Diabetes Diet

Description

Alternative Names

Major Food Components

Carbohydrates

Compared to fats and protein, carbohydrates have the greatest impact on blood sugar. Evidence now suggests that it is the total amount of carbohydrates rather than the specific type that most directly affects blood glucose.

Carbohydrate types are either complex (as in starches) or simple (as in fruits and sugars). One gram of carbohydrates equals four calories. The current general recommendation is that carbohydrates should provide between 50% and 60% of the daily caloric intake.

Complex Carbohydrates. In all cases, complex carbohydrates found in whole grains and vegetables are preferred over those found in starch-heavy foods, such as pastas, white-flour products, and potatoes. Most of these are high in fiber, which is important for health. Whole-grains specifically are extremely important for people with diabetes or at risk for it. [For specific benefits, see Box Whole Grains, Nuts, and Fiber-Rich Foods and see Table Some Examples of Healthy Foods.]

Simple Carbohydrates (Sugar). Sugars are generally one of two types:

• 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 blood sugar than sucrose, which may have some advantages for people with diabetes. Dark-colored fruits are rich in important vitamins and other nutrients, and studies continue to report their benefits for the heart and health in general. Other fruits, such as apples and grapes also have important food chemicals. (As with any sugar, however, excess use of fructose is associated with triglycerides and harmful cholesterol levels.)

Sugar itself, either as sucrose or fructose, adds calories, increases blood glucose levels quickly, and provides no other nutrients. High level of sugar consumption--whether fructose or sucrose--has been associated with higher triglycerides and lower levels of HDL cholesterol, the so-called good cholesterol. And the high consumption of sugar is most likely one of the factor in the current obesity epidemic. Soda, other sweetened beverages, and fruit juice in fact may be singled out as major contributors to childhood obesity.

People with diabetes should continue to avoid products listing more than 5 grams of sugar per serving, and even fruit intake should be moderate. If specific amounts are not listed, patients should avoid products with either sucrose or fructose listed as one of the first four ingredients on the label. [See Box Fat Substitutes and Artificial Sweeteners.]

Of increasing interest to researchers in the study of possible harm from sugar are advanced glycation end-products (called AGEs), which are end-products of the chemical reaction between sugar and protein. This reaction occurs most intensively when cooking at high temperatures--particularly animal fats. (Steaming or cooking food in water does not produce these chemicals. Low, slow cooking also produces fewer AGEs.) AGEs can also be formed by chemical reactions in the body itself. They are now believed to promote factors in the inflammatory response that cause a number of diseases or their complications, including diabetes and other serious conditions (e.g., Alzheimer's, atherosclerosis, cataracts, and osteoporosis).

The Carbohydrate Counting System. Some people plan their carbohydrate intake using a system called carbohydrate counting. It is based on two premises:

• All carbohydrates (either from sugar or starch) will raise blood sugar to a similar degree. In general, one gram of carbohydrates raises blood sugar by 3 points in people who weigh 200 pounds, 4 points for weights of 150 pounds, and 5 points for 100 pounds.

• Carbohydrates have the greatest impact on blood sugar; fats and protein play only minor roles.

In other words, the amount of carbohydrates eaten (rather than fats or proteins) will determine how high blood sugar levels will rise. There are two options for counting carbohydrates: advanced and simple. Both rely on the collaboration with a physician, dietitian, or both. Once the patient learns how to count carbohydrates and adjust insulin doses to their meals, many find it more flexible, more accurate in predicting blood sugar increases, and easier to plan meals than other systems.

The basic goal is to balance insulin with the amount of carbohydrates eaten in order to control blood glucose levels after a meal. The steps to the plan are as follows:

The patient must first carefully record a number of factors that are used to determine the specific requirements for a meal plan based on carbohydrate grams:

• Multiple blood glucose readings (taken several times a day).

• The time of meals.

• Amount in grams of all the carbohydrates eaten.

• Time, type, and duration of exercise.

• The time, type, and dose of insulin or oral medications.

• Other relevant factors, such as menstruation, illness, and stress.

The patient works with the dietitian for two or three 45 to 90 minute sessions to plan how many grams of carbohydrates are needed. There are three carbohydrate groups:

• Bread/starch.

• Fruit.

• Milk.

One serving from each group should contain between 12 and 15 carbohydrate grams. (Patients can find the amount of carbohydrates in foods from labels on commercial foods and from a number of books and web sites.)

