Diabetes is an illness in which the body does not use or produce insulin properly. Insulin is a hormone needed by the body to properly utilize sugar obtained from food. The causes of diabetes are unknown, although genetic and environmental factors appear to play roles.
There are different types of diabetes.
- Type 1 diabetes – This type of diabetes is sometimes called juvenile diabetes or insulin-dependent diabetes mellitus (IDDM). Patients with this type of diabetes must use insulin to control blood glucose levels.
- Type 2 diabetes – This type of diabetes is also called adult-onset diabetes, or non-insulin-dependent diabetes mellitus (NIDDM). Depending on severity, patients with this type of diabetes can control their condition through diet and exercise. Oral diabetes medication is used if needed. If the condition is severe, type 2 diabetics also use insulin injections.
- Gestational diabetes – This type of diabetes is known as diabetes of pregnancy. It usually goes away after the pregnancy is over.
Type 1 and type 2 diabetes have some similarities. They both share one central feature – elevated blood sugar (glucose) levels from either a lack of insulin or impaired response of the body to insulin. Insulin is a key regulator of the body’s metabolism. A diabetic diet for these conditions is similar and is important to diabetes management.
How does diet affect diabetes and blood glucose levels?
During and immediately following a meal, digestion breaks carbohydrates down into sugar molecules. Glucose is a sugar molecule. The glucose is absorbed directly into the bloodstream, and blood glucose levels rise sharply. This rise in blood glucose tells cells in the pancreas to secrete insulin, which pours into the bloodstream. Approximately ten minutes after eating, insulin rises to its peak level.
Insulin controls the ability of glucose to enter cells in the body. Insulin and other hormones direct whether nutrients will be burned for energy or stored for future use. If insulin levels are high, the liver stops producing glucose and stores it until the body needs it again.
As blood glucose levels reach their peak, the pancreas reduces the production of insulin. About two to four hours after a meal both blood glucose and insulin are at low levels.
In juvenile diabetes or type I diabetes, the cells in the pancreas that produce insulin are gradually destroyed. Eventually the body runs out of insulin completely. When insulin can’t move into cells, it stays in the blood stream. This causes blood glucose levels to become excessively high. Because the body can’t use the glucose it goes out through the urinary system and is lost. The consequences are weakness, weight loss, excessive hunger and thirst.
In type 2 diabetes, insulin can attach normally to the cells, but mechanisms prevent insulin from moving glucose to the inside of these cells where it can be used. This is called insulin resistance. Most type 2 diabetics produce normal to low amounts of insulin. In the beginning, this amount is enough to overcome insulin resistance, but over time the pancreas can’t produce enough insulin to overcome the resistance.
Perhaps the most dangerous type 2 diabetes symptom is the abnormal to extreme rise in blood sugar that occurs right after a meal. This effect is believed to be very damaging to the body.
Can healthy diet cure diabetes?
Unfortunately, the answer is no. There is no diabetes cure at present. By matching food intake to insulin needs, a diabetic person can avoid fluctuations in blood sugar. Some type 2 diabetics can limit the symptoms of diabetes and even achieve freedom from symptoms by following a diet and exercise plan, but this does not cure the disease.
What is a diabetic diet?
A diabetic diet is one that balances calories, exercise, and medication with blood glucose levels. There is no official diabetic diet. According to diabetes information from the National Institute of Diabetes and Digestive and Kidney Diseases, just about any healthy diet will help to control diabetes symptoms.
The key is to match the diet to the patient. Other factors to consider when choosing a diet are the severity of the diabetes, any other health conditions such as high blood pressure, or obesity, and the age and lifestyle of the patient.
The goals of dietary intervention are similar for each type of diabetes. A type 1 diabetes diet focuses on matching food intake to insulin. A type 2 diabetes diet focuses on weight loss or healthy eating. In both type 1 and 2 diabetes, as well as in gestational diabetes, the overall goal is to maintain a healthful diet and avoid severe fluctuations in blood sugar levels.
