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An Epidemic of Obesity Myths
Myth: Obesity Has Made Diabetes Epidemic

"...the prevalence of diabetes … did not appear to increase substantially during the 1990s."
-CDC's Morbidity and Mortality Weekly Report, 2003

Diabetes "epidemic" amounts to 0.4% increase
Adjusted percentage of adults aged >= 20 with fasting blood glucose levels above 126 mg/dL
NHANES III (1988-1994)  NHANES (1999-2000)  

According to the CDC:
"The twin epidemics of diabetes and obesity continue. From 1991 to 2001, a recent CDC study found a 61 percent increase in diagnosed diabetes (including gestational) in Americans and a 74 percent increase in obesity, reflecting the strong correlation between obesity and the development of diabetes."
But epidemiological research gathered, analyzed, and published by the CDC tells a very different story. According to the agency, data from its NHANES survey collected between 1988 and 2000 "indicate that the prevalence of diabetes, either diagnosed or undiagnosed, and impaired fasting glucose did not appear to increase substantially during the 1990s."

So what explains the discrepancy in the CDC's data?

The CDC employs two different methods of measuring the prevalence of diabetes. The first counts the number of self-reported cases of diabetes. The second uses data gathered from laboratory blood samples to count patients whose fasting glucose levels exceed 126 milligrams per deciliter (mg/dL) of blood-the diagnostic standard for epidemiological research. The CDC's 61-percent-increase estimate comes from the Behavioral Risk Factor Surveillance System and relies on the first method. The NHANES data—which show almost no increase in the prevalence of diabetes—come from the latter. According to CDC researchers:

"We are also reminded that, although several studies have reported higher rates of diagnosed diabetes in recent decades, the NHANES data are the only national data examining changes in total diabetes prevalence."
When determining which data to trust, it is important to keep in mind two factors that might make the NHANES estimate superior. First, NHANES accounts for a change in the standard by which diabetes is diagnosed. Second, it is not subject to bias based on increased awareness, and therefore increased diagnosis, of diabetes.

Wrong Before

A 2002 article by CDC researchers published in the American Journal of Public Health reported that "diabetes prevalence among the U.S. general population younger than 45 years increased by 14% between 1990 and 1996." Two months later, the team of researchers published a correction, noting that the increased prevalence among the population younger than 45 was just 3 percent.