Hi,
Have your doctors done a Glucose tolerance test (GTT)? This will confirm whether or not you are diabetic. They take fasting bloods, get you to drink a fixed amount of lucazade or something similar and take bloods again two hours after.
As for high blood pressure and diabetes, I don't know much other than its a regular check up for all diabetics. All I can say is that diabetes affects the whole body. The excess glucose in the body damages the blood vessels and nerves as well as some of the organs if uncontrolled and that in turn causes other problems such as a high risk of stroke, heart attack, retinopathy, etc. if they can pin something on diabetes they will!
Having said all that, the correct lifestyle changes do make a positive impact and that in turn will help you keep good control.
There are a lot of folk on this forum who are very helpful and knowledgeable about our illness and I'm sure they will be able to offer some guidance.
Best wishes