Although both are related to red blood cells they don't appear to be connected. Diabetes type 2 is associated with excess sugar binding to RBC's where PRV is associated with excess RBC's produced by an abnormality of the bone marrow. Neither has a cure but both can be treated to prevent further escalation. If left untreated and ignored the possibility of a stroke or heart attack can be imagined, among other health issues. Hope you're in full dialog with your attending physician/s on the "what to do's". Good luck
my father has both, complications he has are to do with his spleen, half of it has died and was removed several years ago. The remaining part became enlarged and if removed would be dangerous as he's diabetic. He also gets very bad ulcers from some of the meds he had been put on and can take up to a year to heal. My father is now on a drugs trial as he's running out of options, he has seen an improvement on his spleen and looks better than I have seen him in the last year.