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Diabetes mellitus is a chronic condition in which the body is deficient in producing or using insulin. Untreated, people with diabetes have high blood glucose levels while their tissues lack nourishment. Diabetes can cause diseases of the eyes, kidneys, nerves and cardiovascular system, which can lead to a reduced quality of life and premature death. Type 2 diabetes, the most common form, has increased in prevalence since the 1980s, and further increases in obesity and physically inactive lifestyles, and the ageing of the population, have the potential to continue this increase.
Diabetes has been among conditions of concern to Australian health ministers for some time and continues to be a focus of the Council of Australian Governments' broader commitment to reducing the prevalence of avoidable chronic diseases and their risk factors. (Endnote 1, Endnote 2) Internationally, there are fears that an epidemic of diabetes will follow changes in diet and lifestyle, and population ageing, in developing countries. (Endnote 3)
Data sources and definitions used in this article.
In 2004–05, close to 700,000 people, or 3.6% of the population, reported they had diabetes. This was substantially higher than the 404,000 people, or 2.4% of the population, reporting it in 1995 (after age standardising the rate to adjust for age differences). Some of this increase could reflect increased diagnosis.
The most common type of diabetes is referred to as type 2 and is a degenerative condition in which the body tissue becomes resistant to insulin. In 2004–05, 83% of people with diabetes reported that they had this type. Type 2 most often develops in middle or older age and being overweight or physically inactive are important risk factors for this condition. Of those with type 2 in 2004–05, 81% had been aged 45 years or over when diagnosed. Most of the increase in the prevalence of diabetes since 1995 is due to an increase in type 2.
The less common type of diabetes is referred to as type 1 and is an autoimmune disease in which the body attacks and destroys the insulin producing cells. It has a relatively sudden onset and may arise in childhood, youth or later in life. At present there is no known way to reduce the risk of developing this disease. In 2004–05, 13% of people with diabetes reported they had type 1. More than half (56%) had been diagnosed when aged under 45 years, including 24% diagnosed in childhood (under 15 years). The proportion of the population reporting type 1 remained the same over the period (0.5%) but there are some indications from other data sources of an increase in prevalence among children. (Endnote 5)
In addition to the 700,000 people who reported that they currently had diabetes, an additional 81,000 people reported that they had at some time been told by a doctor or a nurse that they had diabetes, but also reported that they did not currently have the condition. About 72% of these people had been told they had type 2 and most of the remainder did not know the type.
PEOPLE WITH DIABETES
VARIATION IN PREVALENCE
In 2004–05, the proportion of the population with diabetes increased with age from less than half a percent of those aged under 25 years to 14% of those aged 65 years and over. A higher proportion of males than females had diabetes (4.0% compared with 3.2%), reflecting their higher rate of type 2 (3.4% compared to 2.6%). A similar proportion of males and females reported type 1 (0.5% compared with 0.4%).
There is interest in which groups in the population have higher rates of diabetes. In order to examine this variation, the following data are age standardised to adjust for differences in age structure between groups.
Health status often varies by socioeconomic status. In 2004–05, people who lived in local areas rated as the most disadvantaged (based on census data on residents' income, occupation, education and so on) had higher rates of many long term conditions including diabetes. (Endnote 6) The prevalence of diabetes was 2.4% of the population in the least disadvantaged areas and increased with increasing disadvantage of area to 5.5% for people in the most disadvantaged areas.
Diabetes and high blood sugar combined was 3.4 times as prevalent among Aboriginal and Torres Strait Islander people than among non-Indigenous people. Indigenous people living in remote areas of Australia had a rate of these combined conditions about twice that of Indigenous people living in non-remote areas. (Diabetes is often referred to colloquially as blood sugar in remote Indigenous communities, and a combined rate is used to compare the Indigenous and non-Indigenous populations.) See Australian Social Trends 2007, Selected chronic conditions among Aboriginal and Torres Strait Islander peoples.
