With any medical condition, it is highly recommended to consult your physician before starting a diet or exercise program. Each FastBlast Smoothie contains a balanced mixture of carbohydrates, protein, fat and fiber—with no added sugar. Greatly reducing calories can cause a deviation in insulin, so caution is warranted for diabetics. It would be wise to start slower; perhaps just replacing one meal with a FastBlast Smoothie, then for two meals, and work up to a full day and then possibly two days. Again, please check with your physician because blood sugar must be monitored very closely especially, if you are on medication.