Hi mannings3 and welcome,
First read the sticky on the first Page:
Newly diagnosed with PC? – read this thread firstThat'll give you a good layman's background. It also has a recommendation to get a second opinion on your biopsy slides from Bostwick or Epstein - it's really a good idea, even if you have to pay out of pocket.
I'm sorry your health is poor, and especially with your diabetes, I can see why they'd steer you away from surgery.
The term "active surveillance" means there's an intent to treat with surgery or radiation at some future time if the cancer shows signs of progressing. There's a related idea called "watchful waiting" that means you watch the progression closely, and if it does progress beyond some point, you only treat it with non-curative hormone therapy. A man can live with prostate cancer and hormone therapy quite a long time before it progresses to a point where it is fatal. So especially when there are other diseases at work, watchful waiting can be a good option. It's something to consider carefully and discuss with your family and your doctor.
You might be a candidate for brachytherapy - there are two kinds - low dose rate also known as seeds, or high dose rate also known as temporary implants. You have to find and talk to an expert in each kind.
As far as external beam radiation goes, the traditional course is 40-44 treatments (called IMRT), but some doctors are doing it in fewer treatments (called "hypofractionated IMRT"), and you can even get it done in just 5 treatments (called SBRT or sometimes known as CyberKnife). The results are equally good. In fact, the side effects may be lower with fewer treatments. Fatigue especially is very rare with SBRT but common with the extended treatments.
The only hard part is that you have to seek out and talk to specialists in each one of those therapies, and make up your own mind about
which is right for you. If you tell us where you are, we may be able to recommend specialists in your area.