A glucose meter is used to test how much sugar is in your blood. Knowing your blood sugar levels can be useful for diabetics or anyone following a low-glycemic diet. Most people experience a rise in blood sugar after a meal, and this rise can be especially high if you eat carbohydrates. Using a glucose monitor after each meal can help you determine which foods cause a blood sugar spike. If you check your blood sugar with a glucose monitor and find that it is too high, you might try eating something high in protein and healthy unsaturated fats, such as a handful of nuts, to help even it out.