I Am A 56 Yr Old Male And Have Been

I am a 56 yr old male and have been diagnosed since 2012 with diabetes 2, on medication to control, however in the last 18 months, I have noticed my penis no longer maintains a full erection (does fully engorge) additionally, in a relaxed state it seems to lose it's volume, in fact it shrinks into itself. I am circumcised however, recently I have notice smegma appearing - which hasn't happened in over forty years.....