional fluid to deal with the adjusted, erm, "outputs" from that style of diet, or whether it just didn't really suit, me overall.