University of Toronto - Faculty of Medicine

 

Author
The initial draft of this chapter was prepared by Baiju Shah, MD, PhD, FRCPC

 

• The development of type 2 diabetes amongst Aboriginal people who have been exposed to a Westernized lifestyle has recently increased to epidemic proportions.
• Both IGT and type 2 diabetes are starting to occur in much younger individuals as compared to Caucasian populations.
• It is not uncommon to see children and adolescents presenting with type 2 diabetes.
• Aboriginal women are at increased risk for the development of gestational diabetes.
• Epidemiologists have long suspected that changes in diet and physical activity are the root causes for this dramatic increase in type 2 diabetes.
• In many communities, there has been a transition form a semi-nomadic hunter and gatherer existence characterized by periods of feasts and famine with high levels of physical activity to one of nutrient excess and inactivity. Studies have documented that obesity is a major problem amongst Aboriginal children and is associated with increased television watching and decreased physical activity.
• In addition to environmental changes, genetic susceptibility plays an important role. Survival in an environment characterized by feast and famine will naturally select for those individuals who can store energy efficiently. This ability has been referred to as the thrifty genotype. The ability to store energy efficiently in times of starvation would clearly provide a survival advantage. However, the same genotype would be a liability in a society if nutrient excess became the norm.

 

• According to the 2006 Census, visible minorities made up 13% of the Canadian population, and up to 20% in provinces like Ontario and British Columbia. In addition, the visible minority population is growing much more rapidly than the rest of the population.
• Ethnic disparities in diabetes prevalence have been documented in many multi-ethnic countries, including Canada, the United States and the United Kingdom. High risk populations include those of Hispanic, South Asian, Asian and African descent.
• These populations also have higher rates of metabolic syndrome, impaired glucose tolerance, insulin resistance, type 2 diabetes in childhood and gestational diabetes. This occurs at lower degrees of obesity than in European populations.
• These metabolic changes are thought to be due, in part, to Westernization of lifestyles and genetic susceptibility.

 

• The long-term chronic complications of diabetes are now occurring with high frequency in these populations.
• The First Nations population appears to be particularly susceptible to diabetic nephropathy and cardiovascular disease. There is limited information about Métis and Inuit populations.
• The risks for micro- and macrovascular complications among other ethnic groups compared to people with European origins are uncertain, depending on the populations studied. In general, people of African origin with diabetes are at particularly high risk for proteinuria and nephropathy, while people of South Asian origin with diabetes may be at independent risk for cardiovascular disease.

 

• Diabetes prevention strategies for Aboriginal people and for visible minority populations must be culturally and socially appropriate and conform to the health beliefs and lifestyle of the communities involved.
• This is feasible and effective as illustrated by Australian Aboriginal and American Zuni Indians studies, which document a significant decrease in type 2 diabetes associated with increased physical activity and appropriate nutritional intervention.
• Several of the landmark diabetes prevention trials (e.g., the Da Qing study and the Indian Diabetes Prevention Program) have occurred in countries that are sources for large numbers of Canadian immigrants, showing that diabetes prevention with lifestyle interventions and/or metformin is effective in these populations.

 

• Treatment of diabetes and its complications in these populations should follow current clinical practice guidelines.
• There is a growing body of evidence to support the use of culturally-specific community diabetes management programs delivered in partnership with the target communities.

References

1. Anand SS, Yusuf S, Vuksan V, et al. Differences in risk factors, atherosclerosis, and cardiovascular disease between ethnic groups in Canada: the Study of Health Assessments and Risk in Ethnic groups (SHARE). Lancet 2000;356:279-84.
2. Davis TM, Cull CA, Holman RR. Relationship between ethnicity and glycemic control, lipid profiles, and blood pressure during the first 9 years of type 2 diabetes: UK Prospective Diabetes Study (UKPDS 55). Diabetes Care 2001;24:1167-74.
3. Gahagan S, Silverstein J. Prevention and treatment of type 2 diabetes mellitus in children, with special emphasis on American Indian and Alaska Native children. Pediatrics 2003;112:328-47.
4. Green C, Blanchard J, Young TK, et al. The epidemiology of diabetes in the Manitoba-registered First Nation population: current patterns and comparative trends. Diabetes Care 2003;26:1993-8.
5. Hanley AJG, Harris SB, Gittelsohn J, Wolever TMS, Saksvig B, Zinman B. Overweight among children and adolescents in a Native Canadian community: prevalence and associated factors. Am J Clin Nutr 2000;71:693-700.
6. Hanley AJ, Harris SB, Mamakeesick M, et al. Complications of type 2 diabetes among Aboriginal Canadians: prevalence and associated risk factors. Diabetes Care 2005;28:2054-7.
7. Karter AJ, Ferrara A, Liu JY, et al. Ethnic disparities in diabetic complications in an insured population. JAMA 2002;287:2519-27.