CoChat
Sign Up
Cited by 423Indigenous Health and EducationDiabetes, Cardiovascular Risks, and LipoproteinsObesity, Physical Activity, Diet

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

Open access
Schulz, Leslie O., Bennett, Peter H., Ravussin, Eric, Kidd, Judith R., Kidd, Kenneth K., Esparza, Julian, Valencia, Mauro E.·2006·Diabetes Care
DOI 10.2337/dc06-0138
Open this paper in CoChat — free accountOpen PDF

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.

AI snapshot

Written from the paper’s full text.

TL;DR

Pima Indians in a traditional Mexican environment had much lower type 2 diabetes and obesity prevalence than genetically similar Pima Indians in the U.S., despite sharing a similar gene pool. The findings suggest that environmental/lifestyle factors associated with Westernization largely determine whether genetically susceptible populations develop type 2 diabetes.

Key findings

  • Age- and sex-adjusted type 2 diabetes prevalence was 6.9% in Mexican Pima Indians, 38% in U.S. Pima Indians, and 2.6% in non-Pima Mexicans; the U.S. Pima prevalence was 5.5 times higher than Mexican Pima and 16 times higher than non-Pima Mexicans (P < 0.01).
  • Obesity was similar in Mexican Pima Indians (7% men, 20% women) and non-Pima Mexicans (9% men, 27% women) but much higher in U.S. Pima Indians (63.8% men, 74.8% women).
  • Physical activity was much higher in both Mexican groups than in U.S. Pima Indians: moderate-to-heavy activity was ~2.5-fold higher in Mexican men and 7-fold higher in Mexican women than in their U.S. Pima counterparts.
  • The two Pima groups clustered together genetically relative to other Native Americans, with a bootstrap support value of 95% (947 of 1,000), indicating a very similar gene pool.

Methods

  • Cross-sectional study of adult Pima and non-Pima Mexicans in the Sierra Madre mountains of Mexico, examined with oral glucose tolerance tests, anthropometry, physical activity questionnaires, and 24-h dietary recalls; results were compared with U.S. Pima Indians from the Gila River Indian Community in Arizona examined during June 1995–June 1996.
  • Diabetes and impaired glucose tolerance were defined by 1999 WHO criteria; obesity was defined as BMI ≥30 kg/m², with body fat estimated by bioelectrical impedance.
  • Genetic similarity was assessed by typing 309 independent DNA markers in 52 unrelated full Pima Indians from Mexico and 52 full Pima Indians from the U.S.; prevalence rates were directly standardized for age and sex.

Limitations

  • The paper states that cause and effect cannot be proven from this cross-sectional study, although it proposes that low diabetes prevalence in the Mexican populations is largely due to lesser obesity.
  • The paper states that a difference between the Pima populations in frequencies of unidentified diabetes susceptibility genes due to genetic drift or founder effects cannot be excluded.
  • The paper notes that dietary intake was not evaluated in the U.S. Pima sample used for comparison; an earlier U.S. Pima dietary study was cited instead. Evident from the text: participation was 77% of eligible Mexican Pima Indians and 71% of non-Pima Mexicans, and the diabetes difference between Mexican Pima and non-Pima Mexicans was not statistically significant.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.2337/dc06-0138

Cites

28 of 28 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 13 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The age-and sex-adjusted prevalence of type 2 diabetes in Mexican Pima Indians was 6.9%.

    “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%).”
    Quote in the paperSubstantial claim
  • Findingown data

    The age-and sex-adjusted prevalence of type 2 diabetes in non-Pima Mexicans was 2.6%.

    “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%).”
    Quote in the paperSubstantial claim
  • Findingown data

    The age-and sex-adjusted prevalence of type 2 diabetes in U.S. Pima Indians was 38%.

    “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%).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.
  • Findingown data

    The two Pima groups share considerable genetic similarity relative to other Native Americans.

    “The two Pima groups share considerable genetic similarity relative to other Native Americans.”
    Quote in the paperSubstantial claim
  • Findingown data

    Levels of physical activity were much higher in both Mexican groups than in U.S. Pima Indians.

    “Levels of physical activity were much higher in both Mexican groups than in the U.S. Pima Indians.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.
  • May combine two claims. 9
  • Classified as probably not a substantial claim. 6

  • May combine two claims.

    Findingown data

    The two Pima groups are not identical but cluster together and share common ancestry distinct from other Native Americans with a supporting bootstrap value of 95% (947 of 1,000).

    “The two Pima groups are not identical but cluster together and share common ancestry distinct from other Native Americans with a supporting bootstrap value of 95% (947 of 1,000).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    BMI, waist and hip circumference, and percent body fat were similar in Pima and non-Pima Mexican men and women, but markedly greater in the U.S. Pima group.

