For all my runs I would have a gel while stretching and one every three miles of a race. I would also take a bite of a Cliff bar every five miles. I figured a little caffeine and some good fats would help while running. I was correct in that thinking but my body has a tough time with gels and breaking down all of the other ingredients in a Cloff Bar.
With a lot of help from a great doctor I have found an alternative. As always this is what works best for me and my diabetes, it might not be for everyone but is an alternative for anyone that has stomach issues while running. The alternative is Justin's Hazlenut Butter, here is an article from shape.com (http://www.shape.com/fitness/training-plans/12-tasty-alternatives-energy-gels) that explains all the benefits. I have used Justin's on a bunch of runs and have loved the results, it gives me the energy boost I need and keeps my me from crapping out towards the end of a race!!