Dr Alan Barclay
Overweight, obesity and diabetes are on the up downunder.
The latest results from Australia’s largest population health study, AusDiab, show that rates of diabetes continue to increase around the nation. When AusDiab began in 1999–2000, 8.5% of the adult population 25 and over had diabetes; in 2011–12 that number had increased to 12.0%. As is the case in other parts of the world, rates are higher amongst socially disadvantaged groups.
While by no means the only factor, increasing rates of overweight and obesity are likely partially responsible for the upward trend. Results from Australia’s most recent national health survey show that in 2011–12, 69.7% of men and 55.7% of women 18 and over were overweight or obese, and slightly more men (52% of all cases) have diabetes than women (48% of all cases). Overweight and obesity rates have increased from 56.3% of all adults in 1995.
Of greatest concern is the finding that young adults (25–34 years) are gaining more weight around the middle than any other age group – a 6.6cm increase over the 12-year follow-up period. Increased waist circumference is an independent risk factor for type 2 diabetes, independent of overall weight gain.
The ingenious use of accelerometers and inclinometers enabled AusDiab researchers to compare self-reported physical activity levels with those measured objectively with scientific instruments. Nearly two-thirds of participants were classified as sufficiently active (50 minutes of moderate-to vigorous-intensity physical activity per day) based on their self-reported physical activity. However, on average, participants engaged in 32 minutes of accelerometer-assessed moderate- to vigorous-intensity physical activity per day – a gap of 18 minutes. In other words, people overestimated their moderate-to vigorous-intensity physical activity by more than 50% each day. Arguably the most sobering finding was that on average, participants engaged in 523 minutes (8 hours and 43 minutes) of inclinometer-assessed sitting time per day.
The AusDiab researchers recommended a concerted effort to improve people’s physical activity levels, and perhaps more importantly to decrease their sitting time, to help reduce the rate of type 2 diabetes in Australia. Standing desks discussed in the April 2012 edition of GI News are a practical example of what can be done to help with this in the workplace environment.
A 10% ‘fat tax’ was also recommended. Australia’s current Goods and Services Tax (GST) already acts as a de-facto ‘fat tax’ in Australia as it is not levied on fresh fruit and vegetables or other core foods – only so-called ‘junk foods’ like soft drinks, chips, confectionery and fast foods attract the 10% GST. Overall, the evidence that a ‘fat tax’ will reduce levels of obesity and associated type 2 diabetes is limited. It is also regressive, affecting people from lower socio-economic groups the most. The evidence for the positive effects on dietary behaviours of tax subsidies for healthy foods like fresh fruits and vegetables is far stronger, and will conversely benefit people from lower socio-economic groups the most.
While it may sound like doom and gloom, it’s important to note that the increase in diabetes rates over the past 12 years in Australia are in line with AusDiab’s best case scenario – not worst. Australia's population is aging, and the risk of diabetes increases with age. Also, we are helping people with diagnosed diabetes manage their condition better, so they are living for longer with the condition. So at this point in time, an increase in diabetes prevalence may be seen as somewhat inevitable. The fact that prevalence has increased at a relatively modest rate in line with AusDiabs best case scenario indicates that as a community we must be doing something right to reduce the populations risk overall.
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Dr Alan W Barclay, PhD
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Glycemic Index Foundation (Ltd)
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