Mortality trends in patients with and without diabetes in Ontario, Canada and the UK from 1996 to 2009: a population-based study

Aims/Hypothesis — To determine the contemporary rate ratio of mortality and changes over time in patients with versus without diabetes.

Methods — Annual age and sex-adjusted mortality rates were compared for adults (>20 years) with and without diabetes in Ontario, Canada and the United Kingdom (UK) from January 1996 to December 2009 using the THIN and Ontario databases. The total number of individuals evaluated increased from 8,757,772 in 1996 to 12,696,305 in 2009.

Results — The excess risk of mortality for diabetic patients in both cohorts was significantly lower during later versus earlier years of the follow-up period (1996-2009). In Ontario the diabetes mortality rate ratio decreased from 1.90 (1.86, 1.94) in 1996 to 1.51 (1.48, 1.54) in 2009, and in THIN from 2.14 (1.97, 2.32) to 1.65 (95% CI 1.57, 1.72) respectively. In Ontario and THIN, the mortality rate ratios among diabetic patients in 2009 were 1.16 (1.13, 1.19) and 1.24 (1.17, 1.30) for ages 65-74 years and 1.23 (1.20, 1.26) and 1.25 (1.18, 1.31) for ages over 74 years, respectively. Corresponding rate ratios in Ontario and THIN were 1.94 (1.84, 2.04) and 2.23 (1.98, 2.50) for ages 45-64 years, and 1.70 (1.63, 1.78) and 1.79 (1.63, 1.95) for ages 20-44 years.

Conclusions/Interpretation — The excess risk of mortality in patients with versus without diabetes has decreased over time in both Canada and the UK. This decline in excess risk of mortality may be in part due to earlier detection and higher prevalence of early diabetes, as well as improvements in diabetes care.