Diabetes Diet

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WHAT IS DIABETES?

Insulin

• During and immediately after a meal the process of digestion breaks carbohydrates down into sugar molecules (of which glucose is one) and proteins into amino acids.
  
  
• Right after the meal, glucose and amino acids are absorbed directly into the bloodstream, and blood glucose levels rise sharply. (Glucose levels after a meal are called postprandial levels.)
  
  
• The rise in blood glucose levels signals important cells in the pancreas, called beta cells , to secrete insulin, which pours into the bloodstream. Within ten minutes after a meal insulin rises to its peak level.
  
  
• Insulin then enables glucose and amino acids to enter cells in the body, particularly muscle and liver cells. Here, insulin and other hormones direct whether these nutrients will be burned for energy or stored for future use. (It should be noted that the brain and nervous system are not dependent on insulin; they regulate their glucose needs through other mechanisms.)
  
  
• When insulin levels are high, the liver stops producing glucose and stores it in other forms 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, with insulin being slightly higher. The blood glucose levels are then referred to as fasting blood glucose concentrations .

Type 1 Diabetes

• Beta cells in the pancreas that produce insulin are gradually destroyed. Eventually insulin deficiency is absolute.
  
  
• Without insulin to move glucose into cells, blood glucose levels become excessively high, a condition known as hyperglycemia.
  
  
• Because the body cannot utilize the sugar, it spills over into the urine and is lost.
  
  
• Weakness, weight loss, and excessive hunger and thirst are among the consequences of this "starvation in the midst of plenty."
  
  
• Patients become dependent on administered insulin for survival.

Type 2 Diabetes

• Type 2 diabetes is most common form of diabetes, accounting for 90% of cases. An estimated 16 million Americans have type 2 diabetes and half are unaware they have it. The disease mechanisms in type 2 diabetes are not wholly known, but some experts suggest that it may involve the following three stages in most patients: first stage in type 2 diabetes is the condition called insulin resistance; although insulin can attach normally to receptors on liver and muscle cells, certain mechanisms prevent insulin from moving glucose (blood sugar) into these cells where it can be used. Most type 2 diabetics produce variable, even normal or high, amounts of insulin, and in the beginning this amount is usually sufficient to overcome such resistance.
  
  
• Over time, the pancreas becomes unable to produce enough insulin to overcome resistance. In type 2 diabetes, the initial effect of this stage is usually an abnormal rise in blood sugar right after a meal (called postprandial hyperglycemia). This effect is now believed to be particularly damaging to the body.
  
  
• Eventually, the cycle of elevated glucose further impairs and possibly destroys beta cells, thereby stopping insulin production completely and causing full-blown diabetes. This is made evident by fasting hyperglycemia, in which elevated glucose levels are present most of the time.

WHAT ARE THE GENERAL GUIDELINES FOR A DIABETES DIET?

General Dietary Goals for People with Diabetes

• To achieve near normal blood glucose levels. People with type 1 diabetes or type 2 diabetes who are on insulin or oral medication must coordinate calorie intake with medication or insulin administration, exercise, and other variables to control blood glucose levels.
  
  
• To protect the heart and aim for healthy lipid (cholesterol and triglyceride) levels and control of blood pressure.
  
  
• To achieve reasonable weight. Overweight type 2 diabetics 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, rather than one that is culturally defined as desirable or ideal. Children, pregnant women, and people recovering from illness should be sure to maintain adequate calories for health.
  
  
• To manage or prevent complications of diabetes. People with diabetes, whether type 1 or 2, are at risk for a number of medical complications, including heart and kidney disease. Dietary requirements for diabetes must take these disorders into consideration.
  
  
• To promote overall health.

• Limit fats. Avoid saturated fats (found in animal products) and trans-fatty acids (hard margarines, commercial products, fast foods). In selecting fats or oils, prefer monounsaturated fats (virgin olive oil, canola oil), although also include polyunsaturated oils as well (sunflower, rapeseed). Of note, a 2001 report suggested that trans-fatty acids were a risk factor for diabetes type 2 while polyunsaturated were protective.
  
  
• Limit dietary cholesterol.
  
  
• Consume plenty of fiber-rich foods in the form of whole grains and fresh fruits and vegetables. Includes a daily choice of nuts, seeds, or legumes.
  
