Effects of Traditional and Western Environments on Prevalence of Type 2 Diabetes in Pima Indians in Mexico and the U.S.

  1. Leslie O. Schulz, PHD1,
  2. Peter H. Bennett, MB, FRCP2,
  3. Eric Ravussin, PHD3,
  4. Judith R. Kidd, PHD4,
  5. Kenneth K. Kidd, PHD4,
  6. Julian Esparza, MS5 and
  7. Mauro E. Valencia, PHD5
  1. 1Department of Health Sciences, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin
  2. 2Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
  3. 3Pennington Biomedical Research Center, Baton Rouge, Louisiana
  4. 4Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
  5. 5Centro de Investigacion en Alimentación y Desarrollo A.C., Hermosillo, Mexico
  1. Address correspondence and reprint requests to Dr. Eric Ravussin, Pennington Biomedical Research Center, 6400 Perkins Rd., Baton Rouge, LA 70808. E-mail: ravusse{at}pbrc.edu

Abstract

OBJECTIVE—Type 2 diabetes and obesity have genetic and environmental determinants. We studied the effects of different environments on these diseases in Pima Indians in Mexico and the U.S.

RESEARCH DESIGN AND METHODS—Adult Pima-Indian and non-Pima populations in the Sierra Madre mountains of Mexico were examined using oral glucose tolerance tests and assessments for obesity, physical activity, and other risk factors. Results were compared with those from Pima Indians in Arizona. Both Pima populations were typed for DNA polymorphisms to establish their genetic similarity.

RESULTS—The age- and sex-adjusted prevalence of type 2 diabetes in the Mexican Pima Indians (6.9%) was less than one-fifth that in the U.S. Pima Indians (38%) and similar to that of non-Pima Mexicans (2.6%). The prevalence of obesity was similar in the Mexican Pima Indians (7% in men and 20% in women) and non-Pima Mexicans (9% in men and 27% in women) but was much lower than in the U.S. Pima Indians. Levels of physical activity were much higher in both Mexican groups than in the U.S. Pima Indians. The two Pima groups share considerable genetic similarity relative to other Native Americans.

CONCLUSIONS—The much lower prevalence of type 2 diabetes and obesity in the Pima Indians in Mexico than in the U.S. indicates that even in populations genetically prone to these conditions, their development is determined mostly by environmental circumstances, thereby suggesting that type 2 diabetes is largely preventable. This study provides compelling evidence that changes in lifestyle associated with Westernization play a major role in the global epidemic of type 2 diabetes.

Footnotes

  • A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

    • Accepted April 24, 2006.
    • Received January 19, 2006.
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