The dietitian creates a meal plan that accommodates the patient's weight and needs, as determined by the patient's record, and makes a special calculation called the carbohydrate to insulin ratio. This ratio determines the number of carbohydrate grams that a patient needs to cover the daily pre-meal insulin needs.

Eventually, patients can learn to precisely adjust their insulin doses to their meals.

It should be noted that patients who choose this approach must still be aware of protein and fat content in foods. They may add excessive calories and saturated fats. Patients must still follow basic healthy dietary principles.

The Glycemic Index. The glycemic index has been developed to determine which carbohydrate-containing food raise blood glucose levels more or less quickly after a meal. The index uses a scale of numbers for specific foods that reflect greatest to least delay in producing an increase in blood sugar after a meal. The lower the index number, the better the impact on glucose levels. Some evidence suggests that the benefit of foods with a low glycemic index is due to their ability to increase insulin levels quickly and so remove blood sugar rather than their ability to slow the release of blood sugar itself.

There are currently two indexes in use. One uses a scale of 1 to 100 with 100 representing a glucose tablet, which has the most rapid effect on blood sugar [SeeTable The Glycemic Index of Some Foods.] The other common index uses a scale with 100 representing white bread (so some foods will be above 100).

A major 2003 analysis suggested that choosing foods with a low glycemic index scores may have a small but significant effect on controlling the surge in blood sugar after meals. Many of these food are also high in fiber and so have heart benefits as well. Substituting low- for high-glycemic index foods may even help prevent weight gain.

One easy way to improve ones glycemic index is simply to replace starches and sugars with whole grains and legumes (e.g., dried peas, beans, and lentils). However, there are many factors that affect the glycemic index of foods, and maintaining a diet with low glycemic load is not straightforward. The following are some considerations:

• The numbers attributed to each carbohydrate-rich food are not additive. In other words, adding All Bran cereal (index of 49) to a banana (index of 61) does not equal 110.

• Adding certain fats to a food, for example butter to potato, can slow down the potato's impact on blood sugar. One study reported that when patients ate fatty foods first, their blood glucose levels were significantly lower an hour after the meal than when carbohydrates were eaten first.

• Adding foods with organic acids (e.g., pickles, yogurt) to meals may reduce the impact of foods with high glycemic scores on blood sugar. (It should be noted that yogurt alone, however, has the same high glycemic index as regular milk.)

No one should use the glycemic index as a complete dietary guide, since it does not provide nutritional guidelines for all foods. It is simply an indication of how the metabolism will respond to certain carbohydrates. Some experts believe it is too complicated to be practical and that simply tracking carbohydrates, eating healthily, and maintaining a healthy weight is sufficient. Nevertheless, a study on children with type 1 diabetes suggested that it offered as many choices as the exchange diet and they did not report feeling any greater limitations.

Protein

In general, experts recommend that proteins should provide 12% to 20% of calories. This daily amount of poses no risk to the kidney in people without signs of nephropathy. Protein is important for strong muscles and bones. Protein intake in diabetes is complicated, however:

• Some evidence also suggests that a high-protein diet lowers post-meal blood sugar more effectively than standard diets. This might be specifically help for patients with type 2 diabetes.

• On the other hand, protein restriction may be important for insulin-dependent diabetic patients with kidney disease. Evidence now strongly indicates that even moderate restriction of proteins may help slow the progression of nephropathy. A 1999 study indicated that a strict-low protein diet may even delay the need for dialysis in patients with kidney failure. All major studies on restricting protein have used insulin-dependent patients as subjects. It is not yet known if lowering protein would have the same benefits for diabetics with nephropathy who are not insulin-dependent. (Note: Diets that are severely low in both protein and salt and coupled with high fluid intake increases the risk for hyponatremia, a rare condition that can cause fatigue, confusion, and, in extreme cases, can be life-threatening.)

One gram of protein contains four calories. Protein is commonly recommended as part of a bedtime snack to maintain normal blood sugar levels during the night, although studies are mixed over whether it adds any protective benefits against nighttime hypoglycemia. If it does, only small amounts (14 grams) may be needed to stabilize blood glucose levels.

Fish. Fish is probably the best source of protein. Evidence suggests that eating moderate amounts of fish (twice a week) may improve triglyceride and help lower the risks for death from heart disease, dangerous heart rhythms, blood pressure, a tendency for blood clots, and the risk for stroke.

