Natural selection and type 2 diabetes‐associated mortality in an isolated indigenous community in the valley of Oaxaca, southern Mexico

Environment driven changes in type 2 diabetes, overweight and obesity in an isolated Mixe community in the Valley of Oaxaca, southern Mexico

BACKGROUND

This study focused on type 2 diabetes mellitus (T2DM) in a group of adult Mixe, an Indigenous population from Oaxaca, Mexico. Mixe comprised an estimated 9.4% (n ≅ 90 000) of the Indigenous population in Oaxaca. Mexico.

OBJECTIVE

This study focused on a group of adult Mixe, an Indigenous population from Oaxaca, Mexico. To compare the prevalence of T2DM, overweight (OW), obesity (OB), and hypertension (HTN) between 2007 and 2017 for a small, isolated Mixe community in the Valley of Oaxaca, Mexico. We test whether or not environmental changes have affected T2DM prevalence.

METHODS AND MATERIALS

Demographic and medical record data were collected in the community in 2007 and 2017 from the medical clinic and the mayor's office. T2DM was medically diagnosed among adults (>34 years old), in 2007 (n = 730) and in 2017 (n = 829).

RESULTS

T2DM crude prevalence increased from 6.7% to 12.1% (p < .001) from 2007 to 2017. The mean age of the sample analyzed was 60.6 (SD = 9.7). Age-adjusted T2DM prevalence increased from 6.7% to 10.8% (p < .002). T2DM was 5.7%-5.5% among males (p < .53) and 7.1%-13.6% among females (p < .001). Sex-specific OW and OB simulation studies indicate females had 7% less OW in 2007, and males were unchanged compared with 2017. OB among males and females was significantly higher in 2017 compared with 2007 (increased by 15.2% and 8.3%, males and females, respectively). Sexes combined OW + OB increased 12.7% among males but was unchanged in females (-0.5%). In the sexes combined analysis, OW prevalence increased 12.7% to 27.1% (p < .001) and OB prevalence increased 10.7%-27.9% (p < .001) from 2007 to 2017. HTN did not change significantly from 2007 to 2017 (15.4% and 14.6%, respectively) (p = .63) in adults. Among T2DM individuals, the frequency of HTN was not significantly different in 2007 and 2017 (57.1% and 37%, respectively) (p = .65). Transition to a Western diet consisting of high-carbohydrate foods occurred at the same time as increased T2DM from 2007 to 2017, with a higher prevalence of T2DM noted among females in 2017.

CONCLUSIONS

An increased prevalence of T2DM, OW, and OB but not HTN was observed in the Mixe community from 2007 to 2017 and was associated with the adoption of a high-carbohydrate Western diet.

Divergent evolution and purifying selection of the Type 2 diabetes gene sequences in Drosophila: a phylogenomic study

The recently developed phylogenomic approach provides a unique way to identify disease risk or protective allele in any organism. While risk alleles evolve mostly under purifying selection, protective alleles are evolving either under balancing or positive selection. Owing to insufficient information, authors employed the phylogenomic approach to detect the nature of selection acting on type 2 diabetes (T2D) genes in Drosophila genus using various models of CODEML utility of PAML. The obtained result revealed that T2D gene sequences are evolving under purifying selection. However, only a few sites in membrane proteins encoded via CG8051, ZnT35C, and kar, are significantly evolving under positive selection under specific scenarios, which might be because of positive or adaptive evolution in response to changing niche, diet or other factors. In the near future, this information will be highly useful in the field of evolutionary medicine and the drug discovery process.

Secular trends are associated with the demographic and epidemiologic transitions in an indigenous community in Oaxaca, Southern Mexico

OBJECTIVE

To test the hypothesis that secular changes in body size and age at menarche are related to the demographic and epidemiologic transitions in an indigenous community in Oaxaca, southern Mexico.

METHODS

Data were derived from surveys of a Zapotec-speaking community conducted between 1968 and 2000. Segmented linear regressions of height, weight, BMI and recalled age at menarche on year of birth in cohorts of adults born before and after the demographic transition were used to evaluate secular changes. Corresponding comparisons of body size (MANCOVA controlling for age) and age at menarche (status quo, probit analysis) were done for samples of children and adolescents born before and after the epidemiological transition.

RESULTS

Height and weight increased in adults born after the demographic transition (mid-1950s), and especially in children and adolescents born after the epidemiological transition (mid-1980s). Age at menarche also decreased significantly in women born after the demographic transition, but at a more rapid estimated rate in adolescents born after the epidemiological transition. Secular gains in body weight were proportional to those for height among children and adolescents, but adults, males more so than females, gained proportionally more weight.

CONCLUSIONS

The secular trend in height in adults of both sexes was associated with the decade of the demographic transition in the mid-1950s. Significant secular gains in size attained and age at menarche occurred in children and youth born after the epidemiologic transition which likely reflected improved health and nutritional conditions since the mid-1980s.