  
• When choosing foods with sugar, choose fresh fruits, but do so in moderation.
  
  
• Limit protein. In selecting proteins, eat in moderation and prefer fish or soy protein to poultry or meat. (Avoid, in any case, high-fat meats.)
  
  
• Reduce salt.

• Protein providing 10% to 20% total calories
  
  
• Fat providing no more than 30%, and
  
  
• Carbohydrates supplying up to 60%.

Some Specific Diets for People with Diabetes

• A simple heart-healthy diet with weight control may be sufficient for people with type 2 diabetes. One study of people with type 2 diabetes compared several diet plans: a high-carbohydrate/high-fiber diet, a low-fat diet, and a weight management diet. After 18 months all groups experienced similar and improved glycolated hemoglobin and cholesterol levels. The researchers concluded that the positive benefits of the diets were derived not from the specific regimens, but because the people in the study were attentive and focused. In other words, any healthy diet works if patients work at it.
  
  
• Intricate dietary methods are available for control of blood sugar in type 1 and more severe type 2 diabetes. The most common method for controlling blood sugar is the use of The Diabetic Exchange Lists. More sophisticated methods include counting carbohydrate grams and using the so-called glycemic index to determine the impact of carbohydrates on blood sugar.

Monitoring

• Pre-meal glucose levels of between 80 and 140 mg/dL.
  
  
• Bedtime levels of between 100 and 160.

• Normal HbA1c levels should be below 7%.
  
  
• Levels of 11% to 12% glycolated hemoglobin indicate poor control of carbohydrates. High levels are also markers for kidney trouble.

Preventing Hypoglycemia (Insulin Shock)

• Patients are at highest risk for hypoglycemia at night. Bedtime snacks may be helpful.
  
  
• Patients who intensively control their blood sugar should monitor blood levels as often as possible, four times or more per day. This is particularly important for patients with hypoglycemia unawareness.
  
  
• In adults, it is also particularly critical to monitor blood glucose levels before driving, when hypoglycemia can be very hazardous.
  
  
• Diabetic patients on therapies that put them at risk for hypoglycemia should always carry hard candy, juice, sugar packets, or commercially available glucose substitutes designed for diabetic individuals.

Other Factors Influencing Diet Maintenance

• 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.

• Patients should coordinate insulin administration with calorie intake. In general, they should eat three meals each day at regular intervals. Snacks are often required.
  
  
• They should try to take an insulin injection 30 minutes before they eat, although this timing could vary, depending on the form. Some experts recommend a fast acting insulin (insulin lispro) at each meal and a longer (basal) insulin at night.

WHAT ARE THE MAJOR FOOD COMPONENTS IN A DIABETES DIET?

Carbohydrates

• Sucrose (table sugar). Sucrose has also been associated with higher triglycerides and harmful cholesterol levels. And a 2002 study suggested that a high level of sugar consumption may reduce levels of HDL cholesterol, the so-called good cholesterol.
  
  
• Fructose (sugar molecule found in fruits). Fructose may produce a slower increase in glucose than sucrose. And a 2001 study reported that low-dose fructose boosted the ability to process glucose in the liver, an effect that could help people with poorly controlled blood glucose. (As with any sugar, however, excess use of fructose is associated with triglycerides and harmful cholesterol levels.)

Protein

• In one study, fish protein protected rats on high-fat diets against insulin resistance, while plant protein had no effect.
  
  
• A number of studies have reported that eating fish or shellfish at least once a week reduces the risk of sudden death from dangerous heart-rhythm abnormalities by more than one half. Oily fish that are high in omega-3 fatty acids, such as salmon, halibut, swordfish, and tuna, are particularly beneficial.

• It is rich in both soluble and insoluble fiber, omega-3 fatty acids, and provides all essential proteins.
  
  
• Soybeans also contain natural estrogens called isoflavones, which have positive effects on lipid levels.
  
  
• A number of studies have indicated that subjects that consume about 40 grams of soy protein each day reduce LDL by 13%, triglycerides by 11%, and increase HDL by 2%.

Fats and Oils

• Monounsaturated fatty acids. One pair of carbon atoms is missing hydrogen bonds. Found in plant products.
  
