What is diabetes?

• Diabetes is a chronic condition, marked by high levels of glucose in the blood. It is caused by deficient production of the hormone insulin, or resistance to its action.

• In Type 1 diabetes the body does not produce any insulin at all

• In Type 2 diabetes (the most common) the body produces insufficient insulin or is resistant to its action; in Type 2 diabetes a person may have the disease for many years before the symptoms become apparent

• Gestational diabetes can occur during pregnancy and increases the risk of developing diabetes later in life

• Diabetes-related complications include coronary heart disease, stroke, peripheral vascular disease, blindness, kidney disease, amputation of limbs and impotence. It can also lead to pregnancy-related complications, both for the mother and the foetus or new-born baby.

Size of the problem

• Diabetes prevalence (diagnosed and undiagnosed) of approximately 250,000 Victorians (almost 1 in 4 of the population aged 25+)

• It is estimated that half of all cases of diabetes mellitus in Victoria are undiagnosed

• Diabetes is directly responsible for over 3% of the total disease burden in Victoria (20,000 DALYs per annum out of 600,000)

• Diabetes is responsible for 5% of disease burden (30,000 DALYs) if direct sequelae (such as renal, eye, neurological and peripheral vascular complications) are included

• Diabetes is the cause of about 3% of premature mortality in Victoria (about 10,000 YLL), most often because of ischaemic heart disease, stroke and renal disease

• Type 1 diabetes (insulin-dependent/juvenile onset) comprises about 12% of all cases of diabetes and Type 2 diabetes (non-insulin-dependent/later onset) about 88% of cases

• Gestational diabetes occurs during pregnancy in about 4%-6% of women not previously known to have diabetes, while other forms of diabetes are less common

Historical trends

• The estimate of the number of adults in Australia with diabetes has trebled since 1981

• It is unlikely that the increase in this period can be solely attributed to the ageing population

• The trend in the prevalence of overweight people (an important risk factor for diabetes) is unfavourable (increasing steadily since the 1980s) with about 63% of adult males and 48% of adult females currently overweight

• Diabetes death rates in males are now higher than in 1950 but lower than their peak in 1968

• In females, the diabetes death rates are now about half the level they were in 1950, and well below that for males

International comparisons

• Significant variation exists in the incidence of Type 1 diabetes internationally, with Australia among the countries with a relatively high incidence

• The proportion of people with Type 2 diabetes is much higher in countries in Asia and the Pacific Islands

Projections

• Diabetes is projected to increase at a faster rate in men than in women, the disease burden doubling from 3% to 6% in men and increasing from 3% to 4% in women (from 1996 to 2016)

Special populations

Diabetes mellitus prevalence is higher in:

• Older people:

  • Advancing age is associated with diabetes due to increasing insulin resistance in older people, and the risk of complications also increases with age

• Indigenous Australians:
  • The prevalence of Type 2 diabetes in Indigenous Australians is among the highest in the world
  • For Indigenous Australians aged 25-54 it is 7-8 times higher than for non-Indigenous people

  • Among those aged 55 and over it is more than twice as high as non-Indigenous people

• Rural areas:
  • The difference in diabetes prevalence between metropolitan, rural and remote areas is not significant
  • Hospital admission rates for complications of diabetes are 25% higher in rural Victoria compared to Metropolitan areas
  • These conditions are considered to be preventable through good management, and may be indicative of a problem with access to primary health care in rural areas

  • There is a twelve-fold variation in admission rates for diabetes complications across local areas in Victoria (Primary Care Partnership catchment areas)

• Socioeconomically disadvantaged groups:

  • Diabetes is almost two-and-a-half times as high among the lowest socio-economic category compared to the highest category

• People from some culturally and linguistically diverse (CALD) background:
  • Higher prevalence among people born in southern Europe, Asian Indians, South Pacific Islanders, Chinese and some Arab populations
  • Evidence exists that CALD background may be a barrier to accessing relevant services

Evidence-based interventions

• Increasing commitment to primary prevention across major health issues including diabetes (e.g. focus on obesity, nutrition and physical activity)

• Increasing rates of early detection by establishing processes for raising awareness of diabetes in the community and health professionals and increasing skills in testing, diagnosis and follow-up

• Improving capacity to provide effective and accessible routine and specialist care services for people with diabetes, either through GPs or outpatient care centres

• Streamlining and coordination of approaches to best practice, quality of care and management of complications

Diabetes risk factors

1. Downstream (biomedical/physiological)
   • excess weight, particularly obesity
   • impaired glucose tolerance
   • release of stress hormone (e.g. cortisol)

   • "Metabolic syndrome"

2. Midstream (individual/demographic/behavioural)
   • Behavioural: Poor diet; physical inactivity; tobacco use; alcohol misuse
   • Psychosocial: Low relative position in social hierarchy; Low perceived control; isolation; lack of social support; loss of meaning or purpose
   • Demographic/socio-economic: Low SES; Indigenous; CALD; Rural/remote residence

   • Health services: Lack of preventative services; lack of effective and culturally appropriate primary health services

3. Upstream (physical/social environmental conditions; broader determinants of health)
   • Social capital
   • Civic engagement
   • Income inequality
   • Government policies

Related health issue - The metabolic syndrome

The World Health Organization has classified a specific clustering of risk factors as the Metabolic Syndrome (Syndrome X). Insulin resistance is thought to be the underlying defect in this syndrome. In addition to insulin resistance, a person with the Metabolic Syndrome will usually have two or more of the following: glucose intolerance (impaired glucose tolerance or diabetes), dyslipidaemia, high blood pressure, central obesity and microalbuminuria. The syndrome greatly increases a person's risk of developing Type 2 diabetes or cardiovascular disease. The social gradient in prevalence of the metabolic syndrome is consistent with the 'allostatic load' hypothesis* which links the psychosocial environment to physical disease via neuroendocrine pathways. (Source: WHO 1999. Definition, diagnosis and classification of diabetes me13 June, 2006ation of diabetes mellitus. Geneva: Department of Noncommunicable Disease Surveillance. WHO.)

* McEwen, B.S. (1998). Protective and damaging effects of stress mediators. N. Engl. J. Med. 338, 171-9

Reference