It is not advisable to fast for those diabetic. As it is, with all care, it becomes difficult to maintain sugar levels daily in spite of taking calculated food and of course with medicines - whether it is with tablets or insulin. In daily routine, if one takes bitter gourd/karela plus cucumbar/kheera plus tomato juice, diabetes can be controlled. Besides this, there are many natural and ayurvedic medicines are available for this problem. Take care of health and you will be fit to do normal duties without depending on others. Jai Hind. Jai Bharat.