I was diagnosed with IPN many years ago and the progression has been slow as to new areas, but faster as to degree of numbness in the original areas. That is still largely limited to my feet. I have a lot of stiffness (tightness?) throughout my body, particularly if I sit or lay down for long periods. I believe this is due to arthritis. This is lessened by getting outside and walking around the block. It is difficult to get started but the rewards are big. But then, the stiffness comes back as soon as I become inactive. I have been pre-diabetic for years. I, like you, go through periods where I eat a lot of sweets and am constantly trying to control this. However, my doctor told me that carbohydrates are a big contributor as well.