It should be noted that a French study reported a higher incidence of heart attack in men who ate fish daily. Such findings may be due to mercury toxicity, which has harmful effects on the heart. High mercury content has been observed in swordfish and shark and, to a medium extent, in tuna, trout, pike, tilapia (tile fish) and bass.More research is needed to further define the risks and benefits of fish, but at this time most evidence for eating fish two or three times a week is highly positive for most people. [See Beneficial Fats and Oils under Fats and Oils, below.]

Soy. Soy is an excellent food. It is rich in both soluble and insoluble fiber, omega-3 fatty acids, and provides all essential proteins. Not all studies are consistent, but the majority has shown an improvement in at least one of the cholesterol components in people who consumed at least 25 grams of soy protein. Soy may also reduce other heart risk factors, including blood pressure, at least in certain populations.In one 2002 study, soy was associated with better control of blood sugar and lower LDL levels in postmenopausal women with type 2 diabetes. The best sources are soy products (tofu, soy milk) or whole soy protein. Adding soy to lean ground beef may still provide heart benefits and be more acceptable for people who object to soy's taste or its "veggie" image. (Note: Tablets of individual isoflavones--chemicals, such as genistein or daidzein, found in soy--do not appear to offer any advantages. Soy sauce is also not a good source. It contains only a trace amount of soy and is very high in sodium.)

More research is important to determine if soy has long-term complications. Of possible concern, a high intake of soy during pregnancy may have some adverse effect on the fetus, although only animal studies have suggested this.

Meat and Poultry. For heart protection, one 1999 study suggested that it didn't matter if you chose fish, poultry, beef, or pork as long as the meat was lean. (Saturated fat in meat is the primary danger to the heart.) The fat content of meat varies depending on the type and cut. It is best to eat skinless chicken or turkey. However, the leanest cuts of pork (loin and tenderloin), veal, and beef are nearly comparable to chicken in calories and fat and their effect on LDL and HDL levels. It should be noted, however, that even chicken and lean meat do not improve cholesterol levels, and, in terms of cardiac health, fish is a more desirable choice.

Dairy Products. A 2002 study reported a lower incidence of factors related to type 2 diabetes and heart disease (insulin resistance, high blood pressure, obesity, and unhealthy cholesterol) with a high intake of dairy products, including those with a high-fat content. Some researchers suggest the calcium in dairy products may be partially responsible for these benefits. The effects of extra calcium on blood pressure, however, are mixed with some even showing higher pressure. Because many dairy products are high in saturated fats, which are related to heart disease, this study requires confirmatory evidence.

Fats and Oils

Some fat is critical in everyone's diet, but certain fats have good or harmful effects on health, depending on their chemistry. All fats, good or bad, are high in calories compared to proteins and carbohydrates. In order to calculate daily fat intake, multiply the number of fat grams eaten by nine (one fat gram is equal to 9 calories, whether it's oil or fat) and divide by the number of total daily calories desired. One teaspoon of oil, butter, or other fats equals about five grams of fat. All fats, no matter what the source, add the same calories.

People should strive to replace saturated (animal fats) and transfatty acids (commercial fats) with unsaturated fats from plant and fish oils. The American Heart Association and other experts now recommend that the source of most of these unsaturated fats should come from omega-3 fatty acids, which are found in fish and plant sources.

The Chemistry of Fats and Cholesterol. Most of the cholesterol in the body does not come from food but is produced by the liver--stimulated by saturated fats. The dietary key to managing cholesterol, then, lies in understanding some of the major compounds in fats and oils that are becoming important in health:

• Fatty Acids. All fats and oils found in foods are made up of chains of molecules called fatty acids. There are three major chains: saturated fatty acid (found mostly in animal products) and two unsaturated fatty acids--monounsaturated and polyunsaturated fatty acids (found in plant products). The oils and fats that people and animals eat are nearly always mixtures of these three chains, but one type of fatty acid usually predominates in specific oils or fats.

• Essential Fatty Acids. In addition, there are three chemical subgroups of polyunsaturated fatty acids called essential fatty acids: omega-3 and omega-6 polyunsaturated fatty acids, and omega-9 monounsaturated fatty acids.

• Transfatty Acids. To complicate matters, there are also trans-fatty acids, which are not natural but are manufactured by adding hydrogen atoms to polyunsaturated fatty acids (called hydrogenation).

Harmful Fats. Reducing consumption of saturated fats and trans-fatty acids is the first essential step in managing cholesterol levels through diet.

