Diabetic person should avoid fasting. It is important to note that in a human being all vital organs like heart, brain, kidney, lungs etc. are working constantly & they require energy to work. For the proper supply & utilization of energy, diabetics must take routine diet and medicines regularly.
If they don't take food and medicines on time, it may lead to major swings in blood sugar levels (low as well as high) and coma. There fore, fasting is not advisable.
But if it becomes unavoidable to observe fast, take tea/milk, fruits, buttermilk, etc. as per the advice of dietician. Moreover, take vegetables made of cucumber, tomato, carrot or bottle gourd; “Rajagra Bhakhri, Moraiya Khichdi, Sabudana Khichdi” equal to your usual food. Consult doctor regarding the medication and their dosages during this period.
In the month of Ramzan, Muslims are taking meal at night instead of day, so they can take morning dose of medication at night and night dose of medication at early morning.