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Study: Nearly 10% of U.S. Adults Have Diabetes

Disease affects 21 million people aged 20 years or older

The percentage of Americans with diabetes has nearly doubled since 1988, and about one in 10 adults is now diagnosed with the disease, according to a new study published in the Annals of Internal Medicine.

Researchers conducted a cross-sectional analysis of data from the National Health and Nutrition Examination Survey (NHANES) to determine trends in the prevalence of diabetes, prediabetes, and glycemic control in 1988–1994, 1999–2004, and 2005–2010. The study included more than 43,000 adults aged 20 years or older.

The investigators calibrated hemoglobin A1c (HbA1c) levels to define undiagnosed diabetes (≥ 6.5%); prediabetes (5.7% to 6.4%); and, among persons with diagnosed diabetes, glycemic control (< 7.0% or < 8.0%). Trends in HbA1c categories were compared with fasting glucose levels.

The authors found that, in 1988–1994, the prevalence of diagnosed diabetes was 5.5%. By the next survey, in 1999–2004, that number had risen to 7.6%. In the final survey, conducted from 2005 to 2010, the prevalence of diagnosed diabetes was 9.3%.

In the final assessment year (2010), approximately 21 million U.S. adults aged 20 years or older had confirmed diabetes (self-reported diabetes or diagnostic levels for both fasting glucose and calibrated HbA1c).

In contrast, the prevalence of undiagnosed diabetes remained fairly stable, reducing the proportion of total diabetes cases that were undiagnosed to 11% in 2005–2010.

The authors also found that levels of obesity increased throughout the study periods. In people without diabetes, obesity rates rose from about 21% in 1988–1994 to more than 32% in 2005–2010. In those with diabetes, nearly 44% were obese in 1988–1994, and that number increased to about 61% in 2005–2010.

The prevalence of prediabetes (defined by HbA1c levels) also increased dramatically, from 5.8% in 1988–1994 to 12.4% in 2005–2010.

Glycemic control improved overall, but total diabetes prevalence was greater and diabetes was less controlled among non-Hispanic blacks and Mexican Americans compared with non-Hispanic whites.

The authors concluded that, over the past 2 decades, the prevalence of diabetes has increased substantially in the U.S. However, the proportion of undiagnosed diabetes cases decreased, suggesting improvements in screening and diagnosis.

Sources: Annals of Internal Medicine; April 15, 2014; and Medical Xpress; April 15, 2014.

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