• Saturated Fats. Saturated fats are found predominantly in animal products, including meat and dairy products. They are strongly associated with higher cholesterol level and have been associated with a higher risk for type 2 diabetes. They may be even more dangerous in women than in men. Avoiding fats during the evening meal may be especially helpful. High-fat meals are associated with sudden surges in triglyceride levels and other lipids along with impaired blood flow in the arteries to the heart. (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. Studies report that high consumption of these fats reduces HDL cholesterol levels, has harmful effects on the linings of the arteries, and may increase the risk for diabetes type 2. In one study, women whose diets were high in trans-fatty acids had a 53% increased risk for heart attack compared to those who consumed the least of those fats. Some experts believe that these partially hydrogenated fats are even worse for the heart than saturated fats. They may also pose a risk for certain cancers. 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.

Beneficial Fats and Oils. It should be noted that some fat is essential for health, and fat is essential for healthy development in children. Public attention has mainly focused on the possible benefits or hazards of monounsaturated (MUFA) and polyunsaturated (PUFA) fats.

• 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. (Canola is the most unsaturated of all the fats.) Some studies have reported that replacing carbohydrates with monounsaturated fats improves glucose control after meals and reduces triglycerides in people with type 2 diabetes.A study on type 1 patients also reported improved cholesterol levels. Diabetic patients who are overweight, however, should be conscious of the calories in any oils.

Researchers are most interested in the smaller fatty-acid building blocks contained in both oils, which may have more specific effects on lipids. Three important fatty acids are the essential fatty acids omega-3, omega-6, and omega-9.

Omega-3 fatty acids are found in fish oil (docosahexaenoic and eicosapentaneoic acids) and plants (alpha-linolenic acid).

• Docosahexaenoic (DHA) and Eicosapentaneoic (EPA) Acids. DHA and EPA are found in fish oils, and evidence suggests that they have significant benefits for the heart, including reducing sudden death from heart disease, dangerous heart rhythms, inflammation, blood clotting factors, blood pressure, and improving triglyceride levels. Fish oil has little effect on LDL or HDL levels. Its effects on blood glucose levels in people with type 2 diabetes are unclear. These fatty acids may also reduce risks for other disorders, including stroke, rheumatoid arthritis, asthma, ulcerative colitis, some cancers, and mental decline. Three capsules of DHA-EPA supplements are about equivalent to eating one serving of fish.The richest sources of omega-3 fatty acids are oily fish, such as salmon, mackerel, or sardines. [For more information, see Fish under Protein.]

• 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). Some, but not all, studies suggest that oils or foods containing these oils may also be heart-protective. Supplements or foods containing these oils may also protect the heart. For example studies have reported heart protection from flaxseed supplements and also from nuts, such as almonds, macadamia, and walnuts. Nuts are high in calories, although studies in 2002 reported that replacing usual snacks with almonds did not affect the daily diet and significantly reduced cholesterol and other heart disease risk factors. Still, people must be aware of that nuts are not low-calorie snacks.

Omega-6 polyunsaturated fatty acids are found in 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. However, high intake of these fats was associated in one study with weight gain in the abdomen (the so-called apple shape), a risk factor for heart disease.High consumption is also associated with a higher risk for certain cancer and some chronic diseases.

Omega-9 monounsaturated fatty acids are contained in canola and olive oil. Both oils have been associated with health protection.

Research suggests that a healthy balance of all these fats may be important and that our current Western diet contains an unhealthy ratio of omega-6 to omega-3 fatty acids (10 to 1). Omega-9 fatty acids may also contain chemicals that block harmful factors found in omega-6 fatty acids. Researchers are finding then that the most benefits may be found in mixture of all three fatty acids found in both poly- and monounsaturated oils, but in modest amounts that do not add too many calories.

Fat Substitutes. Fat substitutes added to commercial foods or used in baking, deliver some of the desirable qualities of fat, but do not add as many calories. [See Box Fat Substitutes and Artificial Sweeteners.]

Dietary Cholesterol

The story on cholesterol found in the diet is not entirely straightforward. Cholesterol is found only in animal tissues, with high amounts occurring in meat, dairy products, egg yolks, and shellfish. The American Heart Association recommends no more than 300 mg of cholesterol per day. One study estimated, however, that reducing dietary cholesterol intake by 100 mg/day would only produce a 1% decrease in cholesterol levels. Of note, however, are studies indicating that although dietary cholesterol itself does not appear to increase the risk for heart disease in most individuals, people with diabetes, especially type 2, may be an exception. Until more research is done, they should consider avoiding eating eggs or other high-cholesterol foods (such as shrimp) more often than once a week.

