You should ask your doc abt this, not this general forum, cialis can affect heart function or ppl with high blood pressure.
Ppl with diabetes are prone to circulation problem when the disease progress to an uncontrolled level usually.. is your HbA1c ok?
One of the symptoms associated with progressing diabetes is erection problem.
Perhaps you might want to try R-alpha lipoic acid which is known to help ppl with diabetes for a better blood sugar management/prevent neuropathies, which theoretically and eventually would naturally help you gain back [the natural way] many bodily organ functions (although it may not be as when one is young, as male testosterone goes lower as they grow older)