Diabetes mellitus (commonly referred to as diabetes) is a group of diseases characterised by high blood sugar levels over a prolonged period of time. This page deals with type 1 diabetes. Other diabetes variations include:
- Type 2 diabetes – associated with a person being overweight
- Gestational diabetes – where a mother cannot produce enough insulin during pregnancy
Type 1 diabetes accounts for 5-8% of people with diabetes, while type 2 diabetes is much more common, accounting for 85–90% of diabetes cases.
Type 1 diabetes used to be known as juvenile diabetes and most often occurs in childhood, but it can also develop in adults. The condition may affect around one in every 5000 New Zealanders under the age of 15. Type 1 diabetes is more common in New Zealand Europeans than other ethnic groups.
Although the exact cause of type 1 diabetes is unknown, it is generally considered to be an autoimmune condition in which the body's immune system mistakenly attacks and destroys the insulin-producing (islet) cells of the pancreas (a gland that secretes insulin into the blood). Once a critical number of islet cells have been destroyed, the body produces little or no 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. In doing so, insulin lowers the level of glucose in the blood. Without insulin, glucose is not taken up into the cells and blood sugar levels increase potentially causing serious health complications.
Certain factors are associated with an increased risk of developing type 1 diabetes.
Known risk factors for type 1 diabetes include:
- Family history: Having a parent or sibling with type 1 diabetes
- Genetics: The presence of certain genes
- Age: Peak incidence occurs at 4–7 years and at 10–14 years.
Possible risk factors include:
- Exposure to certain viruses, eg: Epstein-Barr virus, coxsackievirus and other enteroviruses, mumps virus
- Early exposure to cow's milk
- Upper respiratory infections early in life.
Signs and symptoms
The signs and symptoms of type 1 diabetes can appear suddenly. The classic symptoms are:
- Excessive or constant thirst
- Frequent urination (peeing)
- Extreme hunger.
Other signs and symptoms include:
- Unexplained weight loss
- Fatigue and weakness
- Blurred vision
- Bedwetting in children
- Vaginal yeast infection.
A doctor should be seen if any of the above signs and symptoms develop, especially the classic symptoms of diabetes.
In the presence of the classic symptoms of diabetes, the following blood tests will confirm a diagnosis of type 1 diabetes:
- Random blood glucose test: A blood sample is taken at a random time. A random blood glucose level of 11.1 mmol/L or higher indicates diabetes
- Fasting blood glucose test: A blood sample is taken after an overnight fast. A fasting blood glucose level of 7 mmol/L or higher on two separate tests indicates diabetes
- Oral glucose tolerance test: A blood sample taken before drinking a mixture of glucose dissolved in water and again 2 hours after. A blood glucose level of 11.1 mmol/L or higher indicates diabetes.
A blood test called the glycosylated haemoglobin (Hb1Ac) test might also be performed. It is a measure of a person’s average blood glucose level over the past 2–3 months. An Hb1Ac level of 6.5% or higher on two separate tests indicates diabetes. The Hb1Ac test is also used to monitor the effect of treatment. It is generally recommended that HbA1C levels should be maintained below 7%.
Blood tests to check for immune system proteins that act against the islet cells and insulin (autoantibodies) may also be done. These tests help to distinguish between type 1 and type 2 diabetes.
Serious complications of type 1 diabetes that develop gradually over many years include:
- Heart and blood vessel damage (cardiovascular disease)
- Damage to the nerves (neuropathy)
- Kidney damage (nephropathy)
- Damage to the eyes (retinopathy)
- Foot problems (‘diabetic foot’)
- Skin and mouth problems, including infections
- Pregnancy complications (for mother and baby).
Maintaining blood glucose levels as close as possible to normal can help to delay or prevent these complications from developing.
Potentially serious complications of type 1 diabetes that can develop suddenly are:
- Diabetic ketoacidosis. This occurs when, in the absence of insulin and hence the inability metabolise glucose, the body uses fat as an alternative fuel source. This results in a build-up of acids in the blood called ketones. High blood ketone levels can be fatal if not corrected with medical treatment. Signs and symptoms include: nausea, vomiting, abdominal pain, and breath that smells sweet/fruity
- Low blood glucose (hypoglycaemia): Blood glucose levels can drop for many reasons, eg: missing a meal, injecting too much insulin, or over-exercising. Signs and symptoms of hypoglycaemia include: sweating, shakiness, weakness, hunger, dizziness, headache, blurred vision, slurred speech, drowsiness, confusion, and possibly seizures. Hypoglycaemia requires immediate attention because if left untreated leads to loss of consciousness. Drinking or eating something sweet/sugary will help to correct a low blood glucose level. Carrying a source of sugar at all times is recommended as is carrying an emergency injection of glucagon, which is a hormone that stimulates the release of sugar into the blood
- High blood glucose (hyperglycaemia): Eating too much or not taking enough insulin can result in a blood glucose level that is too high. Signs and symptoms of hyperglycaemia include: frequent urination, increased thirst, dry mouth, blurred vision, fatigue, and nausea. Hyperglycaemia requires correction using an insulin shot or via an insulin pump.