    “BMI, waist and hip circumference, and percent body fat were similar in the Pima and non-Pima Mexican men and women, respectively, but markedly greater in the U.S. Pima group.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.

  • May combine two claims.

    Findingown data

    The prevalence of obesity was similar in Mexican Pima Indians and non-Pima Mexicans but much lower than in U.S. Pima Indians.

    “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.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.

  • May combine two claims.

    Findingown data

    Levels of moderate to heavy physical activity were ~2.5-fold higher in Mexican men and 7-fold higher in Mexican women than in their U.S. Pima-Indian counterparts.

    “The levels of moderate to heavy physical activity were ϳ2.5-fold higher in the Mexican men and 7-fold higher in the Mexican women than in their U.S. Pima-Indian counterparts.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.

  • May combine two claims.

    Premisecitation

    Obesity and physical inactivity are major behavioral risk factors for type 2 diabetes.

    “Obesity and physical inactivity are major behavioral risk factors for the disease (22,23), although other factors such as low birth weight, breast-feeding, and the intrauterine environment also play a role (24 -26).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [22] Knowler WC, Pettitt DJ, Savage PJ, Bennett PH: Diabetes incidence in Pima Indians: contributions of obesity and parental diabetes. Am J Epidemiol 113:144–156, 1981 source

      Not checked in the free run.

    • cites [23] Kriska AM, Saremi A, Hanson RL, Bennett PH, Kobes S, Williams DE, Knowler WC: Physical activity, obesity, and the incidence of type 2 diabetes in a high-risk population. Am J Epidemiol 158:669–675, 2003 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    All subjects were administered an activity questionnaire.

    “All subjects were administered an activity questionnaire (13).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] Kriska AM, Knowler WC, LaPorte RE, Drash AL, Wing RR, Blair SN, Bennett PH, Kuller LH: Development of questionnaire to examine relationship of physical activity and diabetes in Pima Indians. Diabetes Care 13:401–411, 1990 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given

    A difference between these Pima populations in frequencies of as yet unidentified diabetes susceptibility genes resulting from genetic drift or founder effects cannot be excluded.

    “Nonetheless, a difference between these Pima populations in frequencies of as yet unidentified diabetes susceptibility genes resulting from genetic drift or founder effects cannot be excluded.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    Percent body fat was estimated from bioelectrical impedance using an equation developed for the U.S. Pima Indians.

    “Percent body fat was estimated from bioelectrical impedance (BIA-103; RJL Systems) using an equation developed for the U.S. Pima Indians (12).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] Rising R, Swinburn B, Larson K, Ravussin E: Body composition in Pima Indians: validation of bioelectrical resistance. Am J Clin Nutr 53:594–598, 1991 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Complete glucose tolerance data were obtained for 77.2% of the eligible Mexican Pima Indians and for 71.5% of the non-Pima Mexicans.

    “Complete glucose tolerance data were obtained for 77.2% of the eligible Mexican Pima Indians and for 71.5% of the non-Pima Mexicans.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    U.S. Pima Indians have the world's highest recorded prevalence and incidence of type 2 diabetes.

    “The Pima Indians in the U.S. reside mainly in the desert regions of Arizona and have the world's highest recorded prevalence and incidence of type 2 diabetes (5,6).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [5] Bennett PH, Burch TA, Miller M: Diabetes mellitus in American (Pima) Indians. Lancet 2:125–128, 1971 source

      Not checked in the free run.

    • cites [6] Knowler WC, Pettitt DJ, Saad MF, Bennett PH: Diabetes mellitus in the Pima Indians: incidence, risk factors and pathogenesis. Diabetes Metab Rev 6:1–27, 1990 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Even in a genetically highly susceptible population, type 2 diabetes is not inevitable and is preventable in environments that promote low levels of obesity and high levels of physical activity.

    “The findings indicate that, even in a genetically highly susceptible population, type 2 diabetes is not inevitable and is preventable in environments that promote low levels of obesity and high levels of physical activity.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.
    • Rests on an assumption: The cross-sectional prevalence differences reflect lifetime risk of diabetes.

  • May combine two claims.

    Interpretationown data

    Based on genetic data, U.S. Pima and Mexican Pima Indians are closely related to each other and share a very similar gene pool.

    “Based on these data, the U.S. Pima and the Mexican Pima Indians are closely related to each other and share a very similar gene pool.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Directly standardized age- and sex-adjusted prevalence rates of diabetes were compared among the populations, using the combined Mexican Pima and non-Pima samples as the reference population.

