Diabetes Rates in the US Have Finally Plateaued

Miriam E. Tucker

September 23, 2014

Diabetes rates among adults in the United States are finally leveling off, new data from the Centers for Disease Control and Prevention suggest.

The findings from the National Health Interview Survey (NHIS) on both prevalence and incidence of diabetes from 1980 to 2012 were published online September 23, 2014 in the Journal of the American Medical Association by Linda S. Geiss, section chief of diabetes surveillance at the Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, and colleagues.

"There's been a lot of good news lately in terms of rates of complications decreasing…but this is the first time we've been able to detect a change in the incidence of diabetes in a good way," Ms. Geiss told Medscape Medical News.

However, she cautioned that since diabetes had been increasing so dramatically prior to 2008, the year the plateau began, it's going to remain a huge problem for some time.

"It's not disappearing, it's leveled off....We need to continue all our efforts to help combat it, to prevent the complications of diabetes in those who have the disease, and to prevent diabetes itself."

Moreover, diabetes incidence has not abated among black and Hispanic adults, nor among younger adults and those without a high school education. "There are sociodemographic disparities. We can help tailor our prevention efforts to those at greatest risk," Ms. Geiss said.

She added, "It's certainly important for physicians to recommend lifestyle intervention programs to their patients at high risk. We know that these work and can help prevent diabetes."

The CDC's Diabetes Prevention Program website includes a listing of local programs where patients can be referred.

Sociodemographic Differences Evident

Ms. Geiss and colleagues estimated diabetes incidence and prevalence from among 664,969 adults aged 20 to 79 years who responded to questions about diabetes in the NHIS in 1980–2012.

Overall, the age-adjusted prevalence of diabetes (types 1 and 2 combined) was 3.5% in 1990, 7.9% in 2008, and 8.3% in 2012. The age-adjusted incidence per 1000 people was 3.2 in 1990, 8.8 in 2008, and 7.1 in 2012.

The annual percentage change was not significant during the 1980s (prevalence rose just 0.2% and incidence declined 0.1%). However, prevalence and incidence jumped from 1990 to 2008, with annual increases of 4.5% and 4.7%, respectively (P < .001 for both).

From 2008 to 2012, those changes diminished to a mere 0.6% per year increase in prevalence and a 5.4% drop in incidence (P = .64 and .09, respectively).

However, both diabetes incidence and prevalence continued to increase at a significantly greater rate for young adults aged 20 to 44 years compared with older adults and for black and Hispanic adults compared with white adults.

The rate of increase in prevalence was higher for those with a high school education or less compared with those with more than a high school education.

Is It All About Obesity?

An adjustment controlling for both age and body mass index (BMI) reduced the annual percent change in incidence by about a third (to 3.2%), while adjustment for other risk factors such as race/ethnicity and education had no effect.

This suggests that the leveling off of obesity that occurred over roughly the same time period explains a large part of the diabetes plateau, but not all of it, Ms. Geiss told Medscape Medical News.

She noted that the BMIs in the NHIS are self-reported and therefore most likely underestimated. Moreover, the data didn't include waist circumference, visceral adiposity, or other measures of obesity.

Beyond obesity, other possible influences on the reduction in diabetes rates include improvements in diet and activity levels and changes in the diagnostic criteria.

The 1997 lowering of the fasting plasma glucose cutoff from 140 mg/dL to 126 mg/dL may have increased the diabetes incidence, while the more recent shift to use of HbA1c for diagnosis may have reduced it, since HbA1c detects fewer cases of hyperglycemia, Ms. Geiss noted.

She pointed out that if the leveling off of diabetes is mostly due to the change in diagnostic criteria, "it should be a time-limited event, and diabetes would start going up again, like a market correction.…In future years we may be able to tease that out."

In any case, she told Medscape Medical News, "Diabetes is going to remain a major public-health problem and a major medical one to deal with. We have a lot of people now and will continue to have people who need help in the management of their disease. We will need to continue our strategies to prevent diabetes."

Ms. Geiss has reported no relevant financial relationships.

JAMA.Published online September 23, 2014. Abstract

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