Reproduced with consent from the Diabetes Research Centre at the Walter + Eliza Hall Institute of Medical Research and the Royal Melbourne Hospital (www.diabetestrials.org)
WHAT IS DIABETES?
Diabetes is a life-long condition that can affect both children and adults. It occurs when the hormone, insulin, is not present, or is unable to do its job properly. The body needs insulin to transport glucose, the body’s fuel, to where it is needed. Without insulin, glucose stays in the blood, instead of going to the organs. This 'high blood sugar' is how we diagnose diabetes.
TYPES OF DIABETES
Type 1 Diabetes
What is type 1 diabetes?
Type 1 diabetes is one of the most common chronic diseases beginning in childhood and is becoming more common, with 100,000 Australians now depending on insulin injections every day.
Type 1 diabetes is due to a lack of the hormone, insulin, which is produced by cells in the pancreas called beta cells. Without insulin, the body can’t use glucose, an important source of energy. The level of glucose in the blood then increases; causing symptoms such as thirst, frequent urination, dehydration weight loss and sometimes coma. When insulin is given regularly by injection or pump therapy, the blood glucose levels can be controlled but are never perfectly normal.
This sets the stage for longer-term complications involving blood vessels and nerves, which may lead to cardiovascular disease, blindness, kidney failure and other problems.
How does type 1 diabetes occur?
The insulin-producing beta cells are destroyed in type 1 diabetes because the body’s immune system starts attacking them as if they are foreign. People who develop type 1 diabetes have a genetic susceptibility, but factors in the environment such as infections are also necessary to trigger the misdirected immune response against the beta cells.
Until the 1970s, very little was known about how type 1 diabetes occurred. Medical researchers have discovered most of what is known in just the last three decades. Some of these discoveries have occurred in Australia. In the 1970s, researchers in Sydney discovered that women who contracted German measles (rubella) during pregnancy gave birth to children with a high risk of getting type 1 diabetes. Vaccination against rubella has put a stop to this, but there are obviously other important environmental factors because the incidence of the disease is not decreasing.
Recently, researchers in at the Walter and Eliza Hall Institute and Royal Melbourne Hospital discovered an important link with another virus called rotavirus. Rotavirus infection, the commonest cause of diarrhoea in infants, was found to be associated with the onset of the immune attack against the beta cells. The same researchers in Melbourne have identified genes that predispose to type 1 diabetes, identified chemicals from immune cells that kill the beta cells, developed tests that identify children likely to get type 1 diabetes and are now ready to conduct trials to prevent type 1 diabetes.
Melbourne researchers are in a leading position to take up the challenge to prevent type 1 diabetes. The benefits to children and families would be inestimable.
Can type 1 diabetes be prevented?
By understanding how the immune system kills the beta cells that make insulin, Melbourne researchers have been able to demonstrate the prevention of diabetes in specific conditions. This milestone has lead to a vaccine that has recently undergone a successful pilot trial in children and adolescents who were at high risk for the disease. A large trial of this vaccine in many centres in Australia is now planned to determine if the vaccine will stop children at risk from becoming diabetic.
The researchers first need first to identify those at risk and estimate their chances of getting diabetes within a specified time. This is done by a simple blood test. However, for every 100 screened no more than three are likely to be eligible for the prevention trial. Many thousands of children and adolescents will have to be screened therefore to identify those at risk and eligible for the trial. This massive logistical exercise requires funding that falls outside the scope of available research funding.
Type 2 Diabetes
Type 2 diabetes is much more common than type 1 diabetes, affecting about 10% of Australian adults. Its frequency is increasing dramatically throughout the country.
Whilst people with type 1 diabetes have insufficient insulin production (insulin is unavailable), those with type 2 diabetes have faulty insulin action (insulin is present, but the body has trouble using it). This so-called ‘insulin resistance’ develops very slowly. As a result, at the time of diagnosis, individuals with type 2 diabetes may have had the disease for several years, and often do not feel particularly unwell. However, over a period of many years, type 2 diabetes can cause significant health problems.
