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Cohort study
Racial Disparities in the Incidence of Diabetes in Canada
  1. Terri H Lipman
  1. School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA
  1. Correspondence to Terri H Lipman
    School of Nursing, University of Pennsylvania, 418 Curie Blvd, Philadelphia, PA 19104, USA; lipman{at}

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Implications for practice and research

  • Screening for type 2 diabetes may identify those at risk who are at need for intervention.

  • Body mass index (BMI) cutoff points, as a standard screening measure, may differ among racial/ethic grsoups.

  • Future studies should focus on those diabetes risk factors that are most predictive of diabetes across racial/ethnic groups.


Obesity is a major public health concern and affects approximately 30% of adults in the USA1 and as a result, type 2 diabetes in adults is occurring in epidemic proportions. The total number of people with diabetes worldwide is projected to rise from 171 million in 2000 to 366 million in 2030.2

Screening for type 2 diabetes and for diabetes risk factors has received considerable attention. Data have shown that with intensive blood glucose control and lifestyle intervention of those at risk, type 2 diabetes can be prevented.3 Many advocate screening with BMI, as BMI has been shown to be strongly associated with the development of type 2 diabetes. But are there racial differences in the BMI score that is predictive of type 2 iabetes?

The purpose of the study by Chiu et al was to compare diabetes risk among white, South Asian, Chinese and Black subjects in Canada and derive racially appropriate BMI cutoff values that predict diabetes risk.


This study was a compilation of two large Canadian Health Surveys. Subject participants lived in Ontario and were ≥30 years at the time of the survey. The study period was 12.8 years. Survey questions included sociodemographic characteristics and risk factors for the development of diabetes. When possible, reported data were linked to administrative records that included the hypertension and diabetes databases to validate reported information.


Data from approximately 60 000 individuals in the Canadian populations were analysed. A total of 4076 subjects were diagnosed with type 2 diabetes. The incidence of type 2 diabetes was significantly higher in South Asian, black and Chinese subjects than in whites subjects. South Asians were diagnosed with diabetes almost 10 years younger than whites. BMI was predictive of type 2 diabetes at a cutoff of 30 for white subjects, 24 for South Asians, 25 for Chinese and 26 for Blacks. The authors concluded that there is a need for ethnically tailored diabetes prevention strategies and ethnically specific BMI cutoff points for assessing diabetes risk.


This study was important in demonstrating ethnic differences in the incidence of type 2 diabetes. Nurses need to know which populations are at high risk for the development of diabetes and focus on diabetes prevention. In addition, the authors are correct that, with knowledge of racial disparities comes the responsibility to develop culturally relevant interventions targeted at changes in eating and activity. There are limitations of this study related to the incidence data. The data are self-reported. It is possible that those with diabetes are more or less likely to respond to surveys, thereby affecting incidence rates. There may also be racial differences in willingness to respond to surveys. Although subjects reported that they had been diagnosed with diabetes there was no way to validate the diagnosis, in the majority of cases.

The authors' data on racial differences in the BMI cutoff for diabetes risk were very interesting. A BMI cutoff of 30 kg/m2 is commonly regarded as the cutoff for assessing diabetes risk. According to the data in this study, a large numbers of South Asian, Black and Chinese subjects at risk for diabetes would not be targeted when using a BMI target of 30. These data must be interpreted with caution. Again, when using self-reported data there is the possibility of inaccurate reporting of height and weight. The major limitation of the study is that no data were collected on waist circumference or waist/hip ratio. It has been well documented that diabetes risk is highly associated with abdominal adiposity and that there are racial differences in fat distribution. It is possible that although some racial groups with diabetes had lower BMI, all races may have had comparable abdominal adiposity, and if so, nurses should focus on waist circumference when assessing for diabetes risk. Clearly, more studies are needed on racial differences in diabetes and so appropriate populations can be targeted and appropriate intervention can be developed.

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  • Competing interests None.

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