EJ, just a couple things...
How much have your symptoms changed in the past year? It is unlikely that a colonoscopy one year after your previous one will show drastically different results; would it be possible to get a copy of your last scope report (plus pictures) to show to your new GI? It might eliminate the need for a repeat scoping. And that might eliminate your anxiety!
You say you have lower abdominal pain and joint pain...which joints are you having pain in?
The most important issue in getting diabetes (type 2) under control is maintaining a healthy weight. It is hard to change eating habits we've developed over the past 20-some-odd years, but if your habits are leading to potentially chronic health problems, it's worth it to change them. Have you ever kept a food diary, by any chance? It might elucidate the possible cause of some of your symptoms. Also (from personal experience, I might add), it could help you develop better eating habits - when you're recording everything you eat, it's hard not to notice bad habits!