What is type 2 diabetes?
Type 2 diabetes is a condition in which blood sugar (glucose) is elevated because of a combination of an inability to produce enough insulin — the hormone that moves glucose from the bloodstream into cells — and cells becoming resistant to insulin's effects, or both.
The result is that glucose builds up in the blood rather than being used for energy. Over time, persistently high blood sugar can damage blood vessels and nerves throughout the body, leading to serious complications if left unmanaged.
Type 2 diabetes is the most common form of diabetes, accounting for around 85 to 90 per cent of all cases in Australia.
What causes type 2 diabetes?
Type 2 diabetes develops through a combination of genetic and lifestyle factors. Having a family history of the condition increases your risk, but lifestyle plays a significant role — particularly carrying excess weight, especially around the abdomen, being physically inactive and eating a diet high in processed foods and refined carbohydrates.
Other risk factors include age (the risk of developing type 2 diabetes rises with increasing age), having had gestational diabetes during pregnancy, and belonging to certain ethnic groups including South Asian, East Asian, Aboriginal and Torres Strait Islander, Pacific Islander and Māori communities, who have higher rates of the condition.
Importantly, type 2 diabetes often develops gradually, with a period of "prediabetes" — where blood sugar is higher than normal but not yet high enough to be diagnosed as diabetes — that can last for years without obvious symptoms.
What are the symptoms?
Many people with type 2 diabetes have no symptoms at all, particularly in the early stages. When symptoms do appear, they can include increased thirst, frequent urination, fatigue, blurred vision, slow-healing wounds and frequent infections.
Because symptoms are often subtle or absent, type 2 diabetes is frequently diagnosed through routine blood tests — which is why regular health checks are important, particularly for people with known risk factors.
What are the complications?
Unmanaged type 2 diabetes significantly increases the risk of serious health complications. These include cardiovascular disease — heart attack and stroke — which remain the leading cause of death in people with type 2 diabetes. Other complications include kidney disease, nerve damage (diabetic neuropathy), eye disease that can lead to vision loss (diabetic retinopathy) and foot problems that in serious cases can require amputation.
The good news is that with effective management, the risk of developing these complications can be substantially reduced.
How is type 2 diabetes managed?
Type 2 diabetes is managed through a combination of lifestyle changes and, for many people, medication. Eating a balanced diet, being physically active, maintaining a healthy weight and not smoking are all central to good diabetes management — and for some people, particularly in the earlier stages, these changes alone can bring blood sugar back to near-normal levels.
When lifestyle changes aren't sufficient, a range of medications are available — including metformin, SGLT2 inhibitors, GLP-1 receptor agonists and others — that help lower blood sugar, protect the heart and kidneys, and in some cases support weight loss. Some people with type 2 diabetes will also need insulin.
Regular monitoring — including HbA1c blood tests, blood pressure checks, cholesterol management and annual reviews for complications — is an important part of long-term care.
Can type 2 diabetes be reversed?
For some people, yes. Significant weight loss — particularly through very low energy diets or bariatric surgery — can bring blood sugar levels back to the normal range, sometimes for extended periods. This is known as remission rather than a cure, as the underlying susceptibility remains and the condition can return if weight is regained.
Research in this area is advancing rapidly. Early and intensive intervention appears to offer the best chance of achieving remission.
Read our explainer: Type 2 diabetes remission — what does it mean and is it possible for me?