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Diabetes is a group of disorders and the 10th leading cause of deaths in Australia. There are four clinical classes of diabetes:1
- Type 1 diabetes – Results from ß-cell destruction due to an autoimmune process usually leading to insulin deficiency
- Type 2 diabetes – Results from a progressive insulin secretory defect on the background of insulin resistance
- Gestational diabetes mellitus (GDM) – Defined as glucose intolerance with onset or first recognition during pregnancy
- Other specific types of diabetes (Section 3.3. Impaired fasting glucose or impaired glucose tolerance) – Due to other causes such as genetic defects in ß-cell function, genetic defects in insulin action, diseases of the exocrine pancreas (eg cystic fibrosis), and drug-induced or chemical-induced causes (eg treatment of human immunodeficiency virus/acquired immune deficiency syndrome [HIV/ AIDS] or after organ transplantation)
Type 2 diabetes is a largely preventable, chronic and progressive medical condition that results from two major metabolic dysfunctions: insulin resistance and then pancreatic islet cell dysfunction causing a relative insulin deficiency. In an individual, these occur due to modifiable lifestyle-related risk factors interacting with nonmodifiable and genetic risk factors.
The relative insulin deficiency leads to chronic hyperglycaemia and multiple disturbances in carbohydrate, protein and fat metabolism including:
- ß-islet cell dysfunction, failure of response to insulin signalling and increased islet cell apoptosis
- α-cell dysfunction with elevated glucagon levels
- resultant disorders of hepatic gluconeogenesis and insulin resistance with elevated glucose production
- muscle cell insulin resistance with decreased glucose uptake
- kidney adaptation with altered gluconeogenesis and increased glucose reabsorption via increased sodium glucose transporter protein activity
- diminished incretin hormonal production or resistance
- maladaptive cerebral hormonal responses to insulin and appetite
- increased lipolysis with elevated free fatty acids.