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Diabetes mellitus, often called diabetes, is a condition that affects the body's ability to regulate the level of glucose in the blood. Glucose is the main form of sugar in the body.
What is going on in the body?
The pancreas, a long, thin organ located behind the stomach, makes insulin. Normally the pancreas makes extra insulin when a person eats. Insulin moves glucose from the bloodstream to the inside of body cells. This glucose, or sugar, is an important source of energy for the cells of the body. In a person with diabetes, the pancreas generally doesn't make enough insulin to move the glucose into the cells. In some types of diabetes, the body cells are resistant to the insulin. Glucose builds up in the blood, resulting in a condition known as hyperglycaemia.
There are 4 main types of diabetes mellitus:
What are the signs and symptoms of the disease?
- type 1 diabetes, also known as insulin dependent diabetes mellitus, Type 1 diabetes, or juvenile-onset diabetes mellitus. A person with this type of diabetes produces little or no insulin and needs regular insulin injections to survive.
- type 2 diabetes, also known as non-insulin dependent diabetes mellitus, Type 2 diabetes, or adult-onset diabetes. This is by far the most common type of diabetes. Someone with type 2 diabetes might produce normal or even high levels of insulin, but obesity makes his or her body resistant to its effect. Type 2 diabetes used to be rare in children, but now it is diagnosed in 20% of the children with diabetes. Of the children diagnosed with type 2 diabetes, 85% are obese.
- gestational diabetes or pregnancy-induced diabetes. This type of diabetes develops in a pregnant woman, and usually goes away after the birth of the child.
- the "other specific types" category of diabetes. This category includes diabetes caused by a genetic defect, pancreatic diseases, hormonal abnormalities, or exposure to certain drugs or chemicals.
Symptoms partly depend on the type of diabetes a person has and how long the diabetes has been untreated. Signs and symptoms are mostly related to high blood sugar levels, and include:
A condition called ketoacidosis may occur in an individual with type 1 diabetes if the person goes without enough insulin for too long. This is a severe complication and requires medical attention immediately. Symptoms include:
What are the causes and risks of the disease?
Genetics may play a part in all types of diabetes mellitus. Other causes and risks vary depending on the type of diabetes involved.
type 1 diabetes might be caused by autoimmune disorders, in which the body makes antibodies that destroy pancreatic cells. The rate of cell destruction is usually higher in children than in adults. Type 1 also has an idiopathic form, which has no known cause. Type 1 diabetes is more common in Caucasians than in other groups.
type 2 diabetes involves cell resistance to insulin. Glucose transport can be ineffective. Risk factors for type 2 diabetes include:
- obesity, which is the main cause of type 2 diabetes in both adults and children. A recent study showed a 33% increase in the number of Americans with type 2 DM over the past 8 years. The increase was 70% in people aged 30 to 39 years old and was attributed by researchers to a sharp rise in obesity in this population.
- race. Type 2 diabetes is more common in Indigenous Australians, Torres Straight Islanders and people of Asian decent.
- lack of physical exercise. A recent study showed that walking briskly for 3 hours a week, or exercising vigorously for an hour and a half each week, reduces a woman's risk of type 2 diabetes by 40%.
- high blood pressure, which is defined as a blood pressure equal to or greater than 140/90
- a low HDL ("good cholesterol") level, and/or an elevated triglyceride level
- an age of 45 or older
- a history of gestational diabetes, or delivery of babies whose birth weight is more than 4 kg
- possibly hormonal changes linked to menopause.
The "other specific types" category of diabetes includes:
- diabetes caused by hormonal imbalances. One example is Cushing's syndrome, which involves high levels of adrenal hormones.
- diabetes caused by medications, such as prednisone, thiazide diuretics, or oral contraceptives.
- diabetes caused by chronic inflammation, infection, or other damage to the pancreas.
What can be done to prevent the disease?
There is no way to prevent type 1 diabetes. The way to prevent Type 2 diabetes is to maintain a healthy body weight, eat a healthy diet, and exercise regularly. It is important to get 30 to 45 minutes of moderate physical exercise each day. Gestational diabetes can only be prevented by not getting pregnant.
A person can sometimes prevent diabetes mellitus by avoiding certain medications, such as oral contraceptives.
How is the disease diagnosed?
