Type 2 Diabetes and Obesity in Mexican Pimas: Gene-Environment Interaction
Condition: Type 2 Diabetes Mellitus; Obesity
MeSH terms: Diabetes Mellitus; Obesity; Diabetes Mellitus, Type 2
Study type: Observational

Summary: 
      In 1995 we conducted a cross-sectional study to identify the effects of traditional and
      western environments on prevalence of type 2 diabetes mellitus (T2DM) and obesity in Pima
      Indians in Mexico and the United States. The Mexican Pimas live in a remote mountainous
      region and at that time had experienced little change from their traditional lifestyle.
      Nothing was known about their T2DM prevalence. A similar number of non-Pima Mexicans live in
      the same village. In contrast to the Mexican Pimas, the U.S. Pimas live in more westernized
      society and have a high prevalence of diabetes. We found that although T2DM and obesity were
      more prevalent in Mexican Pimas than non-Pimas, both Mexican groups had a significantly lower
      prevalence of these disorders than U.S. Pimas. The lifestyle of the Mexican population
      studied included a dramatically higher level of physical activity and a diet higher in fiber
      and lower in calories derived from fat compared with the U.S. Pimas. Since the U.S. and
      Mexican Pimas share a similar gene pool we concluded that even in populations genetically
      prone to T2DM and obesity, their development is determined largely by environmental
      circumstances.

      Since 1995 the environmental circumstances of the Mexican Pimas and non-Pimas have changed.
      The electrical supply to the region has increased, cars have become more prevalent and
      grocery stores have appeared. The impact of these changes on T2DM and obesity has not been
      examined. In light of these events, we propose to: 1) compare the current prevalence of T2DM
      and obesity in Mexican Pimas and non-Pima Mexicans to that present in 1995 with the same
      measures used previously, including height, weight, waist circumference, body composition by
      bioelectrical impedance, oral glucose tolerance and HbA1c; 2) compare current diet, physical
      activity and total energy expenditure in both Mexican Pimas and. non-Pima Mexicans using the
      same methods as the 1995 study to the previous results and 3) document the frequencies of
      T2DM and obesity-associated genetic variants in Mexican Pimas compared with U.S. Pimas and
      non-Pima Mexicans.
    

Detailed description: 
      In 1995 we conducted a cross-sectional study to identify the effects of traditional and
      western environments on prevalence of type 2 diabetes mellitus (T2DM) and obesity in Pima
      Indians in Mexico and the United States. The Mexican Pimas live in a remote mountainous
      region and at that time had experienced little change from their traditional lifestyle.
      Nothing was known about their T2DM prevalence. A similar number of non-Pima Mexicans live in
      the same village. In contrast to the Mexican Pimas, the U.S. Pimas live in more westernized
      society and have a high prevalence of diabetes. We found that although T2DM and obesity were
      more prevalent in Mexican Pimas than non-Pimas, both Mexican groups had a significantly lower
      prevalence of these disorders than U.S. Pimas. The lifestyle of the Mexican population
      studied included a dramatically higher level of physical activity and a diet higher in fiber
      and lower in calories derived from fat compared with the U.S. Pimas. Since the U.S. and
      Mexican Pimas share a similar gene pool we concluded that even in populations genetically
      prone to T2DM and obesity, their development is determined largely by environmental
      circumstances.

      Since 1995 the environmental circumstances of the Mexican Pimas and non-Pimas have changed.
      The electrical supply to the region has increased, cars have become more prevalent and
      grocery stores have appeared. The impact of these changes on T2DM and obesity has not been
      examined. In light of these events, we propose to: 1) compare the current prevalence of T2DM
      and obesity in Mexican Pimas and non-Pima Mexicans to that present in 1995 with the same
      measures used previously, including height, weight, waist circumference, body composition by
      bioelectrical impedance, oral glucose tolerance and HbA1c; 2) compare current diet, physical
      activity and total energy expenditure in both Mexican Pimas and. non-Pima Mexicans using the
      same methods as the 1995 study to the previous results and 3) document the frequencies of
      T2DM and obesity-associated genetic variants in Mexican Pimas compared with U.S. Pimas and
      non-Pima Mexicans.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Residents of Maycoba, Sonora, Mexico@@@@@@
      
Keywords: Obesity; Type 2 Diabetes Mellitus; Genetics; Energy Expenditure; Physical Activity