Can medical leaves be deducted as annual leaves?

Can medical leaves be deducted as Annual Leaves?
Generally, medical leave is approved based on valid medical chit issued by the company's doctor, or by a government doctor. Employee is eligible for medical leave if he has served the employer for at least 3 months and informed or attempted to inform the employer of his/her absence within 48 hours.
Unless employee falls sick on his applied annual leave, his absence from work would still be treated as annual leave and not sick leave. It is depends on company policy whether his employer may cancel his annual leave and as a concession, allow him to take sick leave instead.