I understand your frustration smokey. I spent a year trying and failing to recover from a bad PKR, and battling with my weight as I became more and more sedentary. Although not diabetic, I am obese and prior to knee problems had become very active over a few years, did traditional low fat diet and managed to lose 7 stone, then menopause and knee pain hit me and I put half stone back on. Desperate not to put all the weight back on I had worked so hard to lose I started to research in a big way how to change my eating lifestyle permanently. Then op number 1. (All health advisers say dont fast or restrict post op - so over 3 months I gained another half stone. Then started low carb and intermittent fasting which halted weight gain). Now at 2nd op recovery and naturally eating lowish carb diet, but not calorie restricting. Will start intermittent fasting properly again around week 8, and calorie restrict from week 12 (going on cruise week 18 so need to lose some weight before then!).
Keep posting, I will be praying that your op can go ahead as planned.