Report from the National Diabetes Surveillance System: Diabetes in Canada, 2008

National Diabetes Surveillance System (NDSS)

• The National Diabetes Surveillance System (NDSS) is a network of provincial and territorial diabetes surveillance systems. It was created to improve the breadth of information about the burden of diabetes in Canada so that policymakers, researchers, health practitioners, and the general public could make better public and personal health decisions. The NDSS includes federal and all provincial and territorial governments, non-governmental organizations, national Aboriginal groups, and researchers.
• In each province and territory, the health insurance registry database is linked to the physician billing and hospitalization databases, in which health data are primarily stored and reported by fiscal year. This report includes the most recent data available from the provinces and territories³, fiscal year, 2005-2006.
• The linked database is used to designate individuals who have diabetes⁴, based on the NDSS validated case criteria, which use the International Classification of Disease (ICD) standard diabetes codes.
• Currently, the NDSS case criteria do not include women with gestational diabetes. In addition, the criteria do not distinguish between diabetes types in any of the reported rates due to limitations of the physician billing data and the hospital discharge abstract data in identifying type 1 and type 2 diabetes.
• In the latest version of the ICD system (ICD-10-CA) used by hospitals to record the details of discrete hospitalizations, separate codes for type 1 and type 2 diabetes are provided. It is anticipated that as additional ICD-10-CA coded hospital data are accumulated and validated, that it will be possible to analyze and report rates associated with hospitalization stratified by diabetes type. For example, the rate of amputations among those with type 1 diabetes versus those with type 2.
• Using administrative data for surveillance, as in the NDSS, often requires a compromise when trying to identify cases of a disease. It is necessary to balance the possibility of misclassifying people who actually have been diagnosed with diabetes but who have not been captured by the NDSS as a diabetes case (false-negatives) with the reverse where people do not have diabetes but have been captured by the NDSS using the case criteria (false-positives). Validation studies have indicated that the NDSS case criteria minimize both false-negatives and false-positives in order to depict a relatively accurate picture of diagnosed diabetes in Canada. Additionally, there are some people who have not been diagnosed with diabetes, but in fact have the disease. Estimates for the number of people in this category are outside the scope of the NDSS.

3. Nunavut was unable to provide the 2008 data submission for this report.
4. From this point forward, diabetes refers to the NDSS case definition for diagnosed diabetes.