The goal of treatment for type 1 diabetes is to keep blood glucose levels as close to normal as possible, ie: daytime blood glucose levels before meals 3.9–7.2 mmol/L and no higher than 10 mmol/L two hours after meals. To achieve these goals, a combination of treatment approaches is required, including:
- Insulin therapy (insulin replacement)
- Frequent blood glucose monitoring
- Carbohydrate counting
- Eating healthy foods (low-fat high-fibre foods)
- Exercising regularly (at least 30 minutes on most days of the week)
- Maintaining a healthy bodyweight.
Type 1 diabetes requires lifelong insulin therapy, which is why the condition used to be known as insulin-dependent diabetes. Insulin can be given by injection or via a continuous insulin pump.
With insulin injections, a syringe with a fine needle or an insulin pen is used to inject insulin under the skin. Most people require two or more injections of insulin daily with different types of insulin and with doses adjusted based on self-monitoring of blood glucose levels.
There are two main types of insulin: basal insulin (continuous background insulin) and bolus insulin (an extra dose of insulin given before meals). Basal insulin is either long-acting (e.g. glargine) or intermediate-acting (e.g. isophane). Bolus insulin is either rapid-acting (e.g. lispro, aspart, or glulisine) or short-acting (e.g. neutral).
An insulin pump is a small device worn on the outside of the body. A tube connects a reservoir of insulin to a catheter that is inserted under the skin of the abdomen. The pump is programmed to dispense specific amounts of insulin. This would typically be a constant low dose of fast-acting insulin to act as the basal background insulin and the user giving a bolus dose of the fast-acting insulin to cover meals.
Blood glucose and ketone monitoring
Optimal diabetic control requires frequent self-monitoring of blood glucose levels as this allows for timely adjustments in insulin doses. People with type 1 diabetes should learn how to self-monitor their blood glucose levels using a pocket-sized blood glucose meter and adjust their insulin doses accordingly.
Depending on whether daily insulin injections or an insulin pump is used, blood glucose levels will likely need to be checked at least four times a day. Careful monitoring is the only way to ensure that blood glucose levels remain within the target range.
Blood glucose testing involves using a lancing device to prick the skin to draw a drop of blood, which is placed on a test strip. The test strip is then inserted into a blood glucose meter, which provides a blood glucose level reading.
Blood ketone meters, which measure blood ketone levels, and work in a similar way to blood glucose devices, are available to test for ketoacidosis.
Lifestyle and home remedies
Careful management of type 1 diabetes is important to reduce the risk of acute and long-term serious complications. The following tips will help:
- Wear a tag or bracelet that says you have diabetes, in case of emergency
- Get yearly physical check-ups and regular eye checks to look for diabetes-related complications
- Get annual influenza (and possibly pneumonia) vaccinations as high blood glucose levels can weaken the immune system
- Wash and moisturise your feet daily and check them for blisters, cuts, and sores
- Control blood pressure and cholesterol levels to help minimise the risk of complications
- Quit smoking. Smoking increases the risk of complications
- Drink alcohol responsibly. Alcohol can cause high or low blood glucose levels
- Minimise stress. Stress hormones may prevent insulin from working properly.
Further information and support
For further information and support contact your doctor, practice nurse, or:
Diabetes New Zealand
Postal address: PO Box 12441, Thorndon, Wellington
Freephone: 0800 DIABETES (0800 342 238)
Diabetes Youth New Zealand
Postal address: P.O. Box 56172, Dominion, Road Auckland
Campbell-Stokes, P.L. (2005). Prospective incidence study of diabetes mellitus in New Zealand children aged 0 to 14 years. Diabetologia. 2005 Apr;48(4):643-8.
Derraik J.G., et al. (2012). Increasing incidence and age at diagnosis among children with type 1 diabetes mellitus over a 20-year period in Auckland (New Zealand). PLoS One. 2012;7(2):e32640.
Khardori R. (2016). Medscape drugs and diseases: Type 1 diabetes mellitus. New York, NY: WebMD LLC. http://emedicine.medscape.com/article/117739-overview [Accessed: 19/10/16]
Lamb W.H. (2016) Medscape drugs and diseases: Pediatric type 1 diabetes mellitus. New York, NY: WebMD LLC. http://emedicine.medscape.com/article/919999-overview [Accessed: 19/10/16]
Mayo Clinic Staff (2016). Type 1 diabetes. Mayo Clinic: Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/type-2-diabetes/home/ovc-20169860 [Accessed: 19/10/16]
Mayo Clinic Staff (2015). Diabetic ketoacidosis. Mayo Clinic: Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/diabetic-ketoacidosis/basics/definition/con-20026470 [Accessed: 19/10/16]
O’Toole, M.T. (Ed.) (2013). Diabetes mellitus. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis: Elsevier Mosby.
Created: November 2016