Vitamins and Supplements

The value of specific vitamins on health in general and for individual diseases is unclear. Nevertheless, of interest was a 2003 study reporting a significantly lower rate of infections (17%) in people with type 2 diabetes who took a multivitamin and mineral supplement compared to those who took a placebo (93%).

Antioxidant Vitamins E, C, and A. Deficiencies in Vitamins E and beta carotene have been linked to heart disease and also to higher blood glucose levels. These nutrients as well as vitamins C and A have antioxidant effects and other properties that should benefit the heart. However, a number of studies have found no reductions in heart disease in people who have taken antioxidant vitamins. In 2003, the US Preventive Service Task Force concluded that, to date, evidence is insufficient to confirm or refute the benefits of supplements of any of these vitamins in protecting against heart disease. It is important to note, in addition, that each of these supplements may even be harmful to the heart in high doses. [See Box Antioxidants: Pros and Cons.]

Folate and B12 Vitamins. Deficiencies in the B vitamins folate (known also as folic acid) and B12 have been associated with a higher risk for heart disease in some (but not all) studies. Such deficiencies produce elevated blood levels of homocysteine, an amino acid that has been associated with a higher risk for heart disease, stroke, and heart failure. Some studies in 2002, suggest that any risk posed by homocysteine or benefits from folic acid for heart disease are at most modest. One study, however, reported lower failure rates after angioplasty in patients who took folic acid and vitamins B12 and B6. And a major 2002 suggested that lowering homocysteine levels with folic acid would reduce the risk for heart disease by 16% and stroke by 24%. More evidence is needed to determine whether homocysteine plays a causal role in cardiovascular disease and whether the B vitamins are protective. Folate improves blood flow through the arteries, which may be important for the heart, regardless of its effect on homocysteine.

Niacin. Niacin (vitamin B3) is used for lowering unhealthy cholesterol levels. Although vitamin B3 is available over the counter, it can have significant side effects. A physician should prescribe niacin in order to ensure its safety and effectiveness.

[For more information, see Well-Connected Report #39 Vitamins, Carotenoids, and Phytochemicals.]

Salt and Sodium

Most experts recommend salt restriction in people who are hypertensive. Some people, however, are much more sensitive to harmful effects from salt than others:

• People at Risk for Salt-Sensitivity (African Americans, Diabetics, the Elderly). About half of people with hypertension have blood pressure that reacts significantly to salt. Such people are known to be salt-sensitive. High-salt diets in anyone who is salt-sensitive may harm the heart, kidney, and brain and increase the risk for death, regardless of their blood pressure. (Even people with normal blood pressure can be salt-sensitive.) Among those at highest risk for salt sensitivity are African Americans, people with diabetes, and elderly people. A 2001 study, for example, reported that reducing sodium intake in older people, including African Americans, was very effective in controlling their hypertension. Still because testing for salt-sensitivity is not easy, experts recommend that everyone proactively restrict their daily salt-intake.

• Overweight People. Overweight individuals may absorb and retain sodium differently from people with normal weights. In fact, one 1999 study reported that high sodium intake was associated with an increased risk of heart disease and all cause mortality in overweight, but not in normal weight, people. Unfortunately, because overweight people generally consume more calories, they are also likely take in more sodium.

Simply eliminating table and cooking salt can be beneficial. It should be noted, however, that about 75% of the salt in the typical American diet comes from processed or commercial foods, not from food cooked at home, so the benefits of table-salt substitutes are likely to be very modest. Some sodium is essential to protect the heart, but most experts agree that the amount is significantly less than that found in the average American diet. If people cannot significantly reduce the amount of salt in their diets, adding potassium-rich foods might help to restore a healthy balance.

Other Minerals

Calcium. Calcium supplements may be important in older patients with diabetes to help reduce the risk for osteoporosis, particularly if their diets are low in dairy products.

Potassium. Evidence now strongly indicates that a potassium-rich diet can help achieve healthy blood pressure levels, and that potassium supplements can lower systolic blood pressure by 1.8 m Hg and diastolic blood pressure by 1 mm Hg. In fact, there is some evidence that a potassium-rich diet can reduce the risk of stroke by 22% to 40%. Current expert guidelines now support the use of potassium supplements or enough dietary potassium to achieve 3,500 mg per day for people with normal or high blood pressure (who have no risk factors for excess potassium levels). This goal is particularly important in people who have high sodium intake. The best source of potassium is from the fruits and vegetables that contain them. Some potassium-rich foods include bananas, oranges, pears, prunes, cantaloupes, tomatoes, dried peas and beans, nuts, potatoes, and avocados.

