America’s obesity epidemic is definitely driving the nation’s type 2 diabetes epidemic, says a new study by the U.S. Centers for Disease Control and Prevention.
While other factors play some role in the rapidly increasing number of people with diabetes, obesity is the major factor in the trend, said Linda S. Geiss, lead author of the study, published in the May issue of the American Journal of Preventive Medicine.
The study, based on concrete numbers drawn from the entire country, backs up what experts have long believed, said Geiss, a statistician with the CDC’s Division of Diabetes Translation.
“Most incidence studies [of diabetes] have been done on samples that aren’t representative of the United States,” she said. “These [new] data are nationally representative. And these data certainly help make the case that obesity is a major factor in the diabetes epidemic. I think it adds to the evidence.”
Geiss and her research team looked at statistics from the National Health Interview Survey, an ongoing nationwide in-person survey of about 40,000 households. They zeroed in on the years 1997 to 2003 to look for trends in the incidence of diagnosed diabetes in adults aged 18 to 79. Each year, about 31,000 adults were asked whether a health professional had told them they had diabetes. Not included was gestational diabetes, a type that occurs during pregnancy.
Participants were asked how old they were when their diabetes was diagnosed. The researchers had access to information about height and weight so they could compute the participants’ body mass index (BMI, a ratio of height to weight). A BMI of 25 and above is termed overweight; 30 and higher is considered obese.
Excess weight and inactivity are risk factors for type 2 diabetes, in which the body doesn’t properly use the hormone insulin, which is crucial for converting sugars and starches in the blood into fuel for the body.
The incidence of diagnosed diabetes rose 41 percent from 1997 to 2003 among the study participants, Geiss found.
About 20 million Americans have diabetes, although many do not yet know it, according to the American Diabetes Association.
About two-thirds of American adults are now overweight or obese, according to the National Institutes of Health. In 1960, 13 percent of adults were obese, but by 2000, nearly 31 percent were.
Geiss wanted to determine, however, if the rise in diabetes might be due at least partially to better detection methods allowing for earlier diagnosis. “If we were doing a better job, we would be detecting it earlier and when people are healthier.”
But from 1997 to 2003, those diagnosed with diabetes were not healthier or younger. Increased detection of diabetes “could be part of the answer,” she said, “but not the whole answer. It doesn’t seem to be a major factor. Most of the increase in diabetes occurred in those with a BMI of 30 or above. In 2003, 59 percent of the newly diagnosed were at a BMI of 30 or above. Another 30 percent were overweight, with a BMI of 25 to under 30. All together, 89 percent of the [new] cases were either overweight or obese.”
The study findings will not surprise experts, said Mary Austin, a diabetes educator and a researcher at Henry Ford Health System in Detroit, and part of the ACCORD (Action to Control Cardiovascular Risk in Diabetes) study.
“These findings are very reflective of what we see around the world,” Austin said. “The rise in weight and obesity is being seen globally,” she said, and with it, more type 2 diabetes is being diagnosed.
Her Advice? Know your risks and do something about them. “If you are not at your ideal body weight and are not active, over time, you have a risk of diabetes,” Austin said.
The oft-repeated message holds here, she said. Keep your weight at a healthy level and get regular, moderate exercise.
Geiss added: “Recent studies have shown we can prevent diabetes in those with risk factors, just with moderate lifestyle changes. Those include cutting down on daily calories for weight loss, if necessary, and getting activity into each day.”