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Diabetes - symptoms, diagnosis, treatment

Over 200 000 New Zealanders have diagnosed diabetes (diabetes mellitus).  It is estimated that another 100,000 have diabetes that has not been diagnosed.  Symptoms can include excessive urination and thirst, fatigue and nausea. Treatment aims to maintain healthy blood glucose levels and to prevent serious health complications.
In New Zealand Type 2 diabetes is increasing rapidly and in some regions is considered to have reached epidemic proportions.   Maori and Pacific Island New Zealanders are more than three times more likely to develop diabetes than most other New Zealanders. Rates of diabetes are also high among Asian New Zealanders. Other risk factors for developing diabetes include: obesity; family history; high blood pressure and cholesterol levels; little or no exercise; pregnancy; women who have had a large baby (>4000g birth weight) and/or a history of gestational diabetes; and being over 40 years of age.

What is diabetes?

During digestion most foods are converted into a sugar called glucose.  Glucose is a simple sugar that is the main fuel source for the body.  Once food has been converted into glucose, it moves into the bloodstream where it is circulated around the body.  It then passes into the body's cells to be used as energy. 
For glucose to pass from the bloodstream into the cells, insulin is required.  Insulin is a hormone produced in the pancreas - a large gland that sits behind the stomach.  Specialised cells in the pancreas, called beta cells, automatically produce the correct amounts of insulin to move the glucose into the cells. Insulin production rises and falls throughout the day in response to the body's needs.  However, in people with diabetes there is a problem with the production of insulin or with the body's ability to use the insulin.
Diabetes is a metabolic disorder, which means a problem with the process by which food is digested and used as energy by the body.  It is a chronic (long-term) condition characterised by high levels of glucose in the blood (hyperglycaemia).  If not treated it can cause long-term complications such as coronary heart disease, kidney damage, stroke, circulatory problems and damaged vision.

Type1, Type 2, gestational

There are three main types of diabetes - Type 1, Type 2 and gestational – typically associated with different circumstances.
Type 1 diabetes:
In Type 1 diabetes the pancreas produces little or no insulin.  It has also been referred to as "juvenile onset diabetes" or "insulin dependent diabetes mellitus" (IDDM).  While it is usually diagnosed between the ages of 7 - 12 years, it can occur at any age.  Approximately 10% of all people with diabetes have Type 1.  Type 1 diabetes is thought to occur as the result of an autoimmune reaction. During an autoimmune reaction the body's immune system attacks the body's own healthy cells and tissues.  In Type 1 diabetes, it is thought that the body attacks and destroys the specialised insulin-producing beta cells in the pancreas, making them incapable of producing insulin.  It is not known what causes this autoimmune reaction to occur, but it is believed that certain viruses or environmental factors, as well as genetic factors are involved. There is also some evidence to suggest that dietary factors and stress play a part in the development of the condition.
Type 2 diabetes:
In Type 2 diabetes the pancreas still produces insulin, however it may not produce enough insulin to meet the body's needs.  There is also a problem with the ability of the cells in the body to utilise the insulin (insulin resistance) - particularly the cells in the liver, fat and muscles.  Type 2 diabetes has also been referred to as "adult onset diabetes" or "non-insulin dependent diabetes mellitus" (NIDDM).  People of any age can develop it and some people with Type 2 diabetes require insulin injections.  It is the most common form of diabetes affecting approximately 90% of all people with diabetes.  There is a strong hereditary component to Type 2 diabetes.  It is also related very strongly to obesity - the greater the degree of obesity, the greater the risk of developing the condition.  Age is also an important factor, with the condition most commonly occurring after the age of 40 years.  It is thought that as people age, beta cells become less efficient and the cells in the body become less able to use the insulin made by the pancreas.
Gestational diabetes:
This is an uncommon form of diabetes that can occur during pregnancy.  During the course of pregnancy approximately 2 - 4% of women will develop gestational diabetes, however the condition usually disappears after the pregnancy. It can manifest as either Type 1 or Type 2 diabetes.  Women who have had gestational diabetes are at greater risk of developing Type 2 diabetes later in life.  Gestational diabetes is thought to occur as a result of hormonal changes during pregnancy in women who are genetically predisposed to develop diabetes.
Other causes:

Diabetes can also occur as the result of: 

  • Medications - eg: prednisone (a steroid medication) and some diuretics (water tablets), which can increase the chances of developing diabetes by increasing insulin resistance.
  • Certain medical conditions - eg: diseases of the pancreas (eg: chronic pancreatitis) and some disorders of the hormone-producing endocrine glands (eg: Cushings' syndrome).
  • Trauma or surgery - eg: injury to the pancreas or surgical removal of the pancreas.
  • Some genetic disorders eg: Down's syndrome, Turner's syndrome and some muscular dystrophies.

Signs and symptoms

The onset of symptoms in Type 1 diabetes is typically quite sudden and symptoms can be severe.  However the symptoms of Type 2 diabetes tend to manifest gradually, so much so that they may go unnoticed.  When hyperglycaemia occurs, the body tries to get rid of the excess glucose by excreting it in the urine.  This increases urine output and can lead to dehydration.  At the same time the body's cells are starved of the glucose energy they need. The combination of these factors produces the common symptoms of diabetes.  These may include: 

  • Weight loss
  • Excessive thirst
  • Excessive urination
  • Fatigue
  • Nausea
  • Irritability
  • Yeast infections
  • Blurry vision
  • Skin wounds or infections that are slow to heal
  • Numbness and tingling in the feet


If diabetes is suspected it is important to see a doctor promptly so that an accurate diagnosis can be made and appropriate treatment given. Early diagnosis and treatment will help to prevent diabetes-related complications.  To assist with diagnosis, blood tests are used to measure the glucose levels in the blood.  These include:
Fasting blood glucose test:
A sample of blood is taken to measure the blood glucose levels in the blood after the person has not eaten for several hours.  This is usually performed in the morning, before breakfast.  It is the most common blood test used to assist with diagnosis.
Random blood glucose test:
A sample of blood is taken to measure the glucose levels in the blood - regardless of when the person last ate.   The acceptable range for glucose in the blood is 4.0 - 8.0mmol/L (mmol of glucose per litre of blood) before a meal.  A diagnosis of diabetes can usually be made if there are classical symptoms of the condition and blood glucose levels of greater than 11mmol/L for a random blood glucose test, or greater than 7mmol for a fasting blood glucose test.
HbA1c test
A blood test called the haemoglobin A1c (HbA1c) assay is often used to indicate a person's average blood glucose levels over a period of time.  As well as being a diagnostic tool, this test is useful in monitoring the progress of the condition and the effectiveness of treatment.  To further confirm the diagnosis of diabetes, a glucose tolerance test (GTT) may be recommended.  This is a very sensitive test in which the person drinks a measured quantity of glucose after having a sample of blood taken.  Further blood samples are taken at fixed intervals in the two hours following the glucose drink.  The results will indicate how the body responds to increased glucose levels in the blood.  In a person who does not have diabetes, the blood glucose levels will rise after the drink, then slowly fall as insulin is produced to metabolise it.  In a person with diabetes, the levels of glucose in the blood will remain high for a long time, or they may be very slow to fall.
Urine tests may also be done and will demonstrate high levels of glucose.  They are not used in isolation in the diagnosis of diabetes, as the results can be misleading.
If diabetes is suspected the doctor may also check the eyes, kidneys and heart to make sure there has been no damage due to diabetes.