General guidelines for a healthy diabetic diet:
- Patients with diabetes should consume foods that contain carbohydrates (also called carbs) from whole grains, nuts, fruits, vegetables, and low-fat milk. Carbohydrates and monounsaturated fat (such as olive oil) should provide 60% to 70% of calories. The combination of these foods should depend on the calorie needs of the patient.
- Diabetics should avoid saturated fats (also called animal fats) and trans fatty acids (found in margarines, pre-prepared foods, and fast foods). It’s important to select fats or oils that are monounsaturated fats (such as olive oil and canola oil).
- Patients should try to limit protein. Protein should provide 15% to 20% total calories. Protein from fish, soy, or poultry is preferable to proteins from high-fat meats like ground beef, sausage or bacon.
- Diabetics may choose foods with sugar, (the healthiest choice in this category is fresh fruits), but these should be consumed carefully and in moderation.
- Some existing diets that are healthy for diabetic patients include:
- Therapeutic Lifestyle Changes (TLC) from the National Cholesterol Education Program.
- The Mediterranean Diet.
- Very-low-fat diets, such as the Ornish Program.
- The Dietary Approaches to Stop Hypertension (DASH) diet from the National Heart, Lung and Blood Institute. This diet has been designed specifically to help people reduce blood pressure but has been found to be very effective among diabetic patients. More information about the DASH diet can be found at http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/.
- One of the most important aspects of the diabetic diet is counting carbohydrates. To learn how to count carbohydrates accurately, the patient should make an appointment with a registered dietician.
What other treatments are there for diabetes?
Diabetes treatment consists of diet, exercise, and medication. For some type 2 diabetics, diet and exercise may be enough to control the disease. For type 1 diabetics this is not the case. Type 1 diabetics are dependent on insulin for life.
When diet and exercise are not enough, diabetes treatment for type 2 patients includes oral medication. These medications include Glucovance (glyburide), Glucotrol (glipizide), Glucophage (metformin), Precose (acarbose), Glyset (miglitol), Avandia (rosiglitzaone), Actos (pioglitazone), Prandin (repaglinide), and Starlix (nateglinide). When these oral medications are not enough, a type 2 diabetic may be prescribed insulin.
Type 1 diabetics must use insulin. Type 2 diabetics that do not respond to a type 2 diabetes diet and exercise or to oral medications must use insulin as well. Available insulins include:
- Short acting or “regular” insulin such as Humulin R, and Novolin R
- Rapidly absorbed insulin such as Humalog (lispro), and NovoLog (aspart)
- Intermediate acting insulin such as NPH, Lente, Humulin N, and Novolin N
- Long acting insulin such as Ultralente and Humulin-U
- Daily use insulin such as Lantus (glargine)
Insulin is given by injection, or by insulin pump.
In recent years, a small group of patients have undergone a transplant procedure where insulin producing cells are ‘seeded’ into the pancreas (the organ that produces insulin). For some patients this has been very successful.
Because there is no diabetes cure, diet becomes a critical part of diabetes management. Through diet, type 1 diabetics can balance their energy needs with the need for insulin and keep blood glucose levels within a healthy range.
Type 2 diabetics can keep complications at bay, and obviate the need for diabetes medication. The challenges of a healthy diabetic diet are real, and at times difficult for patients to follow. However, a diabetes diet is like any healthy diet and following a healthy eating plan can help lead to a longer, healthier life.
- American Diabetes Association. Frequently asked questions about nutrition. Available here.
- Ferri, FF. Diabetes mellitus. In: Ferri, FF. Practical guide to the care of the medical patient. 6th ed. St. Louis, MO: Mosby, Inc; 2004: 267-8.
- National Institutes of Health. National Heart, Lung, and Blood Institute. The DASH eating plan. Available here.
- National Institutes of Health. National Institute of Diabetes and Digestive and Kidney Diseases. What I need to know about eating and diabetes? Available here.
- Rakel, RR and Bope ET, Conn’s current therapy 2004. 56th ed. St. Louis, MO: Elsevier; 2004: 604.
- University of Maryland. What are the weight control and dietary approaches for type 2 diabetes? Available here.