Obesity and Undiagnosed Diabetes in the U.S.

  1. Christina C. Wee, MD, MPH1,
  2. Mary Beth Hamel, MD, MPH1,
  3. Annong Huang, MD, MPH, PHD1,
  4. Roger B. Davis, SCD1,
  5. Murray A. Mittleman, MD, DRPH2 and
  6. Ellen P. McCarthy, PHD, MPH1
  1. 1Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
  2. 2Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
  1. Corresponding author: Christina C. Wee, cwee{at}


OBJECTIVE—To study whether obese individuals, who are at higher risk for diabetes and disparities in care than nonobese individuals, are more likely to have undiagnosed diabetes.

RESEARCH DESIGN AND METHODS—We performed an analysis of 5,514 adult participants in the 1999–2004 National Health and Nutrition Examination Survey. Particpants were interviewed about sociodemographic and medical data, including whether they had been diagnosed with diabetes, and were examined for height, weight, and fasting plasma glucose level ≥126 mg/dl or by previous physician diagnosis. After categorizing participants into normal weight, overweight, and obese according to BMI, the prevalance and diagnosis of diabetes across BMI categories was compared using χ2.

RESULTS—Of the 9.8% (weighted sample) of participants who had diabetes, based on fasting glucose levels and self-reported diagnosis, 28.1% were undiagnosed, translating to an estimated 5.2 million people in the U.S. population. The proportion undiagnosed was not significantly different among normal-weight (22.2%), overweight (32.5%), or obese adults (27.4%). Nevertheless, obese adults comprise more than half of the undiagnosed diabetes cases (2.7 million). Relative to normal-weight adults, the adjusted odds ratio (OR) for having undiagnosed diabetes was 1.50 (0.73–3.08) in overweight and 1.37 (0.72–2.63) in obese adults.

CONCLUSIONS—Despite a higher underlying risk of diabetes and widespread clinical recognition of this higher risk, obesity does not increase the likelihood that an individual's diabetes will be diagnosed.


  • Published ahead of print at on 28 May 2008.

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    • Accepted May 18, 2008.
    • Received September 24, 2007.
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  1. Diabetes Care vol. 31 no. 9 1813-1815
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