One year ago, I had never run a marathon. My longest run was 15 miles on a treadmill. I did all of my runs solo. I was a novice runner (and still am), learning how to train, fuel, and be successful. By no means have I figured everything out, but I have learned so much in the past year, not only about how to train for a marathon, but also how to manage diabetes better.
#1 - Wake up on the lower side of normal
Waking up with a blood sugar over 150 was not good for me, or my training. I wanted my blood sugar to come down, but was always afraid of giving too much of a correction bolus. My goal was to wake up between 70 and 90. I know that seems "low," but it worked the best for me. On marathon morning, I woke up at 66 and was happy. Please remember that "low" is different for everyone. I can function fine at 66, while you might not be able to.
#2 - Consistency
I did all of my long runs in the morning, most often starting at 7 AM, the time my marathon started. I do all of my runs during the week at night due to scheduling/job/life issues, but I always did my long run in the morning to train my body to run at that time.
#3 - Eat the Same Thing
I eat the same thing 99% of the time for breakfast. Therefore, I know exactly how much insulin I need to give myself. My breakfast is not a typical runner's breakfast, but it works for me. Finding something to work for you is so important. So, what do I eat? When I answer this, most people stand and stare at me in disbelief. I eat yogurt, berries, and cereal. I also have some peanut butter and a CLIF bar before I start a long run. I do not bolus for the CLIF bar. I eat a lot in the morning because I need that much food for the quantity of running I do. I rarely need to use the bathroom, too (1 time in training in a year...not too bad!).
#4 - Know Your Nutrition Plan During the Race
Going into my marathon, I knew I was going to eat GU rocktane at miles 6, 12, and 18. I packed an extra GU to take at 22 if I felt like I needed it, but didn't end up eating it. After taking my GU, I always washed it down with water afterward. Between my GUs, I took Gatorade from the aid stations. Gatorade is tricky because sometimes one glass can be much more sugary than another. I find that I need to keep nourishing my body during the race to perform well.
#5 - Know Your Insulin Plan
Many people set temporary basals before and during exercise. However, I am not one of them. I don't touch my basal rates. I have pretty sensitive to insulin and don't have high basal rates to begin with and it causes me more issues post-exercise. I leave my basals exactly how they are and eat throughout the race (see Goal #4). I take in a lot of carbs during the race, but only take a very, very, very small bolus for all of it. During the marathon, I took a bolus of 0.2 units at mile 12 and nothing again. I ended the race at 165.
#6 - Know Your Nervousness Level
I learned this lesson the hard way. Before my ChiTown Half Marathon in April, I was not nervous at all. I had just come back from Los Angeles and was ready to run for fun. The end result was going low and having to walk over 3 miles of the race. I was so furious, mad, and frustrated by the experience. However, it ended up being a great learning experience. As I race more, I am less and less nervous. Nerves make my blood sugar go higher, so I know I need either more food or less insulin to have a good race. I did know that I would be nervous going into the marathon. However, I'm racing a half in 2 weeks and plan on taking less insulin on purpose to cover for lack of nerves.
#7 - About Carb-Loading
Runners are supposed to carb-load before their big race. However, I do not believe in carb-loading. It actually causes me to have far more problems. Eating something simple works much better for my blood sugar. I like to eat foods that I know how they will react in my body. For me, this means not eating pasta, rice, or desserts.
Please remember that these are things that I do. I am unique, and so are you. What works for me most likely will not work for you.