What is diabetes?

Diabetes is a chronic condition marked by high levels of glucose in the blood. It is caused either by the inability to produce insulin (a hormone made by the pancreas to keep blood glucose levels in range) or by the body not being able to use insulin effectively, or both.

Diabetes increases the risk of health complications, including heart disease, stroke, kidney disease, blindness and lower limb amputation. It is frequently associated with other chronic health conditions, such as cardiovascular disease and chronic kidney disease.

Type 1 diabetes

Type 1 diabetes is a lifelong autoimmune disease that can be diagnosed at any age but most commonly develops in people aged under 30. The exact cause is unknown, but it is believed to be the result of an interaction of genetic and environmental factors. A person with type 1 diabetes needs insulin replacement to survive and, except in cases where a pancreatic or islet cell transplant occurs, insulin will be required every day for the rest of their life. People with type 1 diabetes must also maintain a careful balance of diet, exercise, glucose management and insulin intake.

Type 2 diabetes

Type 2 diabetes is a condition in which the body becomes resistant to the normal effects of insulin and gradually loses the capacity to produce enough insulin in the pancreas. The condition has strong genetic and family-related (non-modifiable) risk factors and is also often associated with modifiable risk factors. The exact genetic causes of type 2 diabetes are unknown. People may be able to significantly slow or even halt the progression of the condition through changes to diet and increasing the amount of physical activity (Diabetes Australia 2022).

Gestational diabetes 

Gestational diabetes occurs when higher than optimal blood glucose is diagnosed in pregnancy. This generally occurs in the second or third trimester of pregnancy, among women who have not previously been diagnosed with other forms of diabetes and can result in complications for mother and baby. While gestational diabetes may resolve after the baby is born, it can recur in later pregnancies and greatly increases the risk, both for the mother and the baby, of developing type 2 diabetes later in life. Some women can manage their gestational diabetes by changes to diet and physical activity, while others require oral hypoglycaemic (blood glucose lowering) medications, insulin therapy, or both.

Other diabetes

‘Other’ diabetes represents a name for less common forms of diabetes resulting from a range of different health conditions or circumstances. This includes conditions affecting the pancreas and endocrine system, viral infections, genetic syndromes and in some cases, diabetes triggered from medications needed to manage or treat another health condition. ‘Other’ diabetes may now also refer to new-onset diabetes associated with COVID-19 infection and treatment for the virus (Sathish et al. 2021).


Pre-diabetes is a condition characterised by elevated blood glucose, but not meeting the diagnostic criteria for diabetes. It includes impaired fasting glucose (IFG) where blood glucose levels are higher during a fasted state, impaired glucose tolerance (IGT) where glucose levels are higher than normal, and elevated glycated haemoglobin (HbA1c) which indicates the average blood glucose levels over the past 2–3 months. People with pre-diabetes are at increased risk of developing diabetes and cardiovascular disease.


Diabetes Australia (2022) Type 2 diabetes, Diabetes Australia website, accessed 15 March 2022.

Sathish T, Kapoor N, Cao Y, Tapp RJ and Zimmet P (2021) Proportion of newly diagnosed diabetes in COVID-19 patients: a systematic review and meta-analysis, Diabetes, Obesity & Metabolism, 23(3):870-4, doi:10.1111/dom.14269.