Diabetes in Canada

MODIFIABLE RISK FACTORS FOR DIABETES

The NPHS 1996/97 provides the most recent, although limited, information on the main modifiable risk factors for Type 2 diabetes: obesity and physical inactivity. Trend data on these factors derive from the NPHS 1994/95 and 1996/97 and the General Social Surveys 1985 and 1991. Income inadequacy, smoking, and hypertension (high blood pressure) are additional modifiable risk factors for diabetes and its complications for which we have data.

Obesity

The association between obesity and diabetes is supported in the literature, as cohort studies have indicated that obesity is an independent risk factor for diabetes⁽¹⁹⁾. Diabetes can also exacerbate obesity over time, in that the complications of diabetes can limit physical activity, and intensive treatment for diabetes often results in weight gain.

• Obesity in the General Population

  A greater proportion of males than females in the population aged *20-64 are above the acceptable weight range (Body Mass Index 25) (59% vs. 37% respectively). According to the NPHS definition of "overweight" (Body Mass Index 27), 35% of males and 23% of females are overweight (Table 15). Note that this definition differs from that of the U.S. National Institutes of Health, which defines "overweight" as a Body Mass Index of 25. (People under *20 years of age, those who were pregnant, and those over 65 were not assessed for weight status in the NPHS.)

  TABLE 15 Percentage distribution of weight status among those aged *20-64, by sex - Canada excluding Territories, 1996/97
  Weight status	% distribution by sex		Total
  	Males	Females
  Insufficient	---	---	8.2
  Acceptable	38.1	48.9	43.3
  Some excess	24.6	13.8*	19.3
  Overweight	34.6	23.4	29.2
  *Estimate has high sampling variability. Notes: --- = sample size is too small to be expressed as a percent age. "Insufficient" = BMI < 20. "Acceptable" = BMI 20-24.9. "Some excess weight" = BMI 25-27. "Overweight" = BMI > 27. BMI= Body Mass Index. Weight and height were self reported. People under *20 yrs of age, pregnant, or over 65 were not assessed for weight status. Source: LCDC 1998 - using National Population Health Survey 1996/97, Health Share File, preliminary release.

  *(Prior to August 23, 1999, this read 18.)

  This finding of higher levels of obesity among males may partially explain the higher prevalence of diabetes among males than females (see Table 2).

  There is some evidence that obesity has been increasing since 1991, although comparisons among surveys with differing methodologies must be interpreted with caution (Figure 19).The cause of the apparent increase in obesity is unknown, as there have been no longitudinal national surveys of caloric intake in Canada.

• FIGURE 19
  Risk factor for diabetes: Trends in weight status
  among the population aged 20-64 years - Canada
  excluding Territories, 1991-1996/97*
  

  

  * Comparisons between surveys with differing methodologies should be interpreted with caution
  
  Notes: Standard weight was calculated from Body Mass Index (BMI) scores. BMI = weight (kg)/squared height (meters squared). BMI< 20 = "Insufficient" weight in NPHS (equivalent to GSS 91 category "possibly underweight"). BMI= 20-24.9 was "acceptable". BMI= 25-27 was "some excess weight" in NPHS (equivalent to "possibly overweight" in GSS 91). BMI > 27 was "some excess weight" in NPHS (equivalent to "possibly overweight" in GSS 91). BMI > 27 was"overweight". Measurement of BMI for GSS 85 was not comparable to GSS 91 and NPHS 94/96. Height and weight were self-reported.
  
  Source: LCDC 1998 - using General Social Survey (GSS) 1991, National Population Health Survey (NPHS)1994/95 Health file, and National Population Health Survey 1996/97, Health Share file, preliminary release.

• Obesity by Diabetes Status

  A substantially greater proportion of people with, than without, diabetes in the 35 to 64 age group are overweight (Body Mass Index 27) (59% vs. 32%, Table 16).

  TABLE 16 Weight status among people aged 35-64 years, by diabetes status - Canada excluding Territories, 1996/97
  Diabetes status	Not  overweight %	Overweight %
  With diabetes	41.3	58.7
  Without diabetes	67.7	32.3
  Total	66.9	33.2
  Notes: "Not Overweight" = Body Mass Index (BMI) < 27 which includes the range of NPHS categories from insuf ficient", "accept able", to "some excess" weight. "Over weight" = BMI > 27. BMI = weight (kg)/squared height (m). Diabetes, height and weight were self-reported. Source: LCDC 1998 - using National Population Health Survey 1996/97, Health Share File, preliminary release.

  The trend for increasing obesity is also evident in the longitudinal data from the NPHS 1996. Both those with,and without, diabetes showed a trend to increasing obesity (Table 17).

  TABLE 17 Cohort-based trends in percentage distribution of weight status, by diabetes status and age group - Canada excluding Territories, 1994/95-1996/97
  Age group in 1994	Diabetes status	Weight status
  		1994/95		1996/97
  		Not overweight %	Overweight %	Not overweight %	Overweight %
  35-64	With diabetes '94/96	43.3*	56.7*	40.6*	59.4
  	Without diabetes '94/96	67.3	32.7	65.7	34.3
  * Estimate has high sampling variability. Notes: Not Overweight = Body Mass Index [weight (kg)/squared height (m2)]< 27; includes categories some excess weight, acceptable weight, and insufficient weight. Diabetes, height and weight are self-reported. Overweight = Body Mass Index [weight (kg)/squared height (m)] > 27. With diabetes 94/96 = respondents with self-reported diabetes in the 1994 & 1996 NPHS. Without diabetes 94/96 = respondents with out self-reported diabetes in the 1994 & 1996 NPHS Source: LCDC 1998 - using the National Population Health Survey, Longitudinal Share File, preliminary release.

