Trends in the Prevalence and Ratio of Diagnosed to Undiagnosed Diabetes According to Obesity Levels in the U.S

Trends in the Prevalence and Ratio of Diagnosed to Undiagnosed Diabetes According to Obesity Levels in the U.S. Edward W. Gregg , PHD 1 , Betsy L. Cadwell , MSPH 1 , Yiling J. Cheng , MD, PHD 2 , Catherine C. Cowie , PHD 3 , Desmond E. Williams , MD, PHD 1 , Linda Geiss , MA 1 , Michael M. Engelgau , MD 1 and Frank Vinicor , MD, MPH 1 1 Division of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 2 Division of Information Technology, Northrop Grumman, Atlanta, Georgia 3 National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland Address correspondence and reprint requests to Edward W. Gregg, PhD, Division of Diabetes Translation, Centers for Disease Control and Prevention, 4770 Buford Hwy., N.E., Mailstop K-10, Atlanta, GA 30341. E-mail: edg7{at}cdc.gov Abstract OBJECTIVE —To examine trends in the prevalence of diagnosed and undiagnosed diabetes and the proportion of total cases previously diagnosed, according to obesity status in the U.S. over the past 40 years. RESEARCH DESIGN AND METHODS —We assembled data from five consecutive cross-sectional national surveys: National Health Examination Survey I (1960–1962), National Health and Nutrition Examination Survey (NHANES) I (1971–1974), NHANES II (1976–1980), NHANES III (1988–1994), and NHANES 1999–2000. Diagnosed diabetes was ascertained, and height and weight were measured in adults aged 20–74 years in all surveys. In NHANES II, NHANES III, and NHANES 1999–2000, a fasting glucose level ≥126 mg/dl was used to identify cases among individuals not reporting diabetes. Design-based analyses and Bayesian models estimate the probability that prevalence of diabetes increased within four BMI groups (99.9%) were accompanied by nonsignificant increases in undiagnosed diabetes (2.0–2.4%, 66.6%). This resulted in an increase in total diabetes (5.3–8.2%, >99.9%) and a modest nonsignificant increase in the proportion of cases that were diagnosed (62–70%, 62.4%). However, these trends varied considerably by BMI level. In individuals with BMI ≥35 kg/m 2 , diagnosed diabetes increased markedly (from 4.9% in 1960, to 8.6% during 1976–1980, to 15.1% in 1999–2000; probabi