Diet and exercise can help to lower and control sugar levels
and high blood
pressure, but this does not mean
that he can stop taking his medications. His doctor is the best person to advise him because his doctor will be monitoring his sugar levels and blood pressure on a regularly basis, if not, then he should be (about once a year if everything is stable).
With diabetes, it also depends which type he has. Type 2 diabetes can be controlled by diet and exercise, but not always.