Like type 1 diabetes, type 2 diabetes can damage the eyes, kidneys and feet, especially if blood glucose is not controlled. Type 2 diabetes also carries a much greater risk of heart disease and stroke. These risks can be reduced by treatment of high cholesterol and high blood pressure in addition to glucose control.
Although most people with type 2 diabetes do not require insulin injections at the time of diagnosis, after several years of type 2 diabetes, the body may lose the ability to make insulin so that insulin injections are required.
The high prevalence of type 2 diabetes and the high personal and financial costs of its treatment and complications make this disease a national health priority. Prevention strategies that increase opportunities for exercise and healthy eating are being implemented in several communities and should help reduce the number of people developing type 2 diabetes. There is also intense research into the causes of insulin resistance in the expectation that this will lead to improved treatments for type 2 diabetes.
LADA
What is Latent Autoimmune Diabetes in Adults?
LADA is a when both type 1 and type 2 diabetes occurs in one individual.
Diabetes or a high blood sugar results from a lack of insulin production or a lack of insulin action in the body’s tissues. It is well known that type 1 diabetes is a condition in which the immune system reacts against the insulin-producing beta cells in the pancreas, a process known as autoimmune destruction. Autoimmune destruction of the beta cells eventually results in a lack of insulin. Type 2 diabetes is a different process whereby initially insulin production in the beta cells is sufficient but the insulin does not work as well at distant sites in the body due to insulin resistance. In some cases it is not clear which type it is, and that a combination of both processes can lead to diabetes.
In the last ten years it has become evident from research that there are many people who have both type 1 and 2 diabetes processes. The largest study to show this was the United Kingdom Prospective Diabetes Study published in 1997. They identified that one in 10 adults (age 25 – 65) with presumed type 2 diabetes had evidence of a type 1 diabetes autoimmune process as well. This result has been replicated in many other research studies as well. This condition is also known as latent autoimmune diabetes in adults (LADA). These people are different from children with type 1 diabetes because they clinically present as someone with type 2 diabetes, they do not require insulin for at least 6 to 12 months after diagnosis of their diabetes and may be overweight.
Gestational Diabetes
Gestational diabetes, as its name suggests, is a form of diabetes that develops during pregnancy. It usually appears in the last trimester of pregnancy, and disappears shortly after birth, although it can frequently recur in later pregnancies, and may indicate an increased risk of diabetes later in life.
Like type 2 diabetes, gestational diabetes is characterised by insulin resistance – that is, your body is creating enough insulin to keep you healthy, and it is doing its job of transporting glucose around your body, but cells are not responding to the insulin signal. In gestational diabetes, insulin resistance is the result of a rise in the level of pregnancy-related hormones which make sure the fetus gets enough glucose to continue growing and developing appropriately. It does this by making the mother’s cells more resistant to insulin so more glucose gets to the fetus.
The mother’s body compensates for this by creating more insulin, and by using stores of fat to create energy for her own consumption. In about 5% of pregnancies, however, the mother’s body can’t create enough insulin to keep up with the rising hormone levels, and gestational diabetes is the result.
Gestational diabetes is usually treated quite aggressively, with diet and exercise plans, but also frequently with insulin injections. Specialist obstetric endocrinologists, diabetes educators and nutritionists will work with expectant mothers to keep blood sugar as close to normal as possible. This is because gestational diabetes poses health risks to both mother and baby, which can be greatly reduced with good prenatal care.
CONCLUSION
A diagnosis of diabetes in any individual signifies a dramatic upheaval in the life of that person and their family. Major adjustments and changes to lifestyle are almost always necessary to accommodate careful monitoring of glucose levels, dietary adjustments, and in many cases insulin delivery by injection up to four times a day. Failure to do this can be life threatening. In addition, skin prick tests, to measure the level of sugar (glucose) in the blood, must be done repeatedly in a day to work out how much insulin is needed in each dose.
Without a doubt, diabetes places an enormous burden on the individual diagnosed as well as their family, day after day with no chance of a cure.