Hawzah News Agency – Q: Diabetics are required to take insulin injections once or twice a day. Also, their meals should not be delayed or taken at long intervals; otherwise they might go into a coma or get fits. That is why physicians advise them to have four meals a day. Please give your opinion concerning their fasting.
A: If abstaining from eating and drinking from dawn to sunset is harmful to their health, fasting is not obligatory for them. In fact, it is not permissible for them to fast.
Source: https://www.leader.ir/en/book/32/Practical-Laws-of-Islam