  
• Polyunsaturated fatty acids. Two or more pairs of carbon atoms are missing hydrogen bonds. Found in plant products.
  
  
• Saturated fatty acids. All carbon atoms have the maximum hydrogen bonds. Found in animal products.

• omega-3 and omega-6 polyunsaturated fatty acids, and
  
  
• omega-9 monounsaturated fatty acids.

• Saturated Fats. Saturated fats are found predominantly in animal products, including meat and dairy products. They are strongly associated with higher cholesterol levels. Although certain fatty acids in saturated fats called stearic acids may have some benefits, there is no simple methods for defining foods that contain them, so, in general, saturated fats should be avoided. (The so-called tropical oils, palm, coconut, and cocoa butter, are also high in saturated fats. Evidence is lacking, however, about their effects on the heart. The countries with the highest palm-oil intake, Costa Rica and Malaysia, also have much lower heart disease rates and cholesterol levels than Western nations.)
  
  
• Trans-fatty Acids. Trans-fatty acids are manufactured fats created during a process called hydrogenation, which is aimed at stabilizing polyunsaturated oils to prevent them from becoming rancid and to keep them solid at room temperature. Most are particularly dangerous for the heart and may pose a risk for certain cancers. And in fact, one 2001 study found that trans-fatty acids might actually increase the risk of developing diabetes type 2. Some experts believe that these partially hydrogenated fats are even worse than saturated fats because they both increase LDL and reduce HDL cholesterol levels and may have harmful effects on the linings of the arteries. One study of 80,000 nurses reported that women whose total fat consumption was 46% of total caloric intake had no greater risk in general for a heart attack than did those for whom fat represented 30% of calories consumed. Women whose diets were high in trans-fatty acids, however, had a 53% increased risk for heart attack compared to those who consumed the least of those fats. Hydrogenated fats are used in stick margarine and in many fast foods and baked goods, including most commercially produced white breads. (Liquid margarine is not hydrogenated and is recommended.) The FDA has now required that food labels include information on trans-fatty acids.

• Polyunsaturated fats are found in safflower, sunflower, corn, and cottonseed oils and fish.
  
  
• Monounsaturated fats are mostly present in olive, canola, and peanut oils and in most nuts.

• Omega-3 fatty acids: They are further categorized as alpha-linolenic acid and docosahexaenoic and eicosapentaneoic acids.
  
  
• Docosahexaenoic (DHA) and Eicosapentaneoic (EPA) Acids. Fish oils, which contain docosahexaenoic (DHA) and eicosapentaenoic acids (EPA), have anti-inflammatory and anti-blood clotting effects and may be significantly beneficial to the heart. DHA is the most unsaturated of all fatty acids. These fatty acids may reduce triglyceride levels and have modest positive effects on HDL. In patients with high triglyceride levels, but not in others, omega 3 fatty acids may increase LDL. Overall cholesterol levels are not affected. DHA appears to have specific benefits on blood pressure. The International Society for the Study of Fatty Acids and Lipids, in fact, recommends fish oil supplements for heart protection. Omega-3 fatty acids in fish may reduce risks for other disorders, including stroke, rheumatoid arthritis, asthma, ulcerative colitis, and some types of cancers.
  
  
• Alpha-linolenic Acid . Alpha-linolenic acid is a plant precursor of DHA, which means the body can convert it to DHA. Sources include canola oil, soybeans, flaxseed, and certain nuts and seeds (walnut, flax, chia and sometimes pumpkin seed). Studies have been positive about the effects on the heart of these oils or foods containing these oils.
  
  
• Omega-6 polyunsaturated fatty acids. Sources are corn, safflower, soybean, and sunflower oil. PUFA oils containing omega-6 fatty acids constitute most of the oils consumed in the US. Some omega-6 fatty acids are important for health. There is some association with a higher risk for certain cancer and some chronic diseases with diets high in omega-6 fatty acids, however.
  
  
• Omega-9 monounsaturated fatty acids: Sources are canola and olive oil. Extra virgin olive oil has been associated with lower blood pressure and a 2000 study reported that it may have specific benefits for people with diabetes type 2. Of concern is a small study reporting higher concentrations of LDL in subjects consuming an olive-oil rich diet compared to those on a sunflower or rapeseed oil rich diet.

