1. SECTIONS:
2. preface & acknowledgements
3. genetics at a glance
4. contacts, support & testing
5. testing & pregnancy
6. newborn screening
7. cancer in the family
8. cardiovascular conditions
9. chromosomal conditions
10. clotting & bleeding conditions
11. cystic fibrosis
12. diabetes
13. fragile X syndrome and other causes of developmental delay
14. haemoglobinopathies
15. hereditary haemochromatosis
16. neurofibromatosis
17. neurological conditions
18. psychiatric conditions
19. genetics in practice
20. emerging genetic technologies
21. glossary

Type 2 diabetes

 

Clinical features

1. This form of diabetes most often occurs after the age of 40 so it has been referred to as maturity-onset
   diabetes.

 

Genetics

1. Genetic predisposition for type 2 diabetes is stronger than for type 1, but the magnitude of genetic
   contribution is unknown and probably involves several genes.
2. Recent research has identified that several polymorphisms in the hepatocyte nuclear factor 4 alpha
   (HNF-4α) gene is associated with increased susceptibility to type 2 diabetes by about 30%.
3. Genetic testing is still in the research phase.

 

Prevalence

1. 7.5% of the Australian population aged 25 years and older have diabetes, 8.0% of males and 7.0% of females. In people 75 years and over, 23.6% has diabetes.
2. Type 2 diabetes accounts for more than 85% of people with diabetes in Australia.
3. Increasing incidence of diabetes parallels the increase incidence of obesity.
4. The frequency of the condition, and the most common age of onset, is different in different populations.
   The condition is epidemic in some countries.
5. The lowest prevalences are seen in less developed countries (up to 2% in China and Africa).
6. The highest prevalence can be found in certain ethic groups around the world:
7. Greater than 50% prevalence in Australian Aboriginal people.
8. Increased prevalences of diabetes in Pima Indians in the USA, South Sea Islanders and Pacific
   Islanders, all of whom develop type 2 diabetes early in their lives and quite severely.

 

Management

1. For at-risk family members, diet and exercise may postpone the onset of the condition, or diabetes may
   not develop at all.

 

Implications for family members

1. Risk that relatives of a family member with type 2 diabetes will also develop the condition has been
   estimated from observations of families with a history of the condition, not genetic testing (Table 2).

 

Table 2

Approximate genetic risks in type 2 diabetes mellitus (European data)

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