Glucose Level, Acculturation, and Glycosylated Hemoglobin: An Example of Biocultural Interaction

Abstract

Abnormal elevation of the 1c variety of normal hemoglobin A (%HbA1c) is used by clinicians to diagnose diabetes. As a measure of long‐term glucose status, %HbA1c may also be employed to indicate differences in mean glucose levels between populations. In a longitudinal study of the etiology of noninsulin dependent diabetes mellitus (NIDDM) in Amerindians, Dogrib adults living in several settlements in the Canadian Northwest Territories underwent oral glucose challenge. From the fasting blood samples, %HbA1c was determined to assess its utility in identifying diabetics and to determine the factors that influence its variation, as these may also be involved in the onset of NIDDM.The mean %HbA1c in the Dogrib sample is 4.73 ± .49. The upper 95% confidence limit is 5.68%, and values exceeding this level are abnormal. The disease sensitivity of this criterion is only 16%. Nevertheless, %HbA1c is correlated with fasting and hour‐2 glucose levels and is higher both in individuals with impaired glucose tolerance and in probable diabetics. The low level of % HbA1c in the Dogrib is the likely result of low carbohydrate intakes, given their continuing dependence on caribou hunting and fishing.%HbA1c level is influenced by log fasting triglyceride (LFT), age, and village of residence. %HbA1c is higher in the main Dogrib village than in the semi‐isolated settlements, even after %HbA1c is adjusted for LFT and age, and any one of caloric or carbohydrate intake, physical activity, and diabetic status. The difference in %HbA1c level parallels known differences between communities in acculturation‐influenced phenomena, including the direction of dietary shifts.