    “Directly standardized age-and age-and sex-adjusted prevalence rates of diabetes were compared among the populations, using the combined Mexican Pima and non-Pima samples (within the age and sex groups shown in Table 1) as the reference population.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    Diabetes and impaired glucose tolerance were defined using 1999 World Health Organization criteria.

    “Diabetes and impaired glucose tolerance were defined using 1999 World Health Organization criteria (11).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [11] World Health Organization Consultation-Group: Definition, Diagnosis and Classification of Diabetes Mellitus and Its Complications. Part 1. Diagnosis and Classification of Diabetes Mellitus. Geneva, World Health Org., 1999, p. 59

      Not checked in the free run.

14 of 14

  • The paper relies on this without support.

    The U.S. Pima-Indian sample used for comparison is typical of the larger Pima population examined in the ongoing longitudinal study.

    “The data in the U.S. Pima-Indian sample used for comparison are typical of those seen in the larger Pima population examined in the ongoing longitudinal study.”

  • The paper relies on this without support.

    The 24-h dietary recall accurately represents the usual diet of the Mexican populations.

    “A 24-h dietary recall was conducted in the Mexican populations.”

  • The paper relies on this without support.

    The non-Pima Mexicans have no parental Amerindian heritage.

    “The non-Pima Mexicans reported no parental Amerindian heritage.”

  • The paper relies on this without support.

    The Pima heritage classification accurately identifies full and part Pima individuals.

    “Subjects were considered full Pima if they reported that both their parents were full Pima and part Pima if one parent was Pima.”

  • The paper relies on this without support.

    The cross-sectional prevalence differences reflect lifetime risk of diabetes.

    “The much lower prevalence of diabetes in the Mexican Pima Indians aged Ն55 years (9%) compared with that in the U.S. Pima Indians (77%) suggests that the lifestyle of the Mexican Pima Indians may result in life-long protection from type 2 diabetes, even among the majority of those who are genetically susceptible.”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Large disparities in both the prevalence of established risk factors and the rates of cardiovascular events in genetically similar populations both over time and across regions confirm that genetic effects are subordinate to lifestyle and environmental influences.

    “large disparities in both the prevalence of established risk factors and the rates of cardiovascular events in genetically similar populations both over time and across regions confirm that genetic effects are subordinate to lifestyle and environmental influences.50 -52,57-59”

    From Beyond Established and Novel Risk Factors: Lifestyle Risk Factors for Cardiovascular Disease (2008) · cites this paper as [52]

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Related

Authors
Schulz, L. O., Bennett, P. H., Ravussin, E., Kidd, J. R., Kidd, K. K., Esparza, J., & Valencia, M. E.
Affiliations
  • University of Wisconsin–Milwaukee (US)
  • National Institutes of Health (US)
  • Pennington Biomedical Research Center, Baton Rouge, Louisiana
  • Yale University (US)
  • Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
  • Centro de Investigacion en Alimentación y Desarrollo A.C., Hermosillo, Mexico
  • Centro de Investigación en Alimentación y Desarrollo (MX)
ORCID
Venue
Diabetes Care
Publisher
American Diabetes Association
Published
2006-08-01
Volume
29
Issue
8
Pages
1866-1871
ISSN
  • 0149-5992 (ISSN-L)
  • 1935-5548
DOI
10.2337/dc06-0138
OpenAlex
W2098164111
Semantic Scholar
f27562df093bb1339566f61b0f3a457411b4880f
Cited by
420
References
28
Citations by year
2026: 9 · 2025: 16 · 2024: 22 · 2023: 21 · 2022: 20 · 2021: 15 · 2020: 29 · 2019: 17 · 2018: 11 · 2017: 19 · 2016: 16 · 2015: 16 · 2014: 24 · 2013: 31 · 2012: 21
FWCI
41.63
Type
journal article
Language
en
Open access
Locations
  • Diabetes Care (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health
  • National Institute of General Medical Sciences (GM 57672, P01GM057672)
  • National Institute of Diabetes and Digestive and Kidney Diseases (76-DK-0256, DK-49957)
Topics
  • Health Sciences › Health Professions › General Health Professions › Indigenous Health and Education
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes, Cardiovascular Risks, and Lipoproteins
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Obesity, Physical Activity, Diet
Keywords
type 2 diabetes, Pima Indians, diabetes prevalence, obesity, physical activity, Westernization, lifestyle modification, genetic susceptibility, Sierra Madre, diabetes prevention, Native Americans, DNA polymorphism
MeSH terms
Adult, Culture, Diabetes Mellitus, Type 2, Diet, Female, Humans, Indians, North American, Male, Mexico, Middle Aged, Motor Activity, Obesity, Sex Characteristics, United States, Age Distribution

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review