Can a Muslim pay the fidyah (compensation) for the days that he did not fast, even if he was healthy, because he is suffering from diabetes and high blood pressure? Can he feed a poor person once or twice? He works overseas and has come to his own country for a month-long vacation.

Praise
be to Allah

Patients who have diabetes and high blood pressure are not
all the same. Rather doctors divide them into various categories. Some of
them are able to fast safely, if they adhere to medical guidelines, and
others cannot fast. 

But if diabetes and high blood pressure occur together, then
fasting is more difficult for the patient. 

Based on that, the patient should consult his doctor and do
whatever the doctor advises with regard to fasting or not fasting. Not every
person who is sick is permitted to break the fast, as has been explained in
fatwa no. 1319. 

Secondly: 

As diabetes and high blood pressure are chronic diseases, in
most cases the patient who does not fast because of them will never be able
to make up those fasts. Therefore what he must do is feed one poor person
for each day that he does not fast, and he does not have to make up the
fasts. 

What is meant by feeding a poor person is giving him one
meal, and the patient has the choice between making food and inviting the
poor person to come and eat, or giving it to him, cooked or raw. If he does
one of these three options, then he has fed a poor person and has done what
is required of him, as has been explained in fatwas no.
49944 and 101100. 

And Allah knows best.