The ruling on whether a sick person, such as one with diabetes or who requires regular medication, can fast is conditional upon their specific medical situation. The basis for this is the principle of ease in Islam and the explicit permission granted to the sick.

In its rulings, the Permanent Committee for Scholarly Research and Ifta' (al-Lajnah ad-Da'imah) clarifies that illness is a valid reason for not fasting in Ramadan. The committee differentiates between two types of illness:

1. Temporary Illness: If the illness is temporary and recovery is expected, the person is permitted to break their fast. However, they must make up for the missed days by fasting an equivalent number of days after Ramadan, once they are well.

2. Chronic Illness: If the illness is chronic, such as persistent diabetes, and there is no hope of recovery where fasting would be possible, the person is exempted from fasting altogether. This also applies to elderly individuals for whom fasting presents excessive hardship. Instead of making up the fasts, they are required to pay a 'fidyah' (expiation), which involves feeding one poor person for each day they miss. The amount is typically half a sa' of the local staple food, which is approximately 1.5 kilograms.

The critical factor in making this determination is the advice of a competent and trustworthy Muslim doctor. If the doctor confirms that fasting will harm the patient, worsen their condition, or delay their recovery, then it is permissible for them not to fast. This is particularly relevant for diabetics who may need to take insulin injections or pills during the day, as missing these doses could be life-threatening. If the medication can be safely adjusted to be taken only between sunset and dawn without harm, then the person must fast.

Therefore, the patient must consult a reliable physician. If fasting is deemed harmful, they are permitted to not fast and should offer the fidyah if the condition is chronic. If it is not harmful, they are obliged to fast.