  Physical Inactivity

• Physical Inactivity in the General Population Over 50% of both males and females in the general population are physically inactive, females more so than males (60% vs. 54% respectively) (Table 18).

  TABLE 18 Percentage distribution of physical activity status in the population aged 12 and over, by sex - Canada excluding Territories, 1996/97
  Physical activity status	% distribution
  	Males	Females	Total
  Active	23.85	17.53	20.61
  Moderate	22.32	22.98	22.65
  Inactive	53.83	59.49	56.73
  Notes: Measurements of energy expenditures: "Active" = average 3+ cal/kg per day. "Moderate" = average 1.5-2.9/kcal/kg per day. "Inactive" = 1.5 kcal/kg per day. Source: LCDC 1998 - using National Population Health Survey 1996/97, Health Share File, preliminary release.

  Canadians in general appear to have become somewhat less sedentary from 1985 to 1996; however, differing methodologies among surveys in terms of how physical activity level is measured make any conclusions tentative at best (Figure 20).

  FIGURE 20
  Risk factor for diabetes: Trends in physical inactivity across
  surveys* - Canada excluding Territories, 1985-1996/97
  

  

  * physical inactivity measurement differs across surveys but is consistent within surveys across years.
  Notes: GSS defined "sedentary" as = < 500 kcal/wk of energy expenditure. NPHS defined "inactive" as < 1.5 kcal/kg/week of energy expenditure (or < 735 kcal/wk for an average (70Kg) man). Note that according to NPHS criteria some respondents who were not classified as sedentary in the GSS would have been classified as physically inactive in the NPHS. GSS respondents were aged 15+ years, and NPHS respondents were aged 12+ years.
  
  Source: LCDC 1998 - using General Social Survey (GSS) 1985 and 1991, National Population Health Surveys, Health File (1994/95), Health Share File (1996/97), preliminary release.

• Physical Inactivity by Diabetes Status Levels of physical inactivity are similar for those with and without diabetes in the 35 to 64 age group (63% and 61% respectively), but higher in those with diabetes in the over-65 age group (76% vs. 64%) (Table 19).

  TABLE 19 Physical activity level, by age group and diabetes status - Canada excluding Territories, 1996/97
  Age group	Diabetes status	Physical activity level
  		%
  		Active	Inactive
  35 - 64	With diabetes	36.7	63.3
  	Without diabetes	38.9	61.1
  	All	38.8	61.2
  65+	With diabetes	24.4	75.6
  	Without diabetes	35.8	64.2
  	All	34.6	65.4
  Notes: Sample sizes in the 12-34 age group with diabetes are too small to be expressed as percentages. Respondents classified by the NPHS 96 physical activity index (measurement of energy expenditure) as "active" (aver age 3+ kcal/kg/day) or "moderate" (average 1.5- 2.9 kcal/kg/day) were counted in the Active category. Respondents classified as "inactive" (< 1.5 kcal/kg per day) were counted in the Inactive category. Diabetes is self-reported. Source: LCDC 1998 - using National Population Health Survey 1996/97, Health Share File, preliminary release.

  Although physical inactivity is a risk factor for diabetes, it is also a risk factor for complications such as cardiovascular disease. Therefore, the high proportion of people with diabetes who are physically inactive is a matter of great concern.

  Income Inadequacy

  For people aged over 35 years, those with diabetes are more likely than those without diabetes to have lower levels of income adequacy (calculated as a relation between household size and total income before deductions) (Table 20). The biggest difference is in the 35 to 64 age group, in which 48% of people with diabetes compared with 38% without diabetes are in the lower two quartiles of income adequacy. This association is an important factor in the prevention and control of diabetes. The cost of diabetes treatment supplies is covered by provincial/territorial programs to a variable extent across Canada.

  TABLE 20 Income adequacy, by diabetes status and age group - Canada    excluding Territories, 1996/97.
  Age group	Diabetes status	Income adequacy group
  		%
  		Lowest	Lower middle	Upper middle	Highest
  12 - 34	With diabetes	---	35.7*	26.7*	---
  	Without diabetes	16.5	30.2	29.3	14.0
  35 - 64	With diabetes	20.8	27.0	40.2	12.1
  	Without diabetes	12.2	26.0	42.9	19.0
  65+	With diabetes	23.0	48.2	21.2	7.7
  	Without diabetes	24.5	42.1	28.4	5.0
  Population (12+yrs)	With diabetes	22.3	37.1	30.8	9.9
  	Without diabetes	15.4	29.7	39.7	15.3
  Notes: *Estimate should be interpreted with caution because of high sampling variability. --- = sample size is too small to be expressed. Diabetes was self-reported. Income refers to total income from all sources before taxes or deductions. Income adequacy was assessed as follows: Lowest" = 1-4 persons and less than $10,000; 5+ persons and less than $15,000. Lower middle" = 1-2 persons and $10,000-14,999; 3-4 persons and $10,000-$19,999; 5 or more per sons and $15,000-$29,000. Middle" = 1-2 persons and $15,000-$29,999; 3-4 persons and $20,000-$39,000; 5 or more persons and $30,000-$59,999. Upper mid dle" = 1-2 per sons and $30,000 - $59,999; 3-4 persons and $40,000-$79,999; 5 or more persons and $60,000-$79,999. Highest" = 1-2 persons and $60,000 or more; 3 persons or more and $80,000 or more. Source: LCDC 1998 - using National Population Health Survey 1996/97, Health Share File, preliminary release.