Of note, in this regard, certain kidney problems can cause potassium overload. Medications commonly used in diabetes, such as ACE inhibitors or potassium-sparing diuretics, also limit the kidney's ability to excrete potassium. No one should take potassium supplements without consulting a physician. The best source of potassium is from the fruits and vegetables that contain them.

Magnesium. Magnesium deficiency may have some role in insulin resistance and high blood pressure. One study reported that low magnesium levels as measured in blood tests were associated with a higher risk for type 2 diabetes in whites but not in African Americans. Dietary intake of magnesium, however, did not appear to play any role in increasing or reducing risk for either population group. It is more likely that diabetes may cause magnesium loss. A major 2001 study on diet found no effect on blood pressure from magnesium intake from foods. No supplements are recommended at this time for patients with adequate levels of magnesium. The recommended daily allowance is 320 mg. Persons who live in soft water areas, who use diuretics, or who have other risk factors for magnesium loss or ectopic beats may require more dietary magnesium than would others.

Chromium. Some studies have reported an association between deficiencies in the mineral chromium and a higher risk for type 2 diabetes. Studies on fat rats that were given chromium reported improvement in insulin sensitivity and glucose metabolism. Most studies on type 2 patients, however, reported little or no effect on glucose metabolism and some even reported adverse side effects.

Zinc. Many type 2 diabetics are also deficient in zinc; more studies are needed to establish the benefits or risks of taking supplements. Zinc has some toxic side effects, and some studies have associated high zinc intake with prostate cancer.

Fluids: Water, Caffeine, and Alcohol

Water. Many heart risk factors, especially those associated with blood clotting, are elevated with dehydration. In an interesting 2002 study, drinking five or more glasses of water a day was significantly associated with a lower risk for fatal heart events than drinking two or fewer glasses a day. More research is warranted on this simple way of protecting health. (Other fluids, including caffeinated and sugared drinks, were not protective.)

Alcohol. A number of studies have found protection from heart disease and type 2 diabetes with light to moderate intake of any type of alcohol. Some research suggests that alcohol has anti-inflammatory properties that protect arteries from injury. Red wine in particular may have specific benefits for people with type 2 diabetes. It has strong anti-oxidant effects that benefit the heart. Some evidence also suggests that red wine may improve insulin sensitivity and reduce blood glucose levels and may even protect against type 2 diabetes. Note: In those taking insulin or sulfonylureas, however, alcohol may cause a hypoglycemic reaction, of which the drinker may not be aware. Women who are pregnant or at risk for breast cancer and anyone at risk for alcohol abuse should not drink alcohol.

Tea. Although it contains caffeine, tea, both black and green, is often cited for its health benefits. Green tea is especially is rich in chemicals that offer protection against damaging forms of LDL. In one study, for example, higher intake, particularly by women, was associated with a lower risk for severe coronary artery disease. Black tea has also been associated with heart health. In one study oolong tea, a partially fermented tea, was specifically associated with lower blood sugar levels in type 2 diabetics.

Coffee. Coffee, like red wine, contains phenol, which helps prevent oxidation of LDL cholesterol. Studies are finding no association between coffee consumption and fatal or nonfatal heart disease even after 10 years. In fact, in one study the highest rates of fatal heart disease were in non-coffee drinkers, and women who increased their coffee intake reduced their mortality rates. On the downside, unfiltered coffee (Turkish coffee, Scandinavian boiled or French pressed coffee, and espresso) contains an alcohol called cafestol, which may raise cholesterol and triglyceride levels. Filtered coffee does not contain this residue. Coffee drinking is associated with small increases in blood pressure, but the risk it poses is very small in people with normal blood pressure. People with existing hypertension should avoid caffeine altogether.

Of note, caffeine has specific effects on insulin and glucose that may have an effect on people with diabetes, but the consequences are not clear. Some studies suggest that drinking large amounts of coffee may protect against diabetes. On the other hand, other research indicates that caffeine may increase the risk for insulin resistance. Some studies have reported a spike in insulin after drinking caffeinated beverages, which can be dramatic in people who are overweight. Research is needed to clarify the effects of caffeine on diabetes. In any case, caffeine intake can affect a person's awareness of hypoglycemia, since it reduces blood flow in the brain even in the presence of sufficient blood sugar. People with diabetes who drink even two or three cups of coffee may even believe they are hypoglycemic when their blood glucose levels are normal. On the positive side, coffee intake may increase awareness of hypoglycemia in some people who have difficulty recognizing its symptoms.