Prevalence also varied by birthplace. Of birthplace groups which could be examined, diabetes was least prevalent among people born in Northwest Europe (2.8%) and most prevalent among people born in Southern and Central Asia (9%). Such variation can reflect differences in the prevalence of risk factors, but ethnicity is also considered to be a risk factor for diabetes, independent of other factors. (Endnote 7)
DIABETES PREVALENCE(a) BY RELATIVE DISADVANTAGE OF AREA — 2004–05
Being overweight is a recognised risk factor for type 2 diabetes. People may lose weight for health reasons after being diagnosed with diabetes. Nevertheless in 2004–05, the proportion of people who had diabetes increased from 2.8% of people who were of normal weight to 14% of those in the most overweight category. Between 1995 and 2004–05, it became more common to be overweight, with overweight or obese people increasing from 44% to 52% of the population aged 15 years and over. The obese category increased fastest, from 12% to 17%. (For more information see Australian Social Trends 2007, Overweight and obesity)
Lack of exercise is also a risk factor for type 2 and in 2004–05, 5.1% of people who were sedentary in their leisure time had diabetes, compared with 4.2% of people who exercised at a low level, 3.7% of those who exercised at a moderate level and 2.7% of those who exercised at a high level. People who were sedentary in their leisure time made up 34% of the population aged 15 years and over in both 1995 and 2004–05.
People with hypertension are more likely than others to develop type 2 diabetes. This may be because diabetes and hypertension share risk factors such as physical inactivity and overweight. The same proportion of the population reported they had hypertension in 1995 and 2004–05 (11%).
Gestational diabetes is a temporary form of diabetes experienced by about 3%–8% of pregnant women. Women who have had this condition are at increased risk of later developing type 2. In 2004–05, 101,600 women (who had not subsequently developed another type of diabetes) reported that they had gestational diabetes or currently had it.
Some people have impaired glucose metabolism but not in the range that warrants a diagnosis of type 2 diabetes. These people are at higher risk of developing type 2 diabetes than other people, although lifestyle changes could often reduce this risk. An Australian study estimated that in 1999–2000, based on medical tests, as much as 16% of the population aged 25 years and over (or 2 million people) had impaired glucose metabolism, mostly undiagnosed. (Endnote 4)
DIABETES PREVALENCE(a) BY BODY MASS INDEX(b) — 2004–05
HEALTH OF PEOPLE WITH DIABETES
A person's perception of their own general health status is considered a useful measure of their current condition. More than twice as many people with diabetes aged 15 years and over assessed their own health as fair or poor compared with people without diabetes (40% and 15% respectively). While over a quarter of people with diabetes assessed their health as excellent or very good (27%), this compared with 57% of people without diabetes. People with diabetes aged 18 years and over were also more likely to have very high levels of psychological distress than those without diabetes (8% compared with 4%).
SELF-ASSESSED HEALTH STATUS(a) — 2004–05
Type 2 diabetes shares risk factors with cardiovascular disease. Also, over time, both types of diabetes can affect the large and small blood vessels. Diabetic small vessel damage can cause eye disease, renal disease, and nerve damage, while large vessel damage can lead to hypertension and cardiovascular disease. In 2004–05, people with diabetes aged 45 years and over were 1.9 times more likely than people without diabetes of the same age to have hypertension and 2.2 times more likely to have a heart, stroke or vascular condition. They were also more than twice as likely to have high cholesterol (which increases the risk of cardiovascular disease) than people without diabetes of that age.
Of people with diabetes aged 45 years and over, 15% reported that they had a sight problem due to diabetes (33% of those with type 1 and 13% of people with type 2). People with diabetes were 2.3 times as likely to have glaucoma as people without diabetes, 1.6 times more likely to have cataracts and 1.7 times more likely to have complete or partial blindness.
According to medical research, about 30% of people with type 1 diabetes and perhaps as many as 40% of those with type 2 diabetes may eventually develop kidney disease. (Endnote 8) In 2004–05, people aged 45 years and over with diabetes were 1.6 times more likely to have a urinary system disease or non-circulatory fluid retention problems than people without diabetes.
Nerve and blood vessel damage can leave people with diabetes at risk of developing infections in their extremities. People with diabetes aged 45 years and over were close to four times more likely than those without diabetes to have had an amputation, although this was uncommon for both groups. A study based on hospital data in the late 1990s found that on average around 2,600 lower limb amputations due to diabetes and its complications took place per year, with people aged 65–79 years making up the largest group of patients. (Endnote 9)
Diabetes and disability
In 2003, around half of people reporting diabetes in the Survey of Disability, Ageing and Carers had a disability (357,000 people). Of these, 24% reported diabetes as the condition that caused them most problems (80,000 people). Of the close to 150,000 people aged 15–64 years with diabetes and disability, 45% reported being permanently unable to work (65,500 people) and in total, 82% reported some kind of restriction in employment.
