When I was studying diabetes during my dietetic internship, the following graph (from www.ghc.org) helped me realize how food affects blood sugar.
You can see that all foods raise blood sugar to some degree. But, as you may know, carbohydrates cause the biggest rise in blood sugar. This does not mean that you should not eat carbohydrates. Carbohydrates are necessary to a healthy eating pattern and many carbs are very healthy for us to eat. They provide the energy our bodies need to function properly.
Carbohydrate foods are foods that contain sugar in one form or the other. They can be sugars, starches, or fibers. A starch is 2 or more sugars that are hooked together and must be broken down by your body before they become sugar again. Examples of carbohydrate foods are grains, beans, starchy vegetables, fruits, milk, and sweets.
When looking at a food label, know that the sugar amount is included in the total carbohydrate amount.
Protein does raise blood sugar but very little when compared to carbohydrates and the rise is much more even and spread over a longer amount of time. Fats, even less.
I hope this helps when you think about how different nutrients and foods affect blood sugar.