• Some replacers, such as the cellulose gel Avicel, Carrageenan (made from seaweed), guar gum, and gum arabic, have been used for decades in many commercial foods.
  
  
• Plant substances known as sterols have long been known to reduce cholesterol by impairing its absorption in the intestinal tract. Sterols are now being isolated as sterol derivatives or as stanols (which are saturated sterols) to produce margarines (Benecol, Take Control). Benecol is derived from pine bark and Take Control from soybeans. Studies on such margarines are reporting that either two servings a day as part of a low-fat diet can lower LDL and total cholesterol. It should be noted, however, that these margarines may be hydrogenated and include some trans-fatty acids. Of further concern is the possibility that stanol may block absorption of important fat-soluble nutrients, including vitamins A, E, and D and carotenoids (compounds, such best carotene, that convert to vitamin A). One study suggested that it had no effect on the vitamins but did impair absorption of beta carotene. In people already on a low-fat diet, the addition of this margarine may not produce much additional benefit.
  
  
• Olestra (Olean) passes through the body without leaving behind any calories from fat. (It should be noted, however, that foods containing olestra still have calories from carbohydrates and proteins.) A 2000 study reported healthful changes in cholesterol levels in people who had been eating olestra for a year. Early reports of cramps and diarrhea after eating food containing olestra have not proven to be significant. Of greater concern is the fact that even small amounts of olestra deplete the body of certain vitamins and nutrients that are important for protection against serious diseases, including cancer. The FDA requires that the missing vitamins be added back to olestra products, but not other nutrients.
  
  
• Under investigation are fat substitutes derived from beta-glucan, the soluble fiber found in oats and barley (eg, Nu-Trim). They may have health benefits beyond reducing calories and replacing hydrogenated or saturated fats.

Some Examples of Healthy Foods

Vitamins and Supplements

• They can damage cell membranes and interact with genetic material, possibly contributing to the development of a number of disorders including diabetes, cancer, heart disease, cataracts, and even the aging process itself.
  
  
• Oxygen-free radicals can also enhance the dangerous properties of low-density lipoprotein (LDL) cholesterol, a major player in the development of atherosclerosis.

• Many have found little or no benefits. A very important major 2001 study, for example, found no protection against heart disease or stroke in high-risk patients. A 2000 one reported that patients who took natural forms of vitamin E at 400 IU for four to six years were not protected against cardiovascular disease. Still, the evidence is not altogether straight-forward. Vitamin E must be taken with oils or fats to have any effect, which might affect the outcome of some studies.
  
  
• Of interest, however, is a very small 2000 study reporting that when people with type 2 diabetes took high doses (1,200 IU) of vitamin E they had less evidence of inflammation in blood vessels, an indicator for a higher risk of heart disease and stroke. Another reported that vitamin E had benefits on the central nervous actions governing the heart in people with type 2 diabetes.
  
  
• Other studies have found similar benefits for people with type 1 diabetes after long term vitamin E supplementation, including beneficial effects on cholesterol levels and possible protection against kidney damage. Some experts, in fact, recommend life-long vitamin E supplements specifically for people with type 1 diabetes.

Minerals

Salt and Sodium

Caffeine and Alcohol

• Tea. Tea may have a very positive effect on the heart. Although it contains caffeine, it also is rich in flavonoids and other substances that offer protection against damaging forms of LDL. Green tea is often cited for its health benefits but black tea may also be beneficial. In one study, higher intake of black tea, particularly by women, was associated with a reduced risk for severe coronary artery disease. Tea also contains folic acid, which reduces homocysteine levels, a possible factor in coronary artery disease.
  
  
• Coffee. Unfiltered coffee (Turkish coffee, Scandinavian boiled or French pressed coffee, and espresso) contains an alcohol called cafestol, which may raise cholesterol levels. Filtered coffee does not contain this residue. On the other hand, coffee, like red wine, contains phenol, which helps prevent oxidation of LDL cholesterol. One study reported no association between coffee consumption and fatal or nonfatal heart disease after 10 years. In fact, the highest rates of fatal heart disease were in non-coffee drinkers, and women who increased their coffee intake reduced their mortality rates. Regular intake of coffee does have a harmful effect on blood pressure in people with existing hypertension. (Caffeine causes a temporary increase in blood pressure in everyone, which is thought to be harmless in people with normal blood pressure.)

