Hi! If you're taking a four-hour exam, you'll want to feel alert and not hungry. What has always worked for me is an omelet with some cheese and a vegetable or two like broccoli, bell pepper, or mushrooms (whatever you like) with a slice or two of Canadian bacon. Canadian bacon is not breakfast bacon but ham slices. If you must have bread, eat one slice of a whole grain with a pat of butter.
Snacks could be a couple of string cheese sticks, baggies of nuts, a small cup of yogurt (not with sugar).
If you are insulin resistant, your blood sugar may bounce according to what you eat and if you eat a lot of carbs at one sitting, then you may feel tired or sleepy an hour or two after eating.
I hope your test goes well!
diabetes type 2 controlled by diet and exercise and
very low carb way of eating