Research Reveals New Ways to Fight Diabetes


RECENT RESEARCH is giving new clues about how to attack diabetes — the fifth leading killer of Americans, responsible for 73,000 deaths a year. We already know that lifestyle changes can help prevent type 2 diabetes (the form that develops later in life). According to the American Diabetes Association, just 30 minutes a day of moderate physical activity, coupled with a 5-10% reduction in body weight, can cut your risk of diabetes by 58%. But now new studies have added to the diabetes-prevention picture: Depending on their form, carbohydrates may raise or lower your risk. And getting enough sleep and eschewing cigarettes — a good idea anyway for your health — may also help reduce your risk for diabetes.

The Carb Connection
Experts remain uncertain regarding exactly how diet, including carbohydrate intake, affects the development of type 2 diabetes. But research indicates that the body absorbs carbohydrates from different foods at different rates, leading to varying effects on levels of blood glucose and insulin. Simple carbohydrate foods — such as white rice, white bread and refined sugar — score high on the glycemic index; these foods cause a rapid spike and then a drop in blood glucose. High-fiber foods — the "complex" carbohydrates, like whole grains — are lower on the glycemic index and have a more gradual effect on blood sugar and insulin.

A pair of new studies, published in the same issue of Archives of Internal Medicine, support a link between eating foods high in the glycemic index and increased risk for developing type 2 diabetes, particularly in some women.

One study, led by Wei Zheng, MD, PhD, of Vanderbilt Epidemiology Center, followed a group of 64,227 middle-aged Chinese women for an average of five years. Zheng and colleagues collected data on dietary habits, physical activity and other health-related information through semi-annual in-person interviews. One reason for focusing on this particular population was that Chinese traditionally consume a lot of high-glycemic carbohydrates, particularly white rice.

During the course of the study, 1,608 of the Chinese women developed diabetes. Women who consumed the most carbohydrates overall were more likely to develop diabetes. When subjects were split into five groups based on carbohydrate intake, those in the group consuming the most — about 338 grams, or 12 ounces, per day — had a 28% higher risk for diabetes than those in the group consuming the least (about 264 grams, or 9.3 ounces, per day).

Women who ate diets with a higher glycemic index, and those who ate more staples such as bread, noodles and rice specifically, also had an increased risk. Women who ate 300 grams (10.6 ounces) or more of rice per day were 78% more likely to develop diabetes than those who ate less than 200 grams daily. At least in this population, first author Raquel Villegas, PhD, and colleagues concluded, "High intake of foods with a high glycemic index and glycemic load, especially rice, the main carbohydrate-contributing food in this population, may increase the risk of type 2 diabetes."

In the second study, Supriya Krishnan, DSc, of Boston University Slone Epidemiological Center, and colleagues examined data from the Black Women's Health Study, a prospective cohort study of 59,000 US black women. At the study's start in 1995, participants filled out food questionnaires, from which researchers calculated the women's glycemic index and glycemic load (a ranking of carbohydrate content in food based on glycemic index and portion size).

Semi-annually for the next eight years, the women answered follow-up questionnaires about their weight, health and other factors. Over that time, 1,938 participants developed type 2 diabetes. The women who ate the most high-glycemic-index foods had a higher risk for diabetes, with the one-fifth at the highest end of the glycemic-index spectrum 23% more likely to develop the disease than those in the lowest group. '

Because high-glycemic index foods abruptly and significantly increase blood glucose levels, they increase the body's demand for insulin. This may contribute to problems with the pancreas — the organ that produces insulin — eventually leading to diabetes, the authors speculated.

But this study also found good news beyond a general recommendation to cut back on high-glycemic-index foods. The women who ate the most fiber from grains (cereal fiber) were 18% less likely to develop diabetes.

"Our results indicate that black women can reduce their risk of diabetes by eating a diet that is high in cereal fiber," Krishnan and colleagues wrote. The researchers went on to give clear dietary suggestions: "Incorporating fiber sources into the diet is relatively easy: a simple change from white bread (two slices provides 1.2 grams of fiber) to whole wheat bread (two slices provides 3.8 grams of fiber) or substituting a cup of raisin bran (5 to 8 grams of fiber) or oatmeal (4 grams of fiber) for a cup of Corn Chex (0.5 grams of fiber) or Rice Chex (0.3 grams of fiber) will move a person from a low fiber intake category to a moderate intake category, with a corresponding 10% reduction in risk."

Pillow Talk
A dietary connection with diabetes risk is easy to understand — but sleep? A new study suggests that getting too little shuteye may increase your risk of diabetes.

Researchers found that sleeping an average of five hours or less increased the odds for diabetes onset by about 50% compared with those who got seven hours of sleep. That association held even after controlling for more conventional risks, such as older age and higher body mass index (BMI). James E. Gangwisch, PhD, of Columbia University, and colleagues reported their findings in the journal Sleep. The findings are consistent, the authors said, with evidence suggesting that short sleep duration increases insulin resistance and decreases glucose tolerance.