WHAT ARE THE WEIGHT CONTROL AND DIETARY APPROACHES FOR TYPE 2 DIABETES?

General Approach to Weight Loss and Maintenance

• Start with realistic goals. Diet failure is extremely common and the odds of significant weight loss are poor, particularly in people with the highest weights. People embarking on a weight loss program should keep in mind that only a 5% to 10% reduction in weight, even in people who are obese, can improve health significantly. Certainly, the current unwholesome and distorted image of a super-thin female shape is a cultural idea that almost no one can or should achieve. (Anorexia, obesity's alter ego, is less common but is the other side of this dysfunctional aspect of our culture.) Obesity, however, still poses a threat to life, health, and well being, and the struggle against it is worthwhile. And obesity in children is never acceptable, unless there is a proven medical reason.
  
  
• The simplest (but still difficult) approach to weight loss is reducing calories and exercising at least 150 minutes a week. One study suggested that only about 20% of people who try to lose weight use these effective methods. (It should be noted that many physicians have limited time as well as training in nutrition and weight management and some may be tempted to prescribe diet pills, particularly when urged by the patient, even though a diet and exercise have not been tried.)
  
  
• Hunger pangs should not be taken as cues to eat. A stomach that has been stretched by large meals will continue to signal hunger for large amounts of food until its size reduces over time with smaller meals.
  
  
• Once a person has lost weight, maintenance is required. To maintain a healthy weight in our culture, everyone must make daily, even hourly, decisions about what is consumed and what is expended through activity. Such thinking, in many cases, can become automatic and not painful.
  
  
• Even repeated weight loss failure is no reason to give up. Most studies indicate that yo-yo dieting or weight cycling has no adverse psychological or physical effects. (Of some concern was a 2000 study reporting lower HDL levels, the so-called good cholesterol, in women whose weight cycled from frequent dieting. No other heart risks were evident, however.) Repeated dieting also does not impair the body's ability to burn calories efficiently.
  
  
• Weight loss, in any case, should not be the only or even the primary goal for people concerned about their health. The success of weight reduction efforts should be evaluated according to improvements in chronic disease risk factors or symptoms and by the adoption of healthy lifestyle habits, not by just the number of pounds lost.

• As a rough rule of thumb, one pound of fat equals about 3,500 calories, so one could lose a pound a week by reducing daily caloric intake by about 500 calories a day. Naturally, the more severe the daily calorie restriction, the faster the weight loss. Very-low calorie diets have also been associated with better success, but extreme diets can have some serious health consequences. [ See Box Warning on Extreme Diets.]
  
  
• To determine the daily calories requirements for specific individuals, multiply the number of pounds of ideal weight by 12 to 15 calories. The number of calories per pound depends on gender, age, and activity levels. For instance a 50-year old woman who wants to maintain a weight of 135 pounds and is mildly active might require only 12 calories per pound (1,620 calories a day). A 25-year old female athlete who wants to maintain the same weight might require 25 calories per pound 2,025 (calories a day).
  
  
• Fat intake should be no more than 30% of total calories. Most fats should be in the form of monounsaturated fats (such as olive oil) and saturated fats (found in animal products) should be avoided.

• Of some reassurance, a 2000 study compared two groups of type 2 subjects. One group increased carbohydrate intake by 10% with breakfast cereal and the other consumed the same calories with monounsaturated fat oils. At the end of six months, the cereal eating group actually had a better insulin profile than the MUFA group. There were no significant differences in cholesterol levels, body fat, or glycolated hemoglobin. [ See also The Ornish Program and Severely Fat-Restricted Diets under What Are the General Guidelines for Heart-Healthy Diets?]

WHAT ARE THE GENERAL GUIDELINES FOR HEART-HEALTHY DIETS?

• The Step 1 and Step 2 diets recommended by the American Heart Association.
  
  
• The Mediterranean Diet.
  
  
• Very low-fat diets, such as the Ornish Program.

American Heart Association Diet Recommendations