PEOPLE AGED 45 YEARS AND OVER: DIABETES AND OTHER CONDITIONS(a) — 2004–05
Managing diabetes involves trying to keep blood glucose within safe levels while ensuring tissues can take up glucose from the blood. This often involves a routine of taking pharmaceuticals and controlling the timing and amount of food that is consumed. In 2004–05, people with diabetes reported in the NHS on the actions they had taken to manage diabetes in the previous two weeks. About 80% of people with each type of diabetes had followed a changed eating pattern or diet because of the condition. Over two-thirds of people with diabetes took medication for the condition including almost all people reporting type 1 diabetes (97%) and 64% of those reporting type 2.
Both physical activity and losing weight may benefit some people with diabetes by reducing cardiovascular risk and assisting the body's use of glucose. In 2004–05, 19% of those with type 1 and 31% of those with type 2 reported that they had exercised most days in the previous two weeks because of diabetes. However, based on amount and type of activity, 45% of people with diabetes aged 15 years and over would be considered sedentary in their leisure time and 32% exercised at a low level. The majority of people with diabetes aged 15 years and over were overweight (73%) including 37% who were obese. Around 9% of people reporting type 1 diabetes and 19% of people reporting type 2 also reported losing weight as part of managing diabetes during the previous 2 weeks.
As people with diabetes are at increased risk of cardiovascular disease, actions which increase risk further, such as smoking, are best avoided. In 2004–05, 12% of adults with diabetes were current daily smokers, while 44% were ex-smokers. These rates were broadly consistent with the smoking and quitting habits of middle to older age groups, which contain most people with diabetes, although people with diabetes were slightly more likely to have given up smoking.
Treating and monitoring unhealthy blood fats and hypertension in addition to maintaining safe blood glucose levels has been shown to delay and reduce the onset of associated conditions in people with diabetes, although this tight control is not necessarily achievable for all patients. (Endnote 10) Of the 318,000 people with diabetes and hypertension, 77% were taking medication commonly used to treat hypertension. About 77% of the 214,000 people with diabetes and high cholesterol were taking medication commonly used to reduce high cholesterol.
Using health services
In 2004–05, almost one-third of people with diabetes had been hospitalised in the previous 12 months (31%) including 45% of people with type 1. In the 2 weeks prior to interview, about half of people with each type of diabetes had consulted a doctor and one in twenty had used outpatient services. This health service use was not necessarily related to diabetes and the level of use partly reflects the older age profile of people with diabetes. That said, on an age-standardised basis, people with diabetes were 4.9 times more likely to have visited outpatients, 2.2 times more likely to have been hospitalised and 1.6 times more likely to have seen a doctor than people without diabetes.
In 2004–05, administrative data show 67,700 hospital episodes ('separations') due to diabetes, accounting for 1.0% of hospital episodes. The number of hospital episodes due to diabetes increased by 31% between 2000–01 and 2004–05, mainly due to an increase in episodes due to type 2.
According to a survey of general practitioners, in 2004–05 diabetes was the fourth most common chronic condition managed by general practitioners and accounted for 3.2 per 100 patient encounters. (Endnote 10)
PEOPLE WITH DIABETES: MANAGING DIABETES AND OTHER HEALTH RELATED ACTIONS(a) — 2004–05
HOSPITAL USE DUE TO DIABETES(a)
The total health system costs of diabetes were estimated as $0.8 billion or 1.6% of national expenditure on diseases in 2000–01. Expenses for hospital admitted services ($231m) and prescription pharmaceuticals ($221m) were the two sectors with the highest costs. Diabetes was 15th highest when around 200 disease groups were ranked by health system costs. These costs do not include the often serious conditions associated with diabetes, such as kidney and cardiovascular disease. For example, in 2004, diabetic nephropathy was for the first time the most common cause of end stage kidney failure (i.e. where patients required dialysis or transplant to live). It was the primary diagnosis for 30% of new patients and a further 12% also had diabetes. (Endnote 12)
ALLOCATED RECURRENT HEALTH EXPENDITURE — 2000–01
In 2004, there were 3,599 deaths with diabetes mellitus as the underlying cause of death. Despite the increase in diabetes prevalence, the age standardised death rate from this disease has remained fairly stable since 1997 and was 17 deaths per 100,000 persons in 2004. The rate for men was higher than that for women (21 deaths per 100,000 persons compared with 13.8 per 100,000).
