The prevalence of Type 2 diabetes rises with age (Figure 4.3), with prevalence rates being highest among 65-74 year old men and women aged 75 years and over (Australian Institute of Health and Welfare 2002). In 2004-05, almost 700,000 people (3.5% of the population, excluding those with gestational diabetes) had medically diagnosed diabetes mellitus), similar to the 2001 NHS age standardised figures (3.0%) (Australian Bureau of Statistics 2006). A further 56,300 people reported high blood or urine sugar levels, but had not been formally diagnosed. As many cases remain undetected, these prevalence rates are likely underestimate the true prevalence of these conditions. The majority of people with diabetes had Type 2 diabetes(83%), whilst 13% reported Type 1 diabetes and 4% reported diabetes but did not know which type. Among those aged 65 years and over with diabetes, 27% also had one or more circulatory problem.
Prevalence tends to be higher amongst those from CLDB groups, although data collection methods limits accurate information on rates other than across broad population groups (Thow and Waters 2005) . The latest edition of ‘Australia’s Health’ (Australian Institute of Health and Welfare 2004) reports higher mortality rates for migrants (apart from those from the UK and Ireland) and more reporting diabetes (35%), with incidence more common in those from the South Pacific Islands, Southern Europe, the Middle East, North Africa and Southern Asia. Type 2 diabetes prevalence is particularly high amongst Indigenous Australians, being their most frequently managed condition in general practice (Australian Institute of Health and Welfare 2004). Indigenous Australians often develop the condition earlier than other Australians and die at younger ages. The age-standardised prevalence of self reported diabetes was 11% amongst Indigenous Australians compared to 3% in the non-indigenous population (Australian Institute of Health and Welfare 2002).
Figure 4.3 Age-specific prevalence rates of Type 2 diabetes among Australians aged 25+, 1999-2000.
Source: Diabetes: Australian facts 2002 (Australian Institute of Health and Welfare 2002)
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The association of physical inactivity with diabetes has been illustrated in cohort studies. A prospective study followed 8633 men without diabetes, aged 30 to 79 years, for six years (Wei, Gibbons et al. 1999). Based on cardiorespiratory fitness, the least fit men (those in the lowest 20% percentile) had a greater risk of developing impaired glucose tolerance and diabetes (OR 1.7, 95% CI 1.1-2.7 and 3.7, 95% CI 2.4-5.8 respectively). The risk was greater in older men. The same research centre followed over a thousand men (mean age 50 years) with type 2 diabetes for an average of 12 years (Wei, Gibbons et al. 2000). Physical activity was measured using a maximal exercise test and baseline self reported activity. Adjustments were made for baseline CVD, family history of CVD, fasting plasma glucose, hypercholesterolaemia, hypertension, overweight and smoking. Across age categories, the least fit men were more likely to have died (adjusted RR 2.1, 95% CI 1.5-2.9). Similarly, men categorised as inactive were at significantly increased risk (adjusted RR 1.7, 95% CI 1.2-2.3).
Diabetes prevention and managementPhysical activity in conjunction with dietary changes confers benefits in prevention of diabetes amongst high-risk individuals. The US Diabetes Prevention Program was a multi-centre diet and exercise trial of over 3000 adults with impaired glucose tolerance, 20% of whom were 60 years or older (Diabetes Prevention Program Research Group 2002). The intensive lifestyle intervention employed was significantly more effective than the drug metformin (58% versus 31%). The unique impact of physical activity cannot be determined from the study’s design. The risk reduction was marked, with a 50-60% risk reduction (Diabetes Prevention Program Research Group 2002).
A meta-analysis of controlled trials demonstrated that regular physical activity increases insulin sensitivity and improves glucose tolerance across a range of CLDB groups (Boule, Haddad et al. 2001). A range of interventions have been trialled to prevent, reduce or delay the long term complications of diabetes. Those applicable to older people with diabetes are discussed in Chapter 9.
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