While diabetes cannot be cured, it can be controlled.  The aim of treatment is to maintain healthy blood glucose levels (ie: between 4.0 mmol/L and 8.0 mmol/L) and to prevent diabetic complications.  This will normally involve balancing lifestyle factors (eg: diet and exercise) and medications.
In order for a person to effectively control the diabetes, it is important that they are treated and monitored by a doctor.  Usually this is the person's GP, however other healthcare professionals will be included in a wider "diabetes management" team to assist with ongoing education, monitoring and treatment.  This team may include a diabetes specialist (endocrinologist), diabetes nurse educator, dietitian, foot care specialist (podiatrist) and an eye specialist (ophthalmologist).
Health promotion, early detection, knowledge of the condition and effective monitoring of blood glucose levels are also considered to be important.  Therefore, as part of the nation-wide management of diabetes all people in New Zealand with the condition are entitled to a free diabetes check with their GP or practice nurse once a year.
Generally it is recommended that foods containing refined sugars be avoided. This includes foods such as chocolate, jam, soft drinks, sweet biscuits, cakes, pastries and some fruit juices.  Natural carbohydrates, which can be converted to energy, are recommended.  This includes foods such as fruit, vegetables, wholemeal bread and cereals.  The diet should also be low in fat and high in dietary fibre.  Alcohol contains a lot of sugar so intake should be minimised. Having a regular eating pattern is also important as this helps to keep blood glucose levels balanced.   In some cases, having snacks between meals may be recommended.  Again this helps to balance blood glucose levels.   It is recommended that people with diabetes seek dietary advice from a dietitian and that they follow an individualised food plan. 
Regular exercise is important in maintaining balanced blood glucose levels.  Exercise also helps to maintain a healthy body weight and control high blood pressure and high blood cholesterol levels.  This in turn helps to reduce the risk of related health conditions such as cardio-vascular disease (heart attacks and strokes).  It should be remembered however that excessive and/or prolonged exercise can cause the blood glucose levels to drop too low.  It is therefore recommended that any exercise undertaken is regular and moderate.
Other Lifestyle Factors
When the body is stressed, the blood glucose levels are more difficult to control.  It is therefore important that stress is adequately managed.  It is recommended that people with diabetes do not smoke.  Smoking plays a part in increasing the risk of developing many diabetic complications.  Illness can also make blood glucose levels more difficult to control.  If blood glucose levels become unstable due to illness, it is important to consult a doctor - particularly if vomiting occurs.

People with Type 2 diabetes may not be able to adequately control their blood glucose levels through diet, exercise and lifestyle changes alone.  Therefore, in many cases diabetic tablets are required.  There are a variety of tablets available, which work in different ways.  These include:  

  • Tablets to increase insulin output from the pancreas eg: Glipizide, Glibenclamide
  • Tablets to reduce insulin resistance eg: Metformin
  • Tablets that stop the absorption of carbohydrates from the bowel eg: Acarbose
In people with Type 1 diabetes and in some people with Type 2 diabetes, insulin injections are required.  There are a number of different types of insulin available that vary in the duration of time they are effective. Some are short-acting; meaning they are absorbed quickly by the body and are effective for a short period of time. Others are long-acting; meaning they are absorbed more slowly by the body and are effective for a longer period of time. Often a combination of different types of insulin is required.   Insulin is injected under the skin of the abdomen or thigh and can be administered by using a disposable syringe and needle, or a preloaded insulin “pen”. Insulin can also be administered by a pre-programmed insulin pump. An insulin pump is a small battery powered device into which insulin can be a loaded. The insulin is pumped into the abdomen via a thin plastic tube connected to a very thin plastic needle that is secured under the skin.   It is important that the person is trained in how to correctly administer the insulin.  This training is usually given by a diabetes nurse educator.  The amount of insulin required, and how often it is to be administered will vary according to the needs of the individual and the glucose levels in the blood.
To enable blood glucose levels to be tested, a droplet of blood is obtained from a small finger prick test and is measured on a special testing strip.  The results will help to determine how much medication is required, how much exercise can be undertaken and what foods should be eaten.  This simple home test needs to be performed regularly, in some cases up to several times per day.  It is important to follow the guidelines given by the treating doctor as to how often they should be done. 


Diabetes can cause both acute (sudden onset) and chronic (long-term) complications.  Complications will be worsened by diabetes that is poorly managed.
This is a situation where there are abnormally low levels of glucose in the blood.  It can occur when excessive amounts of diabetic medications have been given, when not enough food has been eaten, or when too much exercise has been undertaken.  Because cells rely on glucose for fuel in order to function, hypoglycaemia can affect the proper functioning of the cells - particularly the cells in the nervous system. This can lead to initial symptoms such as nervousness, dizziness, weakness, confusion, blurred vision and tremors.   The first signs of hypoglycaemia must be treated quickly in order to prevent symptoms becoming severe.  This involves eating or drinking something sugary eg: orange juice, glucose tablets.  If left untreated, hypoglycaemia can cause seizures and coma.  This situation requires urgent treatment in hospital.
Some people with Type 1 diabetes can develop a complication called diabetic ketoacidosis. Ketoacidosis develops when the body doesn't have enough insulin to break down glucose and use it as fuel, so it breaks down fat to use for fuel instead. When fat is broken down acids called ketones are produced. If too much fat is broken down at any one time, excessive amounts of ketones may be released, causing the blood to become acidic.  This can lead to symptoms such as vomiting, headache, drowsiness, a rapid pulse and abdominal pain. There may also be an acetone smell on the person’s breath.  If left untreated, and in severe cases, diabetic ketoacidosis can lead to coma and death. If ketoacidosis is suspected, urgent medical treatment should be sought.
Chronic complications essentially occur as a result of damage to blood vessels.  Diabetes can cause the small blood vessels to weaken and break, and the large blood vessels to harden, narrow and become blocked with fatty deposits (a process known as atheroscerlosis).  The resultant poor circulation, compounded by the fact that people with diabetes are more prone to infections, can lead to various complications.  Chronic diabetic complications occur when diabetes has remained uncontrolled over a period of many years.  However, most of the following complications can be minimised or prevented by good control of the diabetes.
Circulatory problems
Atherosclerosis and damage to the large blood vessels can impede the circulation of blood around the body - particularly affecting to the heart, brain and lower limbs.  This is compounded by the fact that people with diabetes are more prone to high blood pressure and high blood cholesterol levels.   When circulation to the heart is affected (cardiovascular disease) there is an increased risk of angina and heart attack.  When circulation to the brain is affected (cerebrovascular disease) there is an increased risk of stroke.  When circulation to the lower legs is affected it is known as peripheral vascular disease (PVD).  This can cause pain in the lower legs, known medically as claudication.  PVD can also slow the healing of small injuries of the lower legs.  This can lead to the development of infections, ulcers and in some cases, gangrene.  In severe cases, surgery to repair blood vessels or to amputate diseased tissue is required.
Diabetes can damage the nerves - particularly the nerves of the lower legs and sometimes the hands.  The nerve damage can cause symptoms such as decreased sensation, numbness, burning, tingling and pain in the affected area.  When damage to the nerves is caused by diabetes it is referred to as diabetic neuropathy.  Medications to help relieve the pain caused by diabetic neuropathy may be given.  Medications commonly used in the treatment of epilepsy and depression are sometimes used for this purpose.   Decreased sensation in the lower legs can make it difficult for the person to know when an injury occurs.  In order to prevent the complications of diabetic neuropathy, it is important for people with diabetes to take particular care to check their feet regularly, keep them clean and protect them from injury.
In people with diabetes, the many tiny blood vessels in the retina can weaken or break.  This can affect the retina's ability to work properly and can cause blood to leak into the eyeball, clouding the vision.  This process is known as diabetic retinopathy.   Diabetic retinopathy and cataracts do not tend to occur until diabetes has been present for many years.  It is therefore recommended that people with diabetes are screened for these conditions by having their eyes checked every 1 - 2 years by an eye specialist (ophthalmologist).  This allows for early detection and appropriate treatment.
The kidneys filter wastes from the blood and excrete them in the urine.  When the delicate filtering structures and blood vessels within the kidneys are damaged, the kidneys are unable to function effectively and kidney failure can occur.  When this is caused by diabetes it is referred to as diabetic nephropathy.  Diabetes is one of the leading causes of kidney failure in New Zealand.  Severe kidney failure may need to be treated with dialysis and in some cases a kidney transplant (sometimes combined with a pancreas transplant). In New Zealand, over 40% of all patients requiring renal replacement therapy (i.e. dialysis or a kidney transplant) do so because of the damaging effects of diabetes.  The kidneys also play an important role in regulating blood pressure.  Damage caused by diabetes can lead to high blood pressure (hypertension), which in turn can compound the kidney damage.  Medications and/or a low salt diet may be prescribed to treat the high blood pressure.  People with diabetes are also at greater risk of developing urinary tract infections (UTIs).  These can also cause damage to the kidneys if the infection reaches the kidneys themselves.
Teeth and gum problems
People with diabetes are at greater risk of developing infections of the teeth and gums.  It is therefore important that particular care is paid to the health of teeth and gums.  It is also recommended that people with diabetes have regular check-ups with their dentist. 
A side effect of blood vessels damage and the resultant poor circulation can be impotence in men.  This may also be compounded by the treatment for other diabetes-related conditions such as high blood pressure.  If impotence is experienced, it is important to discuss this with a GP or specialist.

Treatment research

While no cure for diabetes is known, research is continuing in order to develop new and more effective management and treatments for the condition.   Some of the areas being researched include: 

  • Alternative ways of delivering insulin that do not involve injections eg: nasal sprays, patches and tablets.
  • Devices that can measure blood glucose levels through the skin rather than having to obtain a finger prick of blood.
  • Transplantation of insulin-producing pig-cells into humans.  This research is controversial and is at an early stage.
  • Bioengineering techniques that may allow researchers to create artificial insulin-producing cells

Further support and information

It is important for people with diabetes to have broad support from areas such as family, partners, healthcare professionals and diabetes support groups.  Information and diabetic supplies can be obtained from Diabetes New Zealand - a nationwide, non-governmental, non-profit, membership organisation.  The aim of the organisation is to support 14,000 members, 39 diabetes societies throughout New Zealand, and health professionals involved with diabetes. It can also provide information on the Diabetes Supply Scheme - which markets diabetes products within New Zealand and distributes educational leaflets and books.
Diabetes New Zealand
Freephone: 0800 DIABETES (0800 342 238) for educational resources and diabetes products.
Freephone 0800 369 636 for membership inquiries
A support and information service aimed at young New Zealanders is:
Diabetes Youth


Anderson, K.N., Anderson, L.E. & Glanze, W.D. (eds.) (2006) Mosby’s medical, nursing, & allied health dictionary (6th ed.) St. Louis: Mosby-Year Book, Inc.
Davidson, A.M., Cumming, A.D., Swainson, C.P. & Turner, N. (1999) Diabetes Mellitus.  In C.Haslett, E.R. Chilvers, J.A.A. Hunter & N.A. Boon (eds.) Davidson’s principles and practice of Medicine (18th ed.) (p472-509) Edinburgh: Churchill Livingstone
Ministry of Health (2002). Diabetes in New Zealand - Models and Forecasts 1996-2011. Ministry of Health (Booklet)
Ministry of Health (2009). Mortality and Demographic Data 2006.  Ministry of Health (Booklet)
Ministry of Health (2011). Diabetes. Ministry of Health. Wellington.
Diabetes New Zealand Inc. (2000) Diabetes - an information guide (Pamphlet).
Last Reviewed - October 2012 


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