General Dietary Guidelines
Lifestyle changes of diet and exercise are extremely important for people who have pre-diabetes, or who are at high risk of developing type 2 diabetes. Lifestyle interventions can be very effective in preventing or postponing the progression to diabetes. These interventions are especially important for overweight people. Even moderate weight loss can help reduce diabetes risk.
The American Diabetes Association recommends that people at high risk for type 2 diabetes eat high-fiber (14g fiber for every 1,000 calories) and whole-grain foods. High intake of fiber, especially from whole grain cereals and breads, can help reduce type 2 diabetes risk.
Patients who are diagnosed with diabetes need to be aware of their heart health nutrition and, in particular, controlling high blood pressure and cholesterol levels. [Specific information on diet plans such as the salt-restricting Dietary Approaches to Stop Hypertension (DASH), and the Mediterranean Diet (which is rich in fruits, vegetables, fiber, and monounsaturated fats) can be found in In-Depth Report #43: Heart-healthy diet.]
For people who have diabetes, the treatment goals for a diabetes diet are:
- Achieve near normal blood glucose levels. People with type 1 diabetes and people with type 2 diabetes who are taking insulin or oral medication must coordinate calorie intake with medication or insulin administration, exercise, and other variables to control blood glucose levels.
- Protect the heart and aim for healthy lipid (cholesterol and triglyceride) levels and control of blood pressure.
- Achieve reasonable weight. Overweight patients with type 2 diabetes who are not taking medication should aim for a diet that controls both weight and glucose. A reasonable weight is usually defined as what is achievable and sustainable, and helps achieve normal blood glucose levels. Children, pregnant women, and people recovering from illness should be sure to maintain adequate calories for health.
Overall Guidelines. There is no such thing as a single diabetes diet. Patients should meet with a professional dietitian to plan an individualized diet within the general guidelines that takes into consideration their own health needs.
For example, a patient with type 2 diabetes who is overweight and insulin-resistant may need to have a different carbohydrate-protein balance than a thin patient with type 1 diabetes in danger of kidney disease. Because regulating diabetes is an individual situation, everyone with this condition should get help from a dietary professional in selecting the diet best for them.
Several good dietary methods are available to meet the goals described above. General dietary guidelines for diabetes recommend:
- Carbohydrates should provide 45 - 65% of total daily calories. The type and amount of carbohydrate are both important. Best choices are vegetables, fruits, beans, and whole grains. These foods are also high in fiber. Patients with diabetes should monitor their carbohydrate intake either through carbohydrate counting or meal planning exchange lists.
- Fats should provide 25 - 35% of daily calories. Monounsaturated (such as olive, peanut, canola oils; and avocados and nuts) and omega-3 polyunsaturated (such as fish, flaxseed oil, and walnuts) fats are the best types. Limit saturated fat (red meat, butter) to less than 7% of daily calories. Choose nonfat or low-fat dairy instead of whole milk products. Limit trans-fats (such as hydrogenated fat found in snack foods, fried foods, and commercially baked goods) to less than 1% of total calories.
- Protein should provide 12 - 20% of daily calories, although this may vary depending on a patient’s individual health requirements. Patients with kidney disease should limit protein intake to less than 10% of calories. Fish, soy, and poultry are better protein choices than red meat.
- Lose weight if body mass index (BMI) is 25 - 29 (overweight) or higher (obese).
Several different dietary methods are available for controlling blood sugar in type 1 and insulin-dependent type 2 diabetes:
- Diabetic exchange lists (for maintaining a proper balance of carbohydrates, fats, and proteins throughout the day)
- Carbohydrate counting (for tracking the number of grams of carbohydrates consumed each day)
- Glycemic index (for tracking which carbohydrate foods increase blood sugar)
Tests for Glucose Levels. Both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) are of concern for patients who take insulin. It is important, therefore, to monitor blood glucose levels carefully. Patients should aim for the following measurements:
- Pre-meal glucose levels of 70 - 130 mg/dL
- Post-meal glucose levels of less than 180 mg/dL
[For more information, on blood sugar monitoring, see In-Depth Reports #9: Diabetes type 1 and #60: Diabetes type 2.]
Hemoglobin A1C Test. Hemoglobin A1C (also called HbA1c or HA1c) is measured periodically every 2 - 3 months, or at least twice a year, to determine the average blood-sugar level over the lifespan of the red blood cell. While fingerprick self-testing provides information on blood glucose for that day, the A1C test shows how well blood sugar has been controlled over the period of several months. For most people with well-controlled diabetes, A1C levels should be at around 7%.
Other Tests. Other tests are needed periodically to determine potential complications of diabetes, such as high blood pressure, unhealthy cholesterol levels, and kidney problems. Such tests may also indicate whether current diet plans are helping the patient and whether changes should be made. Periodic urine tests for microalbuminuria and blood tests for creatinine can indicate a future risk for serious kidney disease.
Other Factors Influencing Diet Maintenance
Food Labels. Every year thousands of new foods are introduced, many of them advertised as nutritionally beneficial. It is important for everyone, most especially people with diabetes, to be able to differentiate advertised claims from truth. Current food labels show the number of calories from fat, the amount of nutrients that are potentially harmful (fat, cholesterol, sodium, and sugars) as well as useful nutrients (fiber, carbohydrates, protein, and vitamins).
Labels also show "daily values," the percentage of a daily diet that each of the important nutrients offers in a single serving. This daily value is based on 2,000 calories, which is often higher than what most patients with diabetes should have, and the serving sizes may not be equivalent to those on diabetic exchange lists. Most people will need to recalculate the grams and calories listed on food labels to fit their own serving sizes and calorie needs.
Weighing and Measuring. Weighing and measuring food is extremely important to get the correct number of daily calories.
- Along with measuring cups and spoons, choose a food scale that measures grams. (A gram is very small, about 1/28th of an ounce.)
- Food should be weighed and measured after cooking.
- After measuring all foods for a week or so, most people can make fairly accurate estimates by eye or by holding food without having to measure everything every time they eat.
Timing. Patients with diabetes should not skip meals, particularly if they are taking insulin. Skipping meals can upset the balance between food intake and insulin and also can lead to low blood sugar and even weight gain if the patient eats extra food to offset hunger and low blood sugar levels.
The timing of meals is particularly important for people taking insulin:
- Patients should coordinate insulin administration with calorie intake. In general, they should eat three meals each day at regular intervals. Snacks are often necessary.
- Some doctors recommend a fast acting insulin (insulin lispro) before each meal and a longer (basal) insulin at night.
Special Considerations for People with Kidney Failure
Diabetes can lead to kidney disease and failure. People with early-stage kidney failure need to follow a special diet that slows the build-up of wastes in the bloodstream. The diet restricts protein, potassium, phosphorus, and salt intake. Fat and carbohydrate intake may need to be increased to help maintain weight and muscle tissue.
People who have late-stage kidney disease usually need dialysis. Once patients are on dialysis, they need more protein in their diet. Patients must still be very careful about restricting salt, potassium, phosphorus, and fluids. Patients on peritoneal dialysis may have fewer restrictions on salt, potassium, and phosphorus than those on hemodialysis.