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By Professor Paul Zimmet AM,MB,BS,MD,PhD,FRACP,FRCP (London),FAFPHM
Background
Diabetes mellitus is recognised as a serious global health problem often resulting in substantial morbidity and mortality, primarily from cardiovascular complications, eye and kidney diseases and limb amputations, and will be one of the major health problems facing Australia in the 21st century (1)
Classification of diabetes
The existence of at least 2 clinical types of diabetes was first demonstrated convincingly 50 years ago by a distinguished Melbourne physician/biochemist, Joseph Bornstein. He developed an insulin bio-assay and showed there was no measurable insulin in the blood of juvenile-onset diabetics. This important finding preceded, by a decade, the Nobel Prize winning discovery of a more sophisticated technology in the insulin radio-immunoassay which only confirmed Bornstein s earlier observations. Diabetes is a collection of closely related diseases. The classification is based on differences in causation, natural history and clinical presentation. The two major categories of diabetes are:
Type 1 diabetes (formerly known as insulin-dependent diabetes mellitus) is one of the most common childhood disease in developed nations and constitutes about 10% of all persons with diabetes in Australia. Type 1 diabetes is believed to be caused by an auto-immune process which results in a slow destruction of pancreatic islet beta-cells by the body s own immune system. The presentation is usually in young people but may occur at any age and is usually a dramatic onset of:
- Extreme thirst and dry mouth
- Frequency of urination
- Sudden weight loss
- Blurred vision
- Infections eg skin boils, urinary tract infection
Type 2 diabetes (formerly known as non-insulin dependent diabetes mellitus) constitutes about 85% of all diabetes in Australia. It is mainly a lifestyle disorder highly associated with obesity and overweight, lack of exercise and unhealthy eating practices. There may be no symptoms at first for up to 5 years so early detection in people at high risk is warranted. Otherwise, there may be mild and gradual symptoms eg:
- Tiredness
- Mild thirst and frequency of urination
- Unexplained weight loss
- Infections
High risk groups for diabetes include:
- People who are obese or have high blood pressure or existing heart disease;
- People with a strong family history of diabetes;
- Aboriginal and Torres Strait Islanders;
- Asians and Pacific Islanders;
- Women with a past history of gestational diabetes;
- The elderly.
A global and national perspective
World-wide, diabetes is becoming epidemic. Recently, in collaboration with World Health Organization (WHO) in Geneva, the International Diabetes Institute produced new global predictions of the number of people with diabetes for various countries for the year 2025(unpublished). It was estimated that in 2000 there were approximately 160 million people with diabetes in the world. This will climb to over 280 million people by the year 2025, the majority of them with Type 2 diabetes. For Australia there will be an estimated 1.23 million persons with diabetes by the year 2010. The estimated number of Australians with diabetes in 2000 was 940,000 (Figure 1) with a dramatic rise evident in the number of cases of diabetes over the last two decades.
Changes in society over recent decades have impacted on lifestyle leading to lower levels of physical activity and unfavorable changes in our diet with consequent increase in obesity(3). These factors, and the ageing of the Australian population have led to high levels of morbidity from a number of chronic diseases which contribute greatly to national health costs. Diabetes mellitus and cardiovascular disease are two of these conditions(1; 3). As a result they have been included by the Federal, State and Territory governments in the six National Health Priority Areas which also include cancer, trauma, asthma and mental health.
Diabetes is recognised as:
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the second most common cause for commencing renal dialysis,
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the most common cause of blindness in people under the age of 60 years,
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the most common cause of non-traumatic lower limb amputation, and
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one of the most common chronic diseases in children (4).
The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) study
Accurate, representative and recent prevalence data for diabetes in Australia were unavailable or inadequate prior to the 1999-2000 Australian Diabetes, Obesity and Lifestyle Study (AusDiab) - the first national study to provide estimates of the number of people with diabetes (based on blood tests) and its public health and societal impact. This important initiative was an integral component of the National Diabetes Strategy that resulted from the vision and commitment of the Federal Minister, Dr Michael Wooldridge, to tackle the mounting problem of diabetes and its complications in Australia.
AusDiab was a nationally representative study which surveyed participants in each state and the Northern Territory of Australia, involving 11,247 participants over 2 years of testing. Details relating to the methods of this study have been published elsewhere(5). The key findings of the study were the prevalence of diabetes was 7.4% in the Australian population aged 25 years and older - 8.0 % for males and 6.8% for females. The prevalence of diabetes rose from 2.4% in people 35 to 44 years to 23.0% in those 75 years and over.
- For every known case of diabetes, there was another undiagnosed case.
- There are approximately 940,000 people over the age of 25 years with diabetes in Australia.
- The number of people with diabetes has trebled since a broadly based blood survey was undertaken in 1981.
- The prevalence of impaired glucose metabolism (either impaired glucose tolerance (IGT), impaired fasting glycaemia (IFG), or diabetes) of the survey population was 23.7% - 25.3 % for males and 22.2 % for females
ALMOST 1 IN 4 AUSTRALIANS 25 YEARS AND OVER HAS EITHER DIABETES OR A CONDITION OF IMPAIRED GLUCOSE METABOLISM. THIS CONDITION IS ASSOCIATED WITH SUBSTANTIALLY INCREASED IMMEDIATE RISK OF HEART DISEASE AS WELL AS INCREASED RISK OF DIABETES IN THE FUTURE (6)
1. McCarty DJ, Zimmet P, Dalton A, Segal L, Welborn TA: The rise and rise of diabetes in Australia, 1996: A review of statistics, trends and costs. Canberra, International Diabetes Institute & Diabetes Australia, 1996
2. Australian Bureau of Statistics: Causes of Death, Australia, 1996. Canberra, Australian Bureau of Statistics, 1997
3. Australian Institute of Health and Welfare: Australia's Health 1998: the sixth biennial health report of the Australian Institute of Health and Welfare. Canberra, AIHW, 1998
4. Colagiuri S, Colagiuri R, Ward J: National Diabetes Strategy and Implementation Plan. Canberra, Diabetes Australia, 1998
5. Dunstan D, Zimmet P, Welborn T, Cameron A, Shaw J, deCourten M, Jolley D, McCarty D, On behalf of the AusDiab Steering Committee: The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) - methods and response rates. Diabetes Research and Clinical Practice 57:119-129, 2002
6. Dunstan DW, Zimmet PZ, Welborn TA, De Courten MP, Cameron AJ, Sicree RA, Dwyer T, Colagiuri S, Jolley D, Knuiman M, Atkins R, Shaw JE: The rising prevalence of diabetes and impaired glucose tolerance: the Australian Diabetes, Obesity and Lifestyle Study. Diabetes Care 25:829-834., 2002
Updated Nov 2002
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