Hi Michelle i dont really know either, but if your lungs can improve from giving up smoking i dont see why there wouldn't  be an improvement from being sugar free. 

I have been sugar free for four months now.I have lost 12kg, so far and have Fatty Liver disease. Just last week I went back to the Doctor to get my results back from my blood test (specifically for Fatty Liver). I am delighted to say that one of my readings is now in the normal range and the other shows improvement ! Doctor was surprised and asked what I was doing. He agreed that sugar was not needed and told me to keep up the good work.
My Brother-in-law is the one who enlightened me. He had been diagnosed with diabetes, and over 2 years, lost 30kg and is now no longer diabetic !