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.
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.


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 > or =7.0 mmol/l or 2-h glucose > or =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.
Lorenzo
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Department of Medicine, Division of Clinical Epidemiology, University of Texas Health Science Center at San Antonio, 78284-7873, USA. lorenzo@uthscsa.edu
Serrano-Rios
M
M
Martinez-Larrad
M T
MT
Gabriel
R
R
Williams
K
K
Gonzalez-Villalpando
C
C
Stern
M P
MP
Hazuda
H P
HP
Haffner
S M
SM
D000367:Age Factors; D001824:Body Constitution; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D004522:Educational Status; D006630:Hispanic or Latino; D007333:Insulin Resistance; D016015:Logistic Models; D008800:Mexico / Q000453:epidemiology / Q000208:ethnology; D016017:Odds Ratio; D013030:Spain / Q000453:epidemiology; D013781:Texas / Q000453:epidemiology