Diabetes in Canada

LONG-TERM COMPLICATIONS OF DIABETES

Canadian data on the complications of diabetes are limited. These complications include

• microvascular complications: retinopathy (eye disease) and nephropathy (kidney disease);
• macrovascular complications: cardiovascular disease, stroke, and
• peripheral vascular disease;
• neuropathy (nervous system disease); and
• foot problems, which can lead to amputation.

  The proportion of people with diabetes in whom these complications develop is not known. However, current data sources provide estimates of the proportion of people who have diabetes and who also have (i) heart disease, (ii) vision problems (not specifically retinopathy), and (iii) kidney failure, for which diabetes is likely to be a contributing cause.

Cardiovascular Disease and Stroke

Approximately 21% of people with diabetes compared with 4% without have heart disease or are suffering the effects of stroke (Figure 21). The greatest difference is in the 35 to 64 age group, in which the overall prevalence is 16.2% among those with diabetes and 3% among those without diabetes.

In the 35 to 64 age group, people with diabetes are six times more likely to have heart disease or stroke as those without diabetes (95% CI 4.7-7.4 among males, 4.6-8.3 among females); in the over 65 age group they are twice as likely to have these complications (95% CI 1.3-2.1 among males; 1.8-2.7 among females).

In general a greater proportion of men with diabetes have heart disease or the effects of stroke than women, except in the over 65 age group, in which the prevalence rates are almost the same (28.1% vs 28.9% among women and men respectively) (Figure 21).

FIGURE 21
Prevalence of heart disease or the effects of stroke,
by diabetes status, gender, and age group -
Canada excluding Territories, 1996/97

* Estimate has high sampling variability.
Notes: The sample sizes in the 12-34 age group with diabetes were too small for percentages to be expressed. Diabetes, heart disease, and the effects of stroke refer to current, self-reported conditions that have been diagnosed by a health professional.
Source: LCDC 1998 - using the National Population Health Survey 1996/97, Health Share File, preliminary release.

The prevalence of diabetes is much higher in the population with heart disease or stroke than the population without these two conditions (15% vs. 3%). In the older age group (65 years and above) this finding still holds, although the difference is no longer as great because of the higher overall prevalence of diabetes in this age group (Figure 22).

FIGURE 22
Prevalence of diabetes among people with and without
heart disease or the effects of stroke, by gender and
age group - Canada excluding Territories, 1996/97

* Estimate should be interpreted with caution due to high sampling variability.
Notes: The sample sizes in the 12-34 age group with diabetes were too small a percentages to be expressed. Diabetes, heart disease, and the effects of stroke refer to current, self-reported chronic conditions that have been diagnosed by a health professional.
Source: LCDC 1998 - using the National Population Health Survey 1996/97, Health Share File, preliminary release.

Vision Problems

People with diabetes in the over 65 age group report significantly higher rates of vision problems than do people without diabetes in this age group. These include significantly higher rates of

• cataracts (21.9% vs. 14.1%, p < 0.001),
  
• vision problems that cannot be corrected (problems seeing near or far objects, or total vision loss) (9% vs. 5%, p < 0.001), and
  
• glaucoma (7% vs. 5%, p < 0.05).

Kidney Failure

Statistics from the Canadian Organ Replacement Register (CORR) Annual Report 1998⁽²²⁾ indicate an increase in the proportion of patients with newly diagnosed kidney failure who also have diabetes, from 16% in 1981 to 28% in 1996. According to CORR data, there were 3,340 people with diabetes as of December, 1996 who were receiving treatment for end-stage renal disease, also known as kidney failure.

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