To examine the link between sleep duration and diabetes, the researchers analyzed data from the first National Health and Nutrition Examination Survey (NHANES I), which followed 8,992 non-institutionalized persons ages 32 to 86 for 10 years. Nearly 5% of the NHANES I subjects developed diabetes during that follow-up period.

The researchers also found that sleeping an average of nine hours or more was associated with increased risk of being diagnosed with diabetes. This association between diabetes and longer sleep duration, however, eluded explanation.

"We are not aware of any plausible physiologic explanations whereby long sleep duration could play a role in the pathogenesis of diabetes," Gangwisch and colleagues concluded.

They did suggest a possible connection between sleep duration, diabetes and other conditions associated with chronic inflammation. Scientists have long suspected that inflammation is linked to insulin resistance, which precedes nearly all cases of type 2 diabetes. In the early 1900s, diabetics were sometimes given high doses of aspirin, which is an antiinflammatory.

Snuff Out Extra Risk
Adding to a long list of health hazards associated with smoking, a new meta-analysis of 25 previous studies totaling more than 1.2 million participants concluded that smoking may also be risk factor for type 2 diabetes. William A. Ghali, MD, MPH, of the University of Calgary, and colleagues found smoking associated with a 44% increase in the risk of diabetes. The risk appeared greatest for heavy smokers. The good news is that smoking is a risk factor people can change — by stopping the habit now! — and the diabetes risk dropped, in fact, for smokers in the analyzed studies who quit.

Dr. Ghali and colleagues, publishing their findings in the Journal for the American Medical Association, suggested that smoking may lead to insulin resistance and diabetes through a direct effect on the pancreas. "This could be due to a direct effect of nicotine or other components of cigarette smoke on beta cells of the pancreas, as suggested by the association of cigarette smoking with chronic pancreatitis and pancreatic cancer," they wrote. Smoking increases inflammation and oxidative stress, which can directly damage beta-cell function and impair endothelial function, factors strongly implicated in insulin resistance and, hence, diabetes risk.

Though the researchers cautioned their analysis did not prove smoking causes diabetes, they did note a "consistent finding of increased diabetes incidence associated with active cigarette smoking."

TO LEARN MORE: American Diabetes Association, (800) DIABETES (800-342-2383); 1701 N. Beauregard St., Alexandria, VA 22311; . Mites of Internal Medicine, Nov. 26,2007; abstracts at and . Sleep, December 2007; abstract at . Journal of the American Medical Association, Dec. 12,2007; abstract at .

A Diabetes Primer
Diabetes defined: Diabetes is a disease in which the body does not adequately produce or properly use insulin, a hormone that "unlocks" the cells of the body, allowing glucose to enter and fuel them. In the US, about 20.8 million children and adults-7% of the population — have diabetes. Of these, 14.6 million have been diagnosed with diabetes, while an estimated 6.2 million people have the disease yet are unaware of it.

Undiagnosed or untreated diabetes is a serious danger to health. When glucose builds up in the blood instead of going into cells, it can starve cells for energy; over time, high blood glucose levels can damage the eyes, kidneys, nerves or heart.

Diabetes takes two primary forms. Type 1 diabetes (previously known as "juvenile diabetes") is usually diagnosed in children and young adults. In type 1, the body does not produce insulin at all. Type 2, the "developed" form of the disease, is the most common form of diabetes. In type 2 diabetes, the body does not produce enough insulin while the body's cells ignore the insulin that is available, a condition called "insulin resistance."

Before people develop type 2 diabetes, they almost always have "pre-diabetes"- blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes. An estimated 54 million Americans have pre-diabetes.

Diagnosing the disease: To diagnose diabetes, health-care providers conduct a Fasting Plasma Glucose Test (FPG) or an Oral Glucose Tolerance Test (OGTT). With the FPG test, a fasting blood glucose level between 100 and 125 mg/dl signals pre-diabetes. A person with a fasting blood glucose level of 126 mg/dl or higher has diabetes.

In the OGTT test, a person's blood glucose level is measured after a fast and two hours after drinking a glucose-rich beverage. If the two-hour blood glucose level is between 140 and 199 mg/dl, it indicates pre-diabetes. If the two-hour blood glucose level is at 200 mg/dl or higher, the person tested has diabetes.

Are you at risk? Diabetes often goes undiagnosed because many of its symptoms seem so harmless. Recent studies indicate that the early detection of diabetes symptoms and treatment can lower your risk for the disease's debilitating complications. Some diabetes symptoms include:

Frequent urination
Excessive thirst
Extreme hunger
Unusual weight loss
Increased fatigue
Blurry vision

Both genetics and lifestyle factors such as obesity and lack of exercise appear to play roles in developing diabetes. If the disease-particularly type 2-runs in your family, if you have a sedentary lifestyle, or if you have some of the symptoms listed above, you may want to talk with your doctor about diabetes. The American Diabetes Association has a diabetes risk calculator on its Web site at .

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