TUESDAY, June 13, 2006 (HealthDay News) -- Wondering if you're going to develop diabetes in your lifetime? Spend a minute on the bathroom scale: According to new research, your weight can provide a good indication of your future risk.
Nearly three out of four morbidly obese 18-year-old men, for example, will develop type 2 diabetes in their lifetime. And 35 percent of 18-year-old women who are simply overweight will contract the disease.
"This is the first time we were able to collect the type of data needed for these observations," said study author Dr. K.M. Venkat Narayan, chief epidemiologist at the U.S. Centers for Disease Control and Prevention. The research "can help us to know where to focus our attention."
Narayan's report is one of several studies into diabetes risk factors that are being released at the American Diabetes Association's annual scientific sessions, in Washington, D.C.
In the Narayan study, researchers examined the results of a national survey of almost 800,000 U.S. adults completed between 1997 and 2004. The researchers wanted to find out how body mass index (BMI) -- a ratio of weight to height -- translates into diabetes risk.
According to the study, an obese man with a BMI around 30 -- say, a 6-foot-tall man who weighs 225 pounds -- has a 57 percent chance of developing type 2 diabetes. A woman with the same BMI -- say, weighing 190 at 5-feet, 6-inches -- has a 55 percent chance.
By contrast, just 20 percent and 17 percent of 18-year-old men and women of normal weight, respectively, are expected to develop type 2 diabetes, the study found.
"The message here is, compared to a person with normal weight, a person who is overweight or obese at age 18 has a substantially higher chance of developing diabetes during his or her lifetime," Narayan said.
Among people aged 65 and older, "the additional risk of being overweight added a bit of extra risk, but not so much," Narayan said. "It's a very different situation from an 18-year-old who's overweight."
But older people who are obese had a "substantially higher" risk of type 2 diabetes than those who weighed less, Narayan said.
Why are overweight people at risk of diabetes? The reasons aren't clear, but they appear to have something to do with how fat disrupts the ability of cells to work with the hormone insulin, which helps convert blood sugar into energy for the body, Narayan said.
An estimated 19 million Americans have type 2 diabetes, and studies suggest that one-third of adults with the disease don't even know they have it. If left untreated, the disease can lead to complications such as heart disease, stroke, blindness, kidney disease, nerve problems, and foot or limb amputation.
Being overweight is thought to be a key risk factor for the disease.
Dr. Robert J. Rushakoff, an associate clinical professor of medicine at the University of California, San Francisco, said the study findings are "alarming" but valuable to doctors.
"Since prevention is so important, physicians and other health-care providers can make use of these dramatic numbers to talk to patients and try to start a move to better diet and exercise," he said.
In another study released at the diabetes meeting, Swedish researchers have linked three gene variants to type 2 diabetes. People with two or more of the variations have the highest risk of the disease. But, the researchers added, it's too early to predict for sure if someone will develop the disease.
To check your body mass index, visit the U.S. National Heart, Lung, and Blood Institute.