| In the US you can't be asked any medical questions until the employer makes a "conditional offer of employment". In other words they are saying that they have decided to hire you, but want a physical, drug screen, ect. This way if they turn you down after the conditional offer, they better be able to back the decision up, other than being scared of a diabetic. This rule is in place to protect the applicant in just these cases.
That doesn't keep the interviewer from describing the physical aspects of the job and asking if you are able to do it. It gives you the opportunity to establish that you are qualified for the job and keeps out any prejudices the employer might have about a medical condition until he makes an offer of employment. | 
