You might enjoy reading on Team Type 1 if you are not familiar with them. They don't all have Type 1 but I was impressed (amazed, humbled) to find out some of the pros ride with insulin pumps and are really on top of their nutrition so they can compete at the higher levels.
I find small group rides to be best. Then I feel like I can try some things but can also walk a section I don't feel like I want to ride. In the summer I do a Monday night women's ride that we usually have 6 or so people per group. We might have 8 with a leader and sweep. It is a good amount, 12 would be too much for me personally on the trail.
Even though I don't have a medical issue such as yours, I have had to bail on a group ride this summer because I overheated and got sick to the point that I had to throw up. It is embarrassing but everyone has been there or will be there.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan