diabetes and its control Flashcards
types of diabetes
If you suffer from diabetes your pancreas either does not produce enough insulin, or your body cannot effectively respond to the insulin produced. This means that blood glucose concentration remains high. Hyperglycaemia, or raised blood sugar, is a common effect of uncontrolled diabetes. Over time this can lead to serious damage of many body systems, especially the nerves and blood vessels.
There are two main types of diabetes:
• Type 1 diabetes. Patients with type 1 diabetes are unable to produce insulin. The B cells in the islets of Langerhans do not produce insulin. The cause of type 1 diabetes is not known and so, at the moment, the disease cannot be prevented or cured. It is possible, however, to treat the symptoms. Evidence suggests that in many cases the condition arises as a result of an autoimmune response where the body’s own immune system attacks the B cells.
This condition normally begins in childhood, and people develop symptoms of the disease quickly.
•
Type 2 diabetes. Patients with type 2 diabetes cannot effectively use insulin and control their blood sugar levels. This is either because the person’s B cells do not produce enough insulin or the person’s body cells do not respond properly to insulin.
This is often because the glycoprotein insulin receptor on the cell membrane does not work properly. The cells lose their responsiveness to insulin, and therefore do not take up enough glucose, leaving it in the bloodstream. Globally, approximately 90% of people with diabetes have type 2 diabetes. This is largely as a result of excess body weight, physical inactivity, and habitual, excessive overeating of (refined) carbohydrates.
Symptoms are similar to those of type 