You have one of the best motivations of anyone on here. Diabetes is a complex disease, but it can't be manageable and not cause serious injury if handled right. It is wise of them to only push for a 15% weight loss. For most people, any more than that would just freak people out and overwhelm them. You can do it, but just use the tools they give you for balancing your fast carbs, slow carbs, protein and fat. Drink lots of water! Once you pass that 15% goal they set for you, you will be well on your way. Good luck!