By Brenda Goodman, MA
WebMD Health News
Reviewed by Brunilda Nazario, MD
Sept. 8, 2015 -- Half of Americans have diabetes or are well on their way to getting it, a new study estimates.
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As the U.S. population has grown older and heavier, the number of people who are having trouble controlling their blood sugar has climbed.
Two decades ago, about 1 in 10 adults had diabetes. Now, the number if closer to 1 in 7 or 8, or 12% to 14%.
Another 38% of people have blood sugar high enough to put them on the cusp of that diagnosis,a risk category doctors call prediabetes.
"Seeing these high rates of diabetes is quite concerning. I do really think we need a call to action, and we need to do a better job of preventing diabetes in the first place and preventing its complications," says Elizabeth Selvin, PhD, professor of epidemiology and medicine at the Johns Hopkins Bloomberg School of Public Health. In a study published last year, Selvin estimated similarly high rates of diabetes. She was not involved in the current study.
The new research also underscored the heavy toll the disease is taking on certain ethnic groups. African-Americans, Hispanics, and Asian-Americans were about twice as likely to have diabetes as whites. They were also more likely to go undiagnosed.
"Ethnic minority groups are at high risk for complications of diabetes, so the racial disparities and burden of diabetes and prediabetes are particularly concerning," Selvin says.
Researchers say while the numbers are high, there are some encouraging signs. Doctors are catching the disease more often. The proportion of people with undiagnosed diabetes appears to be dropping. And the overall prevalence of the disease seems to have been holding steady since about 2008.
An editorial running alongside the study cheered the findings, saying that they offer a glimmer of hope that public health efforts are turning the tide.
The study authors, though, think it's too early to celebrate.
"I'm not convinced that [the prevalence of diabetes] has plateaued. It's plateaued before," says Catherine C. Cowie, PhD, an epidemiologist and senior advisor at the National Institute of Diabetes, Digestive, and Kidney Diseases.
To estimate the new numbers, Cowie and her team plumbed the latest data gathered by the government's long running National Health and Nutrition Examination Survey.
People who volunteer for those surveys, which have run every 2 years since 1999, answer a battery of questions about their health, lifestyle, and diet in an in-home interview. They also visit a mobile clinic where blood and urine samples are taken.
Researchers looked at test results from the 2011-2012 cycle. And they checked three different measures -- fasting blood sugar, blood sugar taken 2 hours after people drank a syrupy glucose solution, and hemoglobin A1c, a blood marker that gauges average blood sugar levels over the last 2 to 3 months.
In the study, if any one of those were elevated, the person was counted as having diabetes or prediabetes. That probably overestimated the true number of people with blood sugar problems. (A diagnosis of diabetes is made when one of these tests is confirmed on a second occasion.)
Also, at least one of those tests -- fasting blood sugar -- has a high rate of false-positive results. Selvin says about 25% of those tests will read high, even though the person has normal blood sugar. Most doctors will repeat that test if they get one high result, something researchers didn't have the luxury of doing in the study.
Cowie admits that the study doesn't perfectly reflect how people would be diagnosed in the real world.
"This really is a full accounting. It's not necessarily what they do out in the medical community, but really, there's that number of people that have some sort of dysglycemia," or trouble regulating their blood sugar, she says.
Cowie says she hopes her study will motivate people to get their blood sugar checked, especially if they are overweight.
And she hopes people with prediabetes will use their diagnosis to take action before the disease sets in.
"You almost have to look at it as a good thing, because it's a window of opportunity. It allows you to decrease your risk for diabetes," Cowie says. "You can do that."
She says people with prediabetes should work hard to lose weight, get more physical activity, and should talk to their doctor about taking the medication metformin, which has been shown in a large government study to delay diabetes for 15 years.
SOURCES: Elizabeth Selvin, PhD, professor, epidemiology and medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore. Catherine C. Cowie, PhD, epidemiologist and senior advisor, National Institute of Diabetes, Digestive, and Kidney Diseases, Bethesda, MD. Cowie, C. Journal of the American Medical Association, Sept. 8, 2015.
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