I agree with most of what everyone here has already said. I've run three marathons since being diagnosed with diabetes and I found that managing my blood sugar so that I could run well (vs. running to manage blood sugar) has been one of the biggest challenges to living with diabetes. I was a long distance runner before being diagnosed, and I did not want to give it up -- of course you don't have to, but it's harder.
I am working with the Young Leadership Committee at the NYC chapter of JDRF to potentially develop some additional features for Juvenation, and / or the JDRF site. We are thinking of adding forums and resources for specific things like long distance running. I eventually found a great nutritionist, met successful runners with type 1, and talked to running coaches, and was able to run my fastest marathon. The people and information is out there, but it's not in one place. If you would be interested in a more organized forum, specifically for long distance running, please email me with comments and thoughts (firstname.lastname@example.org). Or if you'd like to see a forum for something else -- cycling, swimming, or more career oriented, like being a surgeon. Please let me know!
My running system is 15g of carbs before I head out the door, and half a gu (about 10g carbs) at 40 minutes and every 20 minutes thereafter. I aim to be above 100 when I start and around 140 when I finish. Your carb intake will depend on your weight, gender, distance you're running, speed, and metabolic rate. A nutritionist can help you figure this all out.
I run halfs and fulls and am looking on getting into Ultras too! Have you heard of Glucomotive or Insulindependence? Depending on where you live you might have a club in your area already of all Type 1s that you could join!! www.glucomotive.org a great place to meet fellow T1s who run with diabetes!!
Have you tried changing your basal rates on race day depending on the distance? Race day vs training day basals will vary. Tons of info out there and lots of people doing crazy things with diabetes. Just have to find the group for you! For short runs less than 5miles I don't touch my basal. Anything longer than an hour I lower my basal two hours beforehand and have a 15-30g snack about 30mins in. For race day, the basal needs go UP at the starting line and then go down throughout the race... the whole adrenaline thing is always sneaky.
I ran my first marathon in October 2011. Trying to control my diabetes during training and the race was definitely an adventure, but I was successful. I finished the marathon in 4 hours 57 minutes. I was hoping for a bit faster but it was hot in Chicago that day. I've been T1 for 14 years and doing multiple injections the entire time. Training for the marathon is what finally has convinced me that a pump in the way to go. I have my next check up with my endo in February, and I'm going to start the process. There were times during training where my sugar was over 300 during a 16 miler but I couldn't keep insulin in my fanny pack because it would be too hot in there. I know that a pump will give me tighter control and help me to be able to race better and stronger.
As far as nutrition, I would always eat a ricecake with peanut butter about an hour before a run. During a long run or race, I would use Clif shots, a banana, gluten free pretzels, and/or Gatorade. I felt strong during the race and never really hit a "wall;" just felt tired and ready to be done.