What is the ruling on the possibility of switching to feeding (the poor) instead of fasting two consecutive months as expiation for a husband's intercourse with his wife during the daytime in Ramadan, due to diabetes and the severe fatigue that may occur during fasting?

You have committed a great sin by having intercourse with your wife during the day in Ramadan. You must repent to Allah and pay the expiation for intercourse during the day in Ramadan. If you are unable to fast, then feed sixty poor people. A strong presumption of inability to fast is sufficient for this. You may switch to feeding if you are among those permitted to break their fast due to illness.