The circumference of a man's waist is a better
predictor of his risk of developing type 2 diabetes than
his body mass index, which is a weight-to-height ratio, or
waist-to-hip ratio alone.
This finding, published in the March issue of the
American Journal of Clinical Nutrition, is based on
data collected from 27,270 men tracked over 13 years who
participated in the Harvard Health Professionals Follow-Up
Men who had larger waists (assessed using waist
circumference and waist-hip ratio) or higher overall body
fat (indicated by body mass index, or BMI) had a greater
risk of developing type 2 diabetes.
The researchers divided the study participants into
five groups according to their waist size. Compared to
those in the group with the smallest waists (29-34 inches),
the other groups (34.3-35.9 inches, 36.0-37.8 inches,
37.9-39.8 inches, 40-62 inches) were two, three, five and
12 times more likely to develop diabetes, respectively.
Similarly, risk was two, three, four and seven times
greater when waist-hip ratio was measured in men and one,
two, three and eight times greater when BMI was
"Both BMI and waist circumference are useful tools to
assess health risk," said the study's lead author, Youfa
Wang, assistant professor with the
Center for Human
Nutrition at the Johns Hopkins Bloomberg School of
Public Health. "But abdominal fat measured by waist
circumference can indicate a strong risk for diabetes
whether or not a man is considered overweight or obese
according to his BMI."
The authors suggest that the currently recommended
waist circumference cutoff of 40 inches for men may need to
be lowered. "Many of the men who developed type 2 diabetes
had measurements lower than the cutoff," Wang said, "and
the risk associated with waist circumference increased at a
much lower level."
While nearly 80 percent of the men in this cohort who
developed type 2 diabetes could be identified using a BMI
of 25, the cutoff for overweight, only half (50.5 percent)
had a waist circumference greater than or equal to 40
inches, the cutoff recommended by the National Institutes
Men with waist circumference of 40 inches or greater
and who also fell into the obese category with a BMI of 30
or greater were at more than twice the risk to get type 2
diabetes as were those who had a high BMI or a high waist
circumference alone. In addition to measuring BMI, the
investigators recommend that physicians and researchers
measure waist circumference instead of the waist-to-hip
ratio because it is a better measure of central obesity for
predicting the risk of type 2 diabetes and is subject to
fewer measurement errors.
The study authors also urge that more research on this
topic be conducted with cohorts that include women and
different ethnic and racial groups, since the Health
Professionals Follow-Up Study involved only a cohort of
largely white, professional men, who are likely to be
healthier than the average American.
The study was written by Wang, Eric B. Rimm, Meir J.
Stampfer, Walter C. Willett and Frank B. Hu.
Information about the Johns Hopkins Center for Human
Nutrition is available at