While mortality from diabetes declines in Canada, the income-related mortality gap increases

Canadian Medical Association JournalDec 22 2009

While mortality from diabetes has declined in Canada, the income-related mortality gap is increasing, with lower income groups faring worse than higher income groups, according to a new study http://www.cmaj.ca/embargo/cmaj090495.pdf in CMAJ (Canadian Medical Association Journal) www.cmaj.ca.

Globally, diabetes is associated with a two-fold increase in mortality, with most of those deaths due to cardiovascular issues. Survival for people with diabetes has improved over the last 10 years, partly because of better diabetes care and a reduction in cardiovascular events.

The study looked at data from Ontario, Canada from 1995 to 2006. The number of Ontarians aged 30 years or older with diabetes rose 130% while the non diabetes population in Ontario rose 17% over the same period. Death rates were significantly higher in men than in women and in people aged 65 and older compared with younger people.

Age- and sex-standardized mortality fell by 33% across all income groups but the higher income groups experienced a larger decline in mortality than the lowest income group (36% versus 31%). In people aged 30-64 years, there was a more than 40% widening in the rate ratio (from 1.1 to 1.6) between the poorest versus the richest group.

"Our findings suggest that improvements in diabetes outcomes may be lagging in the poorer segments of the diabetic population," write Dr. Lorraine Lipscombe of Women's College Hospital in Toronto and coauthors.

They suggest several reasons for these findings. Increasing costs of medications may be limiting access and compromising care for people who cannot afford medications. In people aged 65 and over, income had a much smaller effect on mortality as drug costs are subsidized for this age group. Lower health literacy in poorer patients may be hindering their ability to follow complicated medical routines.

Changing demographics in Ontario, especially due to immigration, may also be a factor. Between 1996 and 2006, 37% of immigrants were South Asian, a group susceptible to diabetes and cardiovascular complications. New immigrants often have lower incomes than more established residents.

"Our study highlights the urgent need to address barriers to adequate diabetes care in low-income populations, to stem the rising burden of diabetes among poorer people," state the authors.