A doctor may suspect diabetes mellitus after taking a person's health history and doing a physical examination. Diabetes is diagnosed based on a high glucose level in the blood. There are several types of blood tests used to diagnose diabetes, including:
- a test for blood sugar known as the fasting plasma glucose test, which is the preferred method to diagnose most cases of diabetes. In this test, a person is asked to fast overnight, at least 8 hours, and the level of glucose in the blood is then checked. Normal fasting blood glucose levels are less than 6 mmol/L. A fasting blood glucose level of more than 8 mmol/L usually indicates diabetes
- a random test for blood sugar, or plasma glucose test, greater than 11mmol/L or higher indicates diabetes which can be done without fasting. A fasting glucose test or oral glucose tolerance test is done to confirm the diagnosis of diabetes.
- an oral glucose tolerance test which is the preferred way to diagnose gestational diabetes. In this test, a person is asked to drink a sweet liquid. Blood samples are then drawn at timed intervals. If a person does not have diabetes, the glucose levels will rise and then fall quickly after drinking the sweet liquid. When a person has diabetes, glucose levels will rise higher than normal and fail to come down as fast as those in a person without diabetes.
What are the long-term effects of the disease?
Over time, high blood sugar levels damage blood vessels, nerves, and other internal structures. Long-term effects of diabetes may include:
- retinopathy, a disease in the retina of the eye that can cause blindness. Diabetes is the number one cause of blindness in adults who are younger than 40 years of age.
- diabetic nephropathy, which is a disease of the kidneys. This disease can progress to a form of kidney failure known as chronic renal failure. Diabetes is the leading cause of chronic renal failure.
- arteriosclerosis, or hardening of the arteries. Arteriosclerosis contributes to heart attacksand strokes. It can also cause poor circulation in the legs and feet.
- diabetic neuropathy, or damage to nerves in the limbs. This damage can cause numbness and pain in the hands and feet. Neuropathy in combination with poor circulation can result in serious diabetic foot ulcers and leg infections that may require amputation.
- autonomic neuropathy, which may cause problems with digestion, diarrhoea, erectile dysfunction, a rapid heartbeat, and low blood pressure.
- skin infections, especially fungal infections such as ringworm, jock itch, and athlete's foot. Bacterial infections of the foot are common and can be life threatening.
- vaginal yeast infections, because high levels of sugar encourage the growth of yeast
- urinary tract infections
- coma or death, which may occur when a person's diabetes gets seriously out of control
What are the risks to others?
Diabetes is not contagious and poses no risk to others. It does tend to run in families.
What are the treatments for the disease?
Treatment depends on the type of diabetes that is present. A person with Type 1 diabetes generally needs insulin injections or Injections. The insulin Injections replace the insulin that is not produced by the pancreas. A proper diet is also important. Gestational diabetes is also usually treated with diet and insulin injections as needed.
The most effective treatment available for type 2 diabetes is weight loss. A proper diet for a person with diabetes and regular exercise for a person with diabetes are very important. A person with type 2 diabetes may also be treated with oral medications and/or insulin injections. The oral medications stimulate the pancreas to make more insulin or help the cells in the body use insulin and glucose more effectively.
Treating the underlying condition or stopping a certain medication may correct secondary diabetes caused by another medical condition. If this is not possible, diet, exercise, and pills or injections are used to control the blood sugar.
Careful monitoring and management help keep diabetes under control and reduce the risk of long-term effects. A person with diabetes is advised to:
Treating the complications of diabetes may involve many different specialists. For example, a person with diabetes may need to see eye, heart, foot, hormone, and circulation specialists. Dieticians also help people with diabetes by designing an eating plan. Dieticians can suggest appropriate kilojoule intake levels and types of foods to eat.
What are the side effects of the treatments?
Side effects depend on treatments used for diabetes. If a person has too much insulin in his or her body, the blood glucose levels can drop too low. This condition, called hypoglycaemia, can cause nervousness, shakiness, and confusion. The usual treatment for low blood sugar is to eat or drink a sweet beverage or food. If low blood sugar goes untreated, a person may become unconscious, or have seizures. Emergency medical attention is crucial in this situation.
The oral medications used for type 2 diabetes may cause weight gain, allergic reactions, or liver damage. Some may also cause low blood sugar levels.
What happens after treatment for the disease?
Diabetes generally cannot be cured, but it can be controlled with careful management and treatment. A person with diabetes will need lifelong monitoring to control blood sugar levels and prevent serious complications.
How is the disease monitored?
A person with diabetes should keep all of his or her appointments with the main doctor, as well as other scheduled specialists. Physical examinations, blood tests, urine tests, foot and skin care, routine eye examinations, and routine dental care are all part of basic care for a person with diabetes. The main goal of treatment is to keep blood sugar levels as close to normal as is safely possible. In general, ideal ranges of blood sugar levels are 4 to 6 mmol/L (millimoles per litre) before meals and 6 to 8 mmol/L at bedtime.
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request