UCSF provides a chart of the balance between carbohydrates, proteins and fats that diabetics should limit themselves to, while a chart of foods sorted by their glycemic index is available on the International Diabetes Foundation's website. In general, carbohydrates should make up no more than 50 percent of a meal.
Carbohydrates are important for diabetics to understand because they greatly impact blood sugar levels. While they do not need to be avoided due to diabetes, carbohydrates include starches and sugars, all of which break down into glucose, or sugar that the body uses for fuel. Thus, carbohydrate intake needs to be controlled. Protein and fat should compose roughly equal parts of a meal plan, with emphasis put on lean meats or sources such as beans, nuts and tofu. However, kidney problems can limit protein intake.
Understanding the glycemic index of foods is also useful for diabetics. Focusing on carbohydrates, the glycemic index categorizes foods based on how quickly they raise the glucose level in blood. The index wheel is color-coded. Foods with high glycemic indexes such as rice are written in brown, while foods with low glycemic indexes such as lentils are written in yellow. The glycemic index allows people to control or monitor their blood glucose levels through diet, though it is not a substitute for proper medical care.