Regular consumption of foods with a
high glycemic index appears to increase the risk of type
2 diabetes in African-American and Chinese women, according
to the results of two studies recently published.
Glycemic index refers to how rapidly a food causes blood
sugar to rise. High-glycemic
index foods, like white bread and potatoes, tend
to spur a quick surge in blood sugar, while low-glycemic
index foods, such as lentils, soybeans, yogurt
and many high-fiber grains, create a more gradual increase
in blood sugar.
For their study, Dr. Supriya Krishnan, from Boston University
School of Public Health, and colleagues examined data
from 40,078 U.S. black women who filled out a food questionnaire
in 1995. The glycemic index and glycemic load were calculated.
Every two years through 2003, the women provided up-to-date
information about their weight, health and other factors.
During 8 years of follow-up, 1,938 women developed diabetes.
Results showed that women who ate high-glycemic
index foods or a diet with a high glycemic load
had a higher risk for diabetes. However, women who ate
more fiber from grains (cereal fiber) had a reduced risk.
"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 write. "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 percent reduction in risk."
In the other study, Dr. Raquel Villegas, from Vanderbilt
University Medical Center in Nashville,
Tennessee, and colleagues followed a group of 64,227
Chinese women for an average of five years. They interviewed
the women every two years between 2000 and 2004, to gather
health-related information such as dietary habits and
physical activity levels.
During follow-up, 1,608 women developed type 2 diabetes.
Results showed that women who consumed more carbohydrates
overall were more likely to develop diabetes. When they
were split into five groups based on carbohydrate intake,
those in the group consuming the most (about 337.6 grams
per day) had a 28 percent higher risk than those in the
group consuming the least (about 263.5 grams per day).
Women who had diets with a higher glycemic index and
who ate more staples such as bread, noodles and rice specifically
also had an increased risk. Women who ate 300 grams or
more of rice per day were 78 percent more likely to develop
diabetes than those who ate less than 200 grams per day.
"Given that a large part of the world's population
consumes rice and carbohydrates as the mainstay of their
diets, these prospective data linking intake of refined
carbohydrates to increased risk of type 2 diabetes mellitus
may have substantial implications for public health,"
Villegas' team concludes.
of Internal Medicine, November 26, 2007.