the circumstances require him to do so and he cannot rescue the other person from destruction except by breaking his fast; in that case he may break the fast and must make up the missed day later.

Question: Is he also required to feed the poor as an expiation in addition to making up the fast?
Answer: Concerning the expiation, I cannot say anything with certainty; however, he is definitely obliged to make up the day he missed.
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Breaking the Fast for the Sick

Question: A man has suffered from diabetes for three years. He used to fast the month of Ramadan, but only with great difficulty. May he break the fast this year, and what is required of him if he does? The illness constantly leaves him hungry and thirsty even when the weather is moderate.

Answer: Fasting the month of Ramadan is one of the pillars of Islam. Allah the Exalted says, “O you who believe, fasting has been prescribed for you as it was prescribed for those before you so that you may become God-fearing” (al-Baqarah 2:183), and He also says, “So whoever of you witnesses the month, let him fast it” (al-Baqarah 2:185).

Thus the Muslim must fast unless he has a valid excuse; in that case, he may break the fast because of the shar‘i excuse and make up the missed days later. Those who are excused from fasting in Ramadan are the traveler and the sick person. Allah the Exalted says, “Whoever among you is ill or on a journey, then an equal number of other days” (al-Baqarah 2:184). Therefore, the sick person may break the fast and later make up the days he missed if that is possible. Since you are ill, you may break the fast if fasting is hard for you, or if fasting aggravates or intensifies the illness; in that situation, you should avail yourself of Allah’s concession.