On average, there were 4.2 conditions listed on the death certificates of people for whom diabetes mellitus was the underlying cause of death in 2004. This compared to an average of 3.1 for all deaths. Most commonly, the other causes were ischaemic heart disease (recorded on 52% of certificates where diabetes was the underlying cause), renal failure (25%), cerebrovascular disease (23%) and heart failure (19%). For every death with diabetes as an underlying cause, there were 3.3 deaths with diabetes as an associated cause: giving a total of 11,700 deaths with diabetes as either an underlying or associated cause.
1 Department of Health and Ageing, Health priorities, DoHA, viewed 25 May 2006, http://www.health.gov.au/internet/wcms/publishing.nsf/Content/Health+Priorities-1.
2 Council of Australian Governments, 14 July 2006 Communique, COAG, viewed 10 October 2006, http://www.coag.gov.au/meetings/140706/index.htm.
3 World Health Organisation, Diabetes: The cost of diabetes, WHO, viewed 10 October 2006, http://www.who.int/mediacentre/factsheets/fs236/en.
4 Dunstan D, Zimmet P, Welborn, T et al. 2001, 'Diabesity and Associated Disorders in Australia – 2000, the Accelerating Epidemic', The Australian Diabetes, Obesity and Lifestyle Study (AusDiab), International Diabetes Institute, Melbourne.
5 Australian Institute of Health and Welfare 2006, Australia's health 2006, cat. no. AUS 73, AIHW, Canberra.
6 Australian Bureau of Statistics 2003, Information Paper: Census of Population and Housing - Socio-Economic Indexes for Areas, Australia, 2001, cat. no. 2039.0, ABS, Canberra.
7 Shaw, JE and Chisolm, DJ 2003, 'Epidemiology and prevention of type 2 diabetes and the metabolic syndrome', Medical Journal of Australia, vol. 179, no. 7, pp. 379–383.
8 National Kidney Foundation 2006, 'Kidney disease of diabetes', viewed 1 November 2006,
9 Payne, CP 2000, 'Diabetes-related lower limb amputations in Australia', Medical Journal of Australia, vol. 173, no. 7, pp. 352–354.
10 Bryant, W, Greenfield, JR, Chisolm, DJ and Campbell, LV 2006, 'Diabetes Guidelines: easier to preach than to practise?', Medical Journal of Australia, vol. 185, no. 6, pp. 305–309.
11 Britt, H, Miller, GC, Knox, S et al. 2005, General practice activity in Australia 2004–05, cat. no. GEP 18, AIHW, Canberra.
12 ANZDATA Registry Report 2005, Australia and New Zealand Dialysis and Transplant Registry, Adelaide, South Australia.
Data sources and definitions
This article draws mainly on data from the 2004–05 ABS National Health Survey (NHS). The survey scope was people in private dwellings. Data are self-reported estimates of people with diagnosed diabetes. Type 2 diabetes can go undiagnosed and an Australian study estimated that in 1999–2000, 7.5% of the population aged 25 years and over had diabetes mellitus, twice as many as had been diagnosed. (Endnote 4)
People with diabetes in the NHS are people who reported they currently had diabetes mellitus type 1 or type 2 or did not know the type they had. People who reported having gestational diabetes only, or diabetes insipidus (a rare form of diabetes unrelated to diabetes mellitus), were excluded.
In this article most rates based on NHS data are age standardised. Age standardising adjusts for differences which are due to the different age profiles of the populations being compared. In this case, it adjusts for differences between people with and without diabetes in 2004–05, between different groups in the population in 2004–05, and between the Australian population in 1995, 2001 and 2004–05.
International concern about diabetes
The World Health Organisation (WHO) is concerned that an epidemic of diabetes may follow changes in lifestyle and diet, and population ageing, in developing countries. WHO projects that the number of people with diabetes worldwide will increase from an estimated 177 million in 2000 to 300 million by 2025. It estimates that around 4 million deaths worldwide in 2000 (9% of total deaths) related to the presence of diabetes. Indicative of the debate and research surrounding the true prevalence of diabetes, this replaces an earlier WHO estimate of 800,000 deaths each year being due to diabetes. Affording the costs of treating diabetes will prove a particular challenge to low and middle income nations. For example, a WHO analysis of health expenditure in the Western Pacific region estimated that 16% of hospital expenditure was on people with diabetes. (Endnote 3)
Mortality data are based on the medical certificate of cause of death filed when deaths are registered with State and Territory Registrars.
Underlying cause of death is as identified by the doctor or coroner on the medical certificate of cause of death.
Associated cause of death is any health condition other than the underlying cause of death listed on the medical certificate of cause of death.