Emöke J. E. Szathmary

Dietary change and plasma glucose levels in an Amerindian population undergoing cultural transition

Dietary change among adult Dogrib Indians of the Northwest Territories, Canada, is examined in conjunction with differences in mean glucose levels among more acculturated-less acculturated settlements. There are significant differences in the intake components derived from non-traditional foods by community and by age. However, the traditional food base is stable. This pattern suggests that dietary acculturation may initially consist of the addition of new foods to a stable traditional dietary, rather than replacement of traditional foods. The net effect is an increase in caloric intake. Age-sex-adjusted plasma glucose levels among four Dogrib settlements did not differ significantly. Comparison of participants who had been tested in a 1979 investigation of glucose tolerance showed that the current lack of intervillage differences can be attributed to an unexplained decrease of mean plasma glucose in the most acculturated village. Either dietary shift does not influence glucose levels, or, its effect can be detected only in conjunction with some other environmental factor. Among the Dogrib, acculturation-associated dietary changes are clearly present. However, their role in influencing plasma glucose levels still needs to be demonstrated.

The effect of Gc genotype on fasting insulin level in Dogrib Indians

SummaryThe metabolically active form of vitamin D, 1,25-(OH)2D3, is involved in the regulation of insulin level. Because the serum group-specific component (Gc) binds vitamin D, it is worth knowing whether differences in basal insulin levels are associated with Gc genotype. Such differences would warrant further investigation to clarify whether selection maintains Gc polymorphism through differential risk of Gc genotypes to diseases that involve insulin. Blood samples were collected in a study designed to address issues in the etiology of non-insulin-dependent diabetes mellitus in Amerindians. Fasting insulin levels and Gc genotype (including subtypes of Gc1) were determined for 144 adult Dogrib Indians of the Northwest Territories, Canada. Hierarchical regression of log10 transformed fasting insulin on age and adiposity within each sex showed that age had no effect on insulin level, but adiposity as measured by the body mass index (BMI) had a very highly significant effect. Analysis of covariance of log10 fasting insulin by sex, by Gc genotype and with adjustment for the effects of the covariate, BMI, was very highly significant. All interaction terms in the model were nonsignificant. The only variable that had a significant effect after adjustment for the BMI was Gc genotype (F4,133=3.71; P=0.007). Covariance analysis was repeated on a subset of the sample (124 people). The reduced data set excluded all individuals who had, on at least one occasion, abnormal response to oral glucose challenge [impaired glucose tolerance (IGT) or noninsulin-dependent diabetes mellitus (NIDDM)]. Again, after correction for the effects of the BMI, only Gc genotype had a significant effect on fasting insulin level (F4,113=2.61; P=0.040). Homozygotes for Gc 1F-1F had the lowest measures of fasting insulin.

Dietary acculturation among the Dogrib Indians of the Canadian northwest territories

The Dogrib Indians of the Canadian Northwest Territories are undergoing change from a “traditional” to a “modem” life‐style. Such transitions are often associated with the appearance of previously unknown chronic diseases. This study was undertaken to identify patterns of dietary acculturation that may be associated with the appearance of hyperglycemia and diabetes in a population that currently has low prevalence of these conditions. Dietary data were collected from adults (> 27 yr old) using three instruments: a 24‐hr recall, a report of intake on a usual winter day, and a food‐frequency questionnaire. Dietary change apparently involves additions to the diet of non‐traditional foods rather than replacement of traditional foods by non‐traditional foods. This pattern is especially evident among younger Dogrib and those residing in the main village. With acculturation, the macronutrient composition changes from that of a hunting‐based diet (high protein, moderate fat, low carbohydrate) to one with relative...