Southern Cross Medical Library

Southern Cross Medical Library

Diabetes is when the level of glucose (sugar) in your blood is too high because your body produces insufficient insulin or resists the effects of insulin.

Type 2 diabetes is a life-long variation of the disease and is often associated with being overweight, i.e., having a high body mass index (BMI), but also occurs in people with a low BMI. Symptoms develop gradually and can cause serious health complications over time. The condition can be managed with lifestyle changes and medication.

General information

Diabetes mellitus (commonly referred to as diabetes) is a group of diseases characterised by high blood glucose (blood sugar) levels over a prolonged period of time. This page deals with type 2 diabetes. Other diabetes variations include type 1 diabetes (usually diagnosed in childhood but can occur at any age) and gestational diabetes (where a mother cannot produce enough insulin during pregnancy).

Five percent of adolescent and adult New Zealanders, or approximately 215,000 people, have been diagnosed with diabetes (mostly type 2 diabetes), and many more have the condition but do not yet know it. The condition is more common among Māori, Pasifika, and Asian people than in European New Zealanders.

Type 2 diabetes used to be known as adult-onset diabetes because it most often occurs in adulthood. However, type 2 diabetes is increasingly being diagnosed in children and adolescents, which may be related to an increasing prevalence of obesity.


Type 2 diabetes develops when the body becomes resistant to the effects of insulin and/or when the pancreas stops producing enough insulin. Insulin is a hormone that promotes the uptake of glucose from the blood into cells so that it can be metabolised (broken down) and used by the body as an energy source.

The direct effect of insulin is to lower blood glucose levels. However, when there is insufficient insulin or the body’s cells no longer respond to the effects of insulin, glucose accumulates in the blood leading to high blood glucose levels. High blood glucose levels over a prolonged period of time are associated with serious health complications.

Risk factors

It is not understood why some people develop type 2 diabetes and others do not but certain factors can increase a person’s risk of the developing the condition. These risk factors include:

  • Being overweight
  • Fat distribution, primarily around the abdomen
  • Inactivity
  • Family history (parent or sibling with type 2 diabetes)
  • Ethnicity
  • Age (risk increases with ageing, especially after age 45 years)
  • Prediabetes (when a person’s blood glucose level is slightly higher than normal, but not high enough to be classified as diabetes)
  • Having previously had gestational diabetes
  • Polycystic ovarian syndrome.

Signs and symptoms

Classic symptoms of type 2 diabetes are:

  • Frequent urination (peeing)
  • Excessive thirst or excessive fluid intake
  • Excessive eating or excessive hunger
  • Weight loss.

Other symptoms include:

The signs and symptoms develop gradually. Many people with type 2 diabetes do not have symptoms and so their condition remains undiagnosed, in some cases for many years.


Early diagnosis and treatment are important to help to prevent diabetes-related complications. Diagnosis of type 2 diabetes is primarily based on blood tests, which include:

Random blood glucose test: A blood sample is taken at a random time

Fasting blood glucose test: A blood sample is taken after an overnight fast

Glycosylated haemoglobin (Hb1Ac) test: This blood test is a measure of a person’s average blood glucose level for the past 2–3 months.

If diabetes is suspected a doctor may also check a person’s eyes, kidneys, and heart to make sure there has been no damage due to diabetes.


Type 2 diabetes can easily go unnoticed in its earlier stages but still, over time, cause damage to blood vessels in the body leading to serious health complications including:

  • Heart and blood vessel disease (coronary heart disease)
  • Damage to the nerves (neuropathy)
  • Kidney disease (nephropathy).
  • Visual problems (retinopathy, glaucoma, cataracts)
  • Foot problems (‘diabetic foot’)
  • Hearing impairment
  • Impotence
  • Skin infections (such as cellulitis).

Controlling blood glucose levels so that they stay in their normal healthy range can help to prevent these complications from developing.


It may be possible to manage type 2 diabetes by eating healthy foods, exercising, and maintaining a healthy bodyweight. If these lifestyle changes are not enough to help the body to control its blood glucose level, diabetes medications or insulin therapy may also be needed. The aim of treatment is to maintain healthy blood glucose levels and to eliminate symptoms and prevent diabetes-related complications.


A high-fibre low-fat diet based on fruits, vegetables, and whole grains is recommended. Foods and beverages containing refined sugars should be avoided. Alcohol drinks often contain a lot of sugar and alcohol itself can generate an increase in glucose levels, so intake should be reduced.

Physical activity

Exercise helps to lower blood glucose levels. Regular exercise also helps to maintain a healthy bodyweight and control high blood pressure and high blood cholesterol levels. This in turn helps to reduce the risk of related health conditions such heart attack and stroke. Sitting still (i.e., being sedentary) for long periods is a risk factor for type 2 diabetes, so you should aim to get up regularly and move around for a few minutes. Combining aerobic exercise (e.g., walking, swimming, biking, or running) with resistance exercise (e.g., weightlifting, yoga) is best.

Medications and insulin therapy

Although some people can achieve and maintain a normal blood glucose level with diet and exercise alone, it is likely all people with type 2 diabetes will need medication at some point. Many medications, which work in different ways, are used to treat type 2 diabetes. The best prescription for you will depend on a range of factors. Ensuring healthy blood pressure is important and is likely to be a factor in assessing what medication, or combination of medications, may be appropriate. Early initiation of diabetes medication is associated with reduced long-term complications of type 2 diabetes.

Weight loss surgery

People with type 2 diabetes and who are overweight (BMI - greater than 35) may be eligible for weight-loss surgery (bariatric surgery).

Blood glucose monitoring

Depending on a person’s treatment plan, their blood glucose levels may need to be checked and recorded periodically or, if being treated with insulin, multiple times a day. Many factors can affect blood glucose levels so careful monitoring is the only way to ensure that blood sugar levels remain within their normal range.

Two blood glucose level problems requiring immediate attention are:

  • High blood glucose (hyperglycaemia): Eating too much or not taking enough diabetes medication can result in a blood glucose level that is too high. Signs of hyperglycaemia include frequent urination, increased thirst, dry mouth, blurred vision, fatigue, and nausea. Hyperglycaemia requires adjustment of meal plans, medications, or both.
  • Low blood glucose (hypoglycaemia): Blood glucose levels can drop for many reasons, e.g., skipping a meal, taking too much diabetes medication, or exercising more than usual. Hypoglycaemia is most likely when taking insulin or diabetes medications that promote the secretion of insulin. Signs of hypoglycaemia include sweating, shakiness, weakness, hunger, dizziness, headache, blurred vision, slurred speech, drowsiness, confusion, and potentially seizures. Drinking or eating something sweet/sugary will correct a low blood glucose level.

Further information and support

For further information and support contact your doctor, practice nurse, or any of the following organizations.

Diabetes New Zealand

Freephone: 0800 DIABETES (0800 342 238)

Email: [email protected]


Kids Health



Khardori R. (2020). Medscape drugs and diseases: Type 2 diabetes mellitus (Web Page). New York, NY: WebMD LLC. [Accessed: 27/11/22]

Mayo Clinic Staff (2022). Type 2 diabetes (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. [Accessed: 27/11/22]

Ministry of Health (2022). Annual Data Explorer – Diabetes (diagnosed) 2021/2022 (Web Page). Wellington: New Zealand Ministry of Health.!/explore-indicators [Accessed: 27/11/22]

Morales Pozzo, A.E. (2021). Medscape drugs and diseases: Pediatric type 2 diabetes mellitus (Web Page). New York, NY: WebMD LLC. [Accessed: 27/11/22]

O’Toole, M.T. (Ed.) (2017). Diabetes mellitus. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.

Last Reviewed: November 2022



The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross.