Secular changes in U.S. Prediabetes prevalence defined by hemoglobin A1c and fasting plasma glucose: National Health and Nutrition Examination Surveys, 1999-2010

Abstract

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.

Figure 1

Cumulative distributions of A1C and fasting plasma glucose values for the U.S. population aged ≥12 years without diabetes for each survey cycle: 1999–2000, 2001–2002, 2003–2004, 2005–2006, 2007–2008, and 2009–2010. Estimates were weighted to the U.S. population. P value for equality of means was calculated from F test with five degrees of freedom (F₅). A1C units can be converted to mmol/mol using the equation: (10.93 × A1C) – 23.50.