I guess it will depend on the company (dive op?) but if you are talking about recreational pleasure diving and not a class...I have never been required to present a medical form for any dives outside of class including Aruba, Bonaire, Grand Cayman, Cozumel, mainland Mexico...Well I'm going to be getting certified within a year for sure and this is a question for after being in a class and passing it. I'll be within that time frame for the class where I'll have an instructor.
My concern is when I go to the Caribbean in 2-3 years after and dive through a company, and they have me fill out that form and I put YES for having asthma. Can I show my old form or in that case will I need another one that is within a year of being signed?