County-Level Data Reveal Three-Fold Difference in Diabetes Prevalence Across the U.S.

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Michelle Kirkwood
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Alexandria, Virginia
August 23, 2016

Data Includes Diagnosed, Undiagnosed and Total Diabetes Prevalence, as well as Rates of Successful Treatment and Awareness

A county-level analysis of diabetes data in the United States reveals wide variations in prevalence across the country, with a three-fold difference in prevalence among counties with the highest and lowest rates. The analysis also finds stark differences among rates of diagnosis, diabetes awareness and effective treatment, which could help policymakers and healthcare providers identify areas in need of greater public health resources. The analysis was published in Diabetes Care on August 23, 2016.

The analysis showed that total diabetes prevalence (including diagnosed and undiagnosed) ranged from 8.8 percent (Los Alamos County, NM) to 26.4 percent (Starr County, TX) of the population among American counties in 2012. Overall, counties in the deep South (excluding Florida), those close to the Mexican border in Texas, and counties with Native American reservations in the Four Corners region of the Southwest and in North and South Dakota, exhibited the highest prevalence. Prevalence was lowest in counties in the upper West and Midwest, parts of Alaska and parts of New England. Colorado, interestingly, was home to seven of the top 10 counties with the lowest prevalence.

Diabetes Prevalence 2016 Chart

"These results, detailing county-by-county trends, can play an important role in providing health care leaders and policymakers with a blueprint for communities demonstrating the greatest need for more effective diabetes prevention and treatment strategies," said Laura Dwyer-Lindgren, the paper's lead author and a researcher with the Institute for Health Metrics and Evaluation at the University of Washington in Seattle. "We hope our findings will be used to target high-burden areas and to help select the right mix of public health strategies for each community. This data empowers leaders at the local and national level to make dramatic improvements in public health."

The researchers analyzed 1999-2012 data from the National Health and Nutrition Examination Survey (NHANES), which combines interviews and physical exams held annually in 15 counties to determine the health and nutritional status of children and adults from, and the Behavioral Risk Factor Surveillance System (BRFSS), which uses telephone surveys conducted in every state to collect data about U.S. residents' health-related risk behaviors, chronic health conditions and use of preventive services.

Combining these data created a more complete picture of the burden of diabetes in each county and also allowed researchers to look at markers of how well the health system is responding to this burden, namely, rates of diagnosis and rates of successful treatment.

The analysis showed diagnosed diabetes prevalence for the nation as a whole was 10.2 percent in 2012, and undiagnosed diabetes prevalence was 4.1 percent, with a total diabetes prevalence of 14.3 percent of the population. At the county level, diagnosed diabetes prevalence ranged from 5.6 percent to 20.4 percent, whereas undiagnosed diabetes prevalence ranged from 3.2 percent to 6.8 percent.

Nationally, total diabetes prevalence rose by 40 percent from 1999 to 2012, from 10.2 percent to 14.3 percent of the population. Though prevalence increased among all counties, the rate of increase varied widely, from 18.9 percent to 72 percent. The increase in diagnosed diabetes showed an even wider variation among counties, from 25.2 percent to 117.1 percent. Nationally, the increase in prevalence was larger for diagnosed diabetes (56.8 percent) than for undiagnosed diabetes (10.3 percent).

Diabetes prevalence was higher among men than women both at the national level and in 95.1 percent of the counties analyzed. Diagnosed diabetes was only slightly higher among men than among women (10.6 percent vs. 9.9 percent), but undiagnosed diabetes was substantially higher (5.0 percent among men vs. 3.2 percent among women). Total diabetes prevalence was 15.6 percent among men vs. 13.0 percent among women.

Diabetes awareness also varied widely among counties, ranging from 59.1 percent to 79.8 percent of the population. Awareness was defined as the proportion of adults age 20 or older with a previous diabetes diagnosis and/or high FPG or A1C with a diagnosis (the ratio of diagnosed to total diabetes prevalence). Awareness increased 12 percent from 1999 to 2012, from 63.9 percent to 71.6 percent. During that same period, diabetes control rose only slightly, by 1.5 percent.

"The variation in total diabetes prevalence within the U.S. is staggering, with a threefold difference between the counties with the lowest prevalence and those with the highest prevalence," the researchers continued. "Given the significant health and financial burden of high diabetes prevalence, this disparity demands further investigation into what underlying (and potentially modifiable) factors drive the exceedingly high diagnosed and total diabetes rates found in many communities."

"Type 2 diabetes is both preventable and treatable," the researchers concluded. "The public health system has a role to play in increasing awareness of and screening for diabetes, connecting affected and high-risk individuals with appropriate medical care, and promoting community level interventions that address known risk factors such as poor diet or lack of physical activity. The results of this analysis should be considered by state and local health officials aiming to increase early detection and improve the health of impacted communities."

Copies of the full article are available online at http://care.diabetesjournals.org/content/current. Maps of county prevalence data are available upon request.

About the American Diabetes Association

More than 30 million Americans have diabetes, and every 21 seconds another person is diagnosed with diabetes. The American Diabetes Association (Association) is the global authority on diabetes and since 1940 has been committed to its mission to prevent and cure diabetes and to improve the lives of all people affected by diabetes. To tackle this global public health crisis, the Association drives discovery in research to treat, manage and prevent all types of diabetes, as well as to search for cures; raises voice to the urgency of the diabetes epidemic; and provides support and advocacy for people living with diabetes, those at risk of developing diabetes and the health care professionals who serve them. For more information, please call the American Diabetes Association at 1-800-DIABETESS (1-800-342-2383) or visit diabetes.org. Information from both of these sources is available in English and Spanish. Find us on Facebook (American Diabetes Association), Twitter (@AmDiabetesAssn) and Instagram (@AmDiabetesAssn)