Clinical trial NCT01168297: Type 2 Diabetes and Obesity in Mexican Pimas: Gene-Environment Interaction
Official title: Type 2 Diabetes and Obesity in Mexican Pimas: Gene-Environment Interaction
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Type 2 Diabetes Mellitus
Obesity
Keywords: Obesity
Type 2 Diabetes Mellitus
Genetics
Energy Expenditure
Physical Activity
Lead sponsor: National Institutes of Health Clinical Center (CC)
Sponsor class: NIH
First posted: 2010-07-23
Enrollment: 657
Sex: ALL
Minimum age (years): 18
Maximum age (years): 100
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Residents of Maycoba, Sonora, Mexico@@@@@@

Brief 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.

Eligibility criteria: * INCLUSION AND EXCLUSION CRITERIA:

Selection of Subjects:

-The entire adult population of Maycoba, Sonora, Mexico, will be invited to participate in the main study. Individuals will be eligible to participate if they are at least 18 years old and residents of Maycoba and able to give informed consent. There will be no further exclusion or inclusion criteria. For the doubly-labeled water studies pregnant women will be excluded, since pregnancy has profound effects on energy expenditure.

Primary outcomes:
measure: Diabetes
timeFrame: Time of examination
Secondary outcomes:
Other outcomes:
Locations:
city: Hermosillo
country: Mexico
facility: Centro de Investigacion en Alimentacion y Desarollo (CIAD)
Study officials:
affiliation: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
name: Robert L Hanson, M.D.
role: PRINCIPAL_INVESTIGATOR
References: