Recent epidemiologic trends of diabetes mellitus among status Aboriginal adults

Background:

Little is known about longitudinal trends in diabetes mellitus among Aboriginal people in Canada. We compared the incidence and prevalence of diabetes, and its impact on mortality, among status Aboriginal adults and adults in the general population between 1995 and 2007.

Methods:

We examined de-identified data from Alberta Health and Wellness administrative databases for status Aboriginal people (First Nations and Inuit people with treaty status) and members of the general public aged 20 years and older who received a diagnosis of diabetes mellitus from Apr. 1, 1995, to Mar. 31, 2007. We calculated the incidence and prevalence of diabetes and mortality rate ratios by sex and ethnicity in 2007. We examined the average relative changes per year for longitudinal trends.

Results:

The average relative change per year in the prevalence of diabetes showed a smaller increase over time in the Aboriginal population than in the general population (2.39 v. 4.09, p < 0.001). A similar finding was observed for the incidence of diabetes. In the Aboriginal population, we found that the increase in the average relative change per year was greater among men than among women (3.13 v. 1.88 for prevalence, p < 0.001; 2.60 v. 0.02 for incidence, p = 0.001). Mortality among people with diabetes decreased over time to a similar extent in both populations. Among people without diabetes, mortality decreased in the general population but was unchanged in the Aboriginal population (−1.92 v. 0.11, p = 0.04). Overall, mortality was higher in the Aboriginal population than in the general population regardless of diabetes status.

Interpretation:

The increases in the incidence and prevalence of diabetes over the study period appeared to be slower in the status Aboriginal population than in the general population in Alberta, although the overall rates were higher in the Aboriginal population. Mortality decreased among people with diabetes in both populations but was higher overall in the Aboriginal population regardless of diabetes status.The health of Aboriginal people in Canada is generally poorer than their non-Aboriginal counterparts, and diabetes mellitus is a significant contributor.^1,2 Studies have shown that type 2 diabetes and its complications occur at rates two to five times higher in Canada’s Aboriginal population than in the general population.^3–7 In response, diverse diabetes programs have materialized, including various community-based prevention and screening projects.^8–10 The federally funded Aboriginal Diabetes Initiative was created to emphasize health promotion and diabetes prevention.¹¹ In addition, numerous Aboriginal communities have established their own diabetes and health programs.¹²Accurate diabetes surveillance data are essential for governments and health care organizations to plan health care delivery and translate knowledge into policy and funding decisions. However, research into the longitudinal trends of diabetes in Aboriginal populations is scarce. For the most part, data have come from small, community-based studies and self-reported surveys. Population-based studies of primary data are few and have been conducted only for limited periods. Even less is known about outcomes, mortality in particular, among Aboriginal individuals with diabetes.The use of administrative data is becoming more common for tracking diabetes in Canada.¹³ The National Diabetes Surveillance System uses administrative health data to document the burden of the disease, but it has little information on Aboriginal people. Dyck and colleagues recently used the methodology of the National Diabetes Surveillance System to examine the incidence and prevalence of diabetes among Aboriginal people in the province of Saskatchewan,¹⁴ and similar analyses were conducted in Manitoba and Ontario.^15,16As part of the Alberta Diabetes Surveillance System, we conducted this study to compare the incidence and prevalence of diabetes among people 20 years and older in the status Aboriginal population (First Nations and Inuit people with treaty status) and the general population in the province of Alberta between 1995 and 2007. We also compared trends in mortality in the two populations among people with and without diabetes.