OBJECTIVE Using a nationally representative sample of the civilian noninstitutionalized U.S. population, we estimated prediabetes prevalence and its changes during 1999–2010.

RESEARCH DESIGN AND METHODS Data were from 19,182 nonpregnant individuals aged ≥12 years who participated in the 1999–2010 National Health and Nutrition Examination Surveys. We defined prediabetes as hemoglobin A1c (A1C) 5.7 to <6.5% (39 to <48 mmol/mol, A1C5.7) or fasting plasma glucose (FPG) 100 to <126 mg/dL (impaired fasting glucose [IFG]). We estimated the prevalence of prediabetes, A1C5.7, and IFG for 1999–2002, 2003–2006, and 2007–2010. We calculated estimates age-standardized to the 2000 U.S. census population and used logistic regression to compute estimates adjusted for age, sex, race/ethnicity, poverty-to-income ratio, and BMI. Participants with self-reported diabetes, A1C ≥6.5% (≥48 mmol/mol), or FPG ≥126 mg/dL were included.

RESULTS Among those aged ≥12 years, age-adjusted prediabetes prevalence increased from 27.4% (95% CI 25.1–29.7) in 1999–2002 to 34.1% (32.5–35.8) in 2007–2010. Among adults aged ≥18 years, the prevalence increased from 29.2% (26.8–31.8) to 36.2% (34.5–38.0). As single measures among individuals aged ≥12 years, A1C5.7 prevalence increased from 9.5% (8.4–10.8) to 17.8% (16.6–19.0), a relative increase of 87%, whereas IFG remained stable. These prevalence changes were similar among the total population, across subgroups, and after controlling for covariates.

CONCLUSIONS During 1999–2010, U.S. prediabetes prevalence increased because of increases in A1C5.7. Continuous monitoring of prediabetes is needed to identify, quantify, and characterize the population of high-risk individuals targeted for ongoing diabetes primary prevention efforts.

Diabetes is a major public health problem in the U.S., affecting 25.8 million people in 2011 (1). In addition, a condition known as prediabetes is associated with an increased risk of developing diabetes. An expert committee convened by the America Diabetes Association defined prediabetes as a fasting plasma glucose (FPG) level of 100 to 125 mg/dL (impaired fasting glucose [IFG]), a 2-h plasma glucose level after a 75-g oral glucose tolerance test of 140 to 199 mg/dL (impaired glucose tolerance [IGT]), or hemoglobin A1c (A1C) 5.7 to <6.5% (39 to <48 mmol/mol) (2). In 2010, 79 million U.S. adults had prediabetes based on IFG or elevated A1C criteria (1). Fortunately, the Diabetes Prevention Program of the National Institutes of Health and other studies have shown that among adults with elevated glucose levels, type 2 diabetes can be delayed or prevented (3–6). Further, recent studies have shown that effective lifestyle-based interventions can be successfully implemented in community-based settings (7–9), potentially reaching disparate populations (10–13). As the public health community seeks to address the urgent problem of diabetes prevention with broad implementation of proven measures, there is a strong need for reliable surveillance data to identify, measure, and characterize populations who could benefit from such interventions and help assess the effectiveness of prevention efforts.

Prediabetes prevalence estimates vary according to the type and combination of glycemic tests in use, the demographic characteristics of the population being measured, and other factors (14). Although increases in diagnosed and total diabetes in the U.S. are well documented, no increases in the prevalence of prediabetes have been detected (15). However, there have been several changes in the measurement of prediabetes since 2003, including changes in FPG criteria from 110 to 100 mg/dL and the introduction of A1C prediabetes cut points (16,17). Changes have also occurred in the demographic distribution of the U.S. population (18). To examine whether these changes may have been accompanied by corresponding changes in the prevalence of prediabetes, we estimated the prevalence of prediabetes in the U.S. for three time periods: 1999–2002, 2003–2006, and 2007–2010. We compared prevalence estimates obtained using two different measures of glycemic status—alone and combined—and obtained estimates for a range of subpopulations defined by sociodemographic and obesity status.