Was the Historic Contribution of Spain to the Mexican Gene Pool Partially Responsible for the Higher Prevalence of Type 2 Diabetes in Mexican-Origin Populations?
The Spanish Insulin Resistance Study Group, the San Antonio Heart Study, and the Mexico City Diabetes Study
- Carlos Lorenzo, MD1,
- Manel Serrano-Rios, MD2,
- Maria T. Martinez-Larrad, MD2,
- Rafael Gabriel, MD3,
- Ken Williams, MS1,
- Clicerio Gonzalez-Villalpando, MD4,
- Michel P. Stern, MD1,
- Helen P. Hazuda, PHD1 and
- Steven M. Haffner, MD1
- 1Department of Medicine, Division of Clinical Epidemiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- 2Department of Internal Medicine, Hospital Universitario de San Carlos, Madrid, Spain
- 3Department of Internal Medicine, Hospital de La Princesa, Madrid, Spain
- 4Center of Studies in Diabetes, American British Cowdray Hospital, Mexico City, Mexico
Abstract
OBJECTIVE—Mexican-American populations in San Antonio, Texas (SA-MA) and Mexico have a higher prevalence of type 2 diabetes than non-Hispanic whites in San Antonio (SA-NHW). However, the higher prevalence of type 2 diabetes in Mexican-origin populations might be related, in part, not to Native American genetic admixture but to Spanish genetic admixture.
RESEARCH DESIGN AND METHODS—Four population-based epidemiological surveys conducted with Mexican-origin and European-origin samples provided data relevant to this question. In all four surveys, type 2 diabetes was defined as fasting plasma glucose ≥7.0 mmol/l or 2-h glucose ≥11.1 mmol/l or use of antidiabetic agents.
RESULTS—A comparison of the two Mexican-origin populations showed that the age- and sex-adjusted prevalence of type 2 diabetes was lower in Mexico than in SA-MA (15.1 vs. 17.9%, P = 0.032). Between the two European-origin populations, the prevalence of type 2 diabetes was lower in SA-NHW than in Spain (6.2 vs. 9.1%, P < 0.0001), but differences were attenuated by adjustment for BMI or after stratification by education. In logistic regression analyses, type 2 diabetes was associated with Mexican ethnic origin after adjusting for age, education, BMI, and waist-to-hip ratio.
CONCLUSIONS—The prevalence of type 2 diabetes in Spain was intermediate between that in Mexican-origin populations and SA-NHW. Although the higher degree of Native American admixture is a major contributor to the higher rates of type 2 diabetes, we cannot completely rule out a partial contribution of Spanish admixture to diabetes susceptibility among Mexican- origin populations.
- MCDS, Mexico City Diabetes Study
- OR, odds ratio
- SAHS, San Antonio Heart Study
- SA-NHW, non-Hispanic whites in San Antonio
- SA-MA, Mexican-Americans in San Antonio
- SIRS, Spanish Insulin Resistance Study
- WHR, waist-to-hip ratio
Footnotes
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Address correspondence and reprint requests to Carlos Lorenzo, MD, Department of Medicine, Division of Clinical Epidemiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78284-7873. E-mail: lorenzo{at}uthscsa.edu.
Received for publication 4 May 2001 and accepted in revised form 4 September 2001.
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