You need to eat breakfast for races. Races are done at a higher intensity than training runs. Without breakfast you do not have all the fuel available, and you are severely short-changing yourself.
When you are sleeping, your liver glycogen stores drop by about 50%. Without breakfast, you are not starting the race with a full fuel tank.
Your body will use any available fuel it can for the activity. It uses a combination of blood sugar (from glucose in the blood and carbs in the process of being digested), muscle glycogen, liver glycogen, and fat metabolism.
Muscle glycogen is used by the muscles for the activity that they are engaged in. For running, it is the muscle glycogen in your legs that is used, in addition to the other fuel sources.
But two things muscle glycogen CANNOT do: 1) it cannot raise blood sugar, and 2) it cannot be shared. The muscle glycogen in each of your muscle cells are only used by those cells, not in any other cells.
Liver glycogen can raise blood sugar, but muscle glycogen cannot!
When you skip breakfast for a race, you have diminished liver glycogen from not having eaten in a while. And you have no food being digested to provide blood sugar. So you are not starting with a full supply of your fuel resources. You are short-changing your body in two ways. You only have muscle glycogen, which as I mentioned above, cannot raise your blood sugar.
The ideal thing to do for a race is eat a complex carb breakfast, like oatmeal, and eat 2 hours before the gun. You will have some IOB, but you should also take in a few carbs right at the start to prevent the drop.
I am guessing you crashed somewhere after 30 minutes?