More Americans than ever have diabetes, but counter efforts are starting to work

The prevalence of diabetes continues to increase in the U.S. in all subgroups and at all levels, according to new estimates. As many as half of all adult Americans now have diabetes or pre-diabetes.

Although diabetes has increased among all Americans in recent years, there is also a ray of hope—the proportion of Americans with undiagnosed diabetes has significantly decreased (along with an increase in diagnosed diabetes), which indicates that education efforts and diagnostic improvements are beginning to work, according to a study published September 8, 2015 in JAMA.

In this analysis, researchers used data from the National Health and Nutrition Examination Survey (NHANES) to estimate prevalence and trends in diabetes and undiagnosed diabetes. They defined diabetes using a previous diagnosis or, if diabetes was not previously diagnosed, by a hemoglobin A1c level of 6.5% or greater, a fasting plasma glucose (FPG) level of 126 mg/dL or greater, or a 2-hour plasma glucose (2-hour PG) level of 200 mg/dL or greater. Prediabetes was also defined with certain levels of these markers.

Notable findings included:

• The prevalence of diabetes increased significantly between 1988-1994 and 2011-2012 among the overall population, as well as in every age group, every racial/ethnic group, every education level, every income level, and in both sexes.
• The unadjusted prevalence (using the hemoglobin A1c, FPG, or 2-hour PG definitions for diabetes) was 14.3% for total diabetes, which included 9.1% for diagnosed diabetes and 5.2% for undiagnosed diabetes. That is, among all those with diabetes, 36.4% were undiagnosed.
• The unadjusted prevalence of total diabetes was higher in those aged 65 years or older (33.0%) compared with those aged 45-64 years (17.5%) and those aged 44 years or younger (5%).
• The age-standardized prevalence of diabetes was higher in African Americans (21.8%), Asians (20.6%), and Hispanics (22.6%) compared with whites (11.3%).
• The proportion of Americans with undiagnosed diabetes significantly decreased from 40.3% in 1988-1994 to 31.0% in 2011-2012. Still, percentages of undiagnosed cases were higher among Asians (50.9%) and Hispanics (49%) than all other racial/ethnic groups.
• For prediabetes, the unadjusted prevalence was 38% overall. The prevalence of prediabetes was greater than 30% in all sex and racial/ethnic categories, but generally highest among African Americans (39.6%) and whites (39.1%). The unadjusted prevalence of prediabetes was higher in participants aged 65 years or older (49.5%) and 45-64 years of age (44.9%) compared with those 44 years or younger (28.2%).
• The age-standardized mean body-mass index (BMI) was higher among African Americans participants (30.8), Hispanic participants (29.7), and white participants (28.4) compared with Asian participants (24.6).

“To our knowledge, our study provides the first estimates of the prevalence of total diabetes, undiagnosed diabetes, and prediabetes among Asian participants in the United States. More than half of non-Hispanic Asian participants had not been previously diagnosed and therefore were not aware of having diabetes,” wrote first author Andy Menke, PhD, of Social & Scientific Systems in Silver Spring, MD, senior author Catherine C. Cowie, PhD, of the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, MD, and colleagues. “In all, 10.6% of non-Hispanic Asian participants were estimated to have had undiagnosed diabetes using the hemoglobin A1c, FPG, or 2-hour PG definition, which was higher than any other racial/ethnic group. This may partly be due to less frequent screening for diabetes because non-Hispanic Asian individuals on average have lower BMIs.”

An accompanying editorial in JAMA noted that, “Multifaceted approaches addressing both environmental factors and individual behaviors appear to be slowing the increase in obesity and diabetes, and facilitating the diagnosis and management of diabetes,” wrote William H. Herman, MD, MPH, and Amy E. Rothberg, MD, PhD, of the University of Michigan Health System, Ann Arbor, MI. “Progress has been made, but expanded and sustained efforts will be required.”