"NHS versus private care"

I was booked in for a rotator cuff repair on my shoulder and went along to a pre-assessment five days beforehand. To my astonishment, I was contacted in the evening, the day before surgery only to be told that my operation was not going ahead as my blood sugar levels were 1.5 outside the safe level of 8.00. Blood pressure was 120 and BMI 25. Goring Hall said that there was an increased risk of infection due to new NHS guidelines produced two weeks ago so i needed to reduce my blood sugar levels first before any surgery. This begs the question; would they be this strict if I was paying GBP 3,500/4,000 for a shoulder op' or is it because the NHS is unwilling or incapable of paying for this simple surgery unless all boxes are ticked and thus eliminate the risk of litigation? The risk of infection is so small and relative to any other open surgery.