Question: Allaah (Glorified be He) willed that I have been suffering from diabetes since I was about 14 years old and in 17 Muharram, 1411 A.H., I had kidney failure; and in 16 Jumaada Al-Thaanee, 1412 A.H., I had a kidney transplant in the Arab Republic of Egypt, which cost me a large sum of money. When Ramadaan, 1412 A.H. started, the doctor ordered me not to fast, so I fed one Miskeen (needy) for each day. And, I have a follow-up in hospital every month and a half, so I asked the doctor about Sawm, and he told me to fast if I can, and not to fast if I am not able to, knowing that the doctor is a Muslim, and he is Sudanese.
Knowing, respected Shaykh, that the doctor told me that: If you fast, do not do a lot of work and do not sleep at night so as to make up for the liquids that you lost throughout the day. In addition, I take medicine for diabetes in the morning and in the evening, and another medicine between 9:00 am and 10:00 am, and between 9:00 pm and 10:00 pm. The doctor has also advised me to drink 4 or at least 3 bottles of mineral water a day. Knowing that I argued with the doctor about Sawm and he did not tell me whether to fast or not, I ask Allaah (Exalted be He), then Your Eminence, to answer my question and tell me whether I can fast or not. May Allaah reward you with the best.
Answer: You must fast if delaying the medicine till night will not cause you any harm, but if you find it difficult to fast or your illness worsens, or if taking the medicine is necessary during the day in which you have to fast, you do not have to fast and you must feed one Miskeen for each day. This should be one and a half kilos of the country’s staple food, if you are not likely to recover and are not able to compensate for the days that you missed… read more here.