Persons with type 2 diabetes who had a diet high in low-glycemic foods such as nuts, beans and lentils had greater improvement in glycemic control and risk factors for coronary heart disease than persons on a diet with an emphasis on high-cereal fiber, according to a study in the December 17, 2008 issue of JAMA.

David J. A. Jenkins, M.D., of St. Michael's Hospital and the University of Toronto, and colleagues assessed the effects of a low-glycemic index diet vs. a high-cereal fiber diet on glycemic control and cardiovascular risk factors for 210 patients with type 2 diabetes. The participants, who were treated with antihyperglycemic medications, were randomly assigned to receive 1 of the 2 diet treatments for 6 months.

In the low-glycemic index diet, the following foods were emphasized: beans, peas, lentils, nuts, pasta, rice boiled briefly and low-glycemic index breads (including pumpernickel, rye pita, and quinoa and flaxseed) and breakfast cereals (including large flake oatmeal and oat bran). In the high-cereal fiber diet, participants were advised to take the "brown" option (whole grain breads; whole grain breakfast cereals; brown rice; potatoes with skins; and whole wheat bread, crackers, and breakfast cereals). Three servings of fruit and five servings of vegetables were encouraged on both treatments.

The researchers found that hemoglobin A1c (HbA1c; a substance of red blood cells tested to measure the blood glucose level) decreased by -0.50 percent absolute HbA1c units in the low-glycemic index diet compared with -0.18 percent absolute HbA1c units in the high-cereal fiber diet. Significant treatment effects were observed for high-density lipoprotein cholesterol (HDL-C) and the low-density lipoprotein cholesterol (LDL-C):HDL-C ratio. HDL-C increased in the low-glycemic index diet group by 1.7 mg/dL and decreased by -0.2 mg/dL in the high-cereal fiber diet group. The LDL-C:HDL-C ratio showed a greater reduction in the low-glycemic index diet group compared with the high-cereal fiber diet group.

"Lowering the glycemic index of the diet improved glycemic control and risk factors for coronary heart disease (CHD). These data have important implications for the treatment of diabetes where the goal has been tight glycemic control to avoid complications. The reduction in HbA1c was modest, but we think it has clinical relevance," the authors write. "Low-glycemic index diets may be useful as part of the strategy to improve glycemic control in patients with type 2 diabetes taking antihyperglycemic medications."

"Pharmacological interventions to improve glycemic control in type 2 diabetes have often failed to show a significant reduction in cardiovascular events. In view of the 2- to 4-fold increase in CHD risk in participants with type 2 diabetes, the ability of a low-glycemic index diet to address both glycemic control and CHD risk factors increases the clinical relevance of this approach for patients with type 2 diabetes, such as those in this study, who are overweight and also taking statins for CHD risk reduction."

(Reference JAMA. 2008;300[23]:2742-2753)

About Type 2 Diabetes

Type 2 diabetes is also referred to as non-insulin dependent diabetes mellitus (NIDDM), or adult onset diabetes mellitus (AODM). Type 2 diabetes affects nearly 21 million in the United States and nearly 200 million people worldwide.

Type 2 diabetes is characterized by high levels of blood sugar, caused by the body's inability to utilize insulin to move blood sugar into the cells for energy. In type 2 diabetes, patients can still produce insulin, but do so relatively inadequately for their body's needs, particularly in the face of insulin resistance as discussed above. In many cases this actually means the pancreas produces larger than normal quantities of insulin.

Diabetes is a major cause of heart disease and stroke, as well as the most common cause of blindness, kidney failure and amputations in U.S. adults. 

About Heart Disease

• Arrhythmias. Irregular, or abnormally fast or slow, beating of the heart. The heart beat is controlled by electrical impulses. When the timing or frequency of these electrical impulses are disrupted, arrhythmias develop. Some arrhythmias are quite serious. An example is ventricular fibrillation, a severely abnormal heart rhythm that causes death unless treated right away by providing an electrical shock to the heart (called defibrillation). Others are less severe but can develop into more serious conditions over time. A particular concern is atrial fibrillation. Atrial fibrillation is rapid, irregular beating of the upper chambers of the heart. The chambers can quiver instead of beating in a regular pattern. Blood is not fully pumped out of them and may pool and clot.
• Cardiomyopathy. A weakening of the heart muscle or a change in heart muscle structure. It often results in inadequate heart pumping or other heart function abnormalities. These can result from various causes, including prior heart attacks, viral or bacterial infections, and others.
• Congenital Heart Disease. Malformations of heart structures, present during pregnancy or at birth. These may be caused by genetic factors or by adverse exposures during pregnancy. Examples include holes in the walls that divide the heart chambers, abnormal heart valves, and others. Congenital heart defects can disrupt the normal flow of blood through the heart. Congenital heart defects are the most common type of major birth defect.
• Coronary Heart Disease (CHD)/ Coronary ArteryDisease (CAD). Coronary arterydisease (CAD), also called coronary heart disease (CHD) is a narrowing of the small blood vessels that supply blood and oxygen to the heart. CAD is the most common type of heart disease. CAD is the leading cause of death in the United States for men and women. According to the American Heart Association, more than 15 million people have some form of the condition. Coronary artery disease is caused by any problem with the coronary arteries that keeps the heart from getting enough oxygen- and nutrient-rich blood. The most common cause is atherosclerosis which occurs when fatty material and a substance called plaque builds up on the walls of your arteries. This causes them to get narrow. As the coronary arteries narrow, blood flow to the heart can slow down or stop The lack of sufficient blood is called ischemia, so coronary artery disease is sometimes called ischemic heart disease. The lack of blood flow can cause chest pain (stable angina), shortness of breath, irregular heart beats, called arrhythmias, and other symptoms. Over time, CAD can weaken the heart muscle and lead to heart failure, a serious problem where the heart cannot pump blood the way that it should.
• Heart Attack. A heart attack, also called a myocardial infarction may occur when blood supply to the heart is severely reduced or completely blocked. When blood flow is restricted the heart muscle cells do not receive enough oxygen and begin to die. The more time that passes without treatment to restore blood flow, the greater the damage to the heart. This damage can cause irregular heart rhythms or even sudden cardiac arrest or stopping of the heart beat. Death can result. Coronary artery disease is the chief underlying cause of a heart attack. A less common cause of a heart attack is a severe spasm of a coronary artery that reduces the blood supply to the heart.
• Heart Failure. This may also be called congestive heart failure or chronic heart failure. Heart failure is a condition where the heart cannot pump enough blood and oxygen to meet the needs of other body organs. Heart failure does not mean that the heart has stopped, but that it cannot pump blood the way that it should. Heart failure is a serious condition. There is no cure for heart failure at this time, except a heart transplant. Once diagnosed, medicines are needed for the rest of the person's life. See our heart failure fact sheet.
• Peripheral Arterial Disease (PAD). Hardening of the arteries that supply blood to the arms and legs. PAD is usually the result of atherosclerosis, the buildup of plaque and narrowing of the arteries. Blood flow and oxygen to the muscles in the arms and legs can be reduced or even fully blocked. Painful leg muscles, numbness, swelling in the ankles and feet, and weak pulse in the feet are some of the signs and symptoms of PAD.
• Rheumatic Heart Disease. This condition is damage to the heart valves and other heart structures due to inflammation and scarring caused by rheumatic fever, which occurs from streptococcal infection. Heart disease is an umbrella term for a number of different diseases affecting the heart. Heart disease is a number of abnormal conditions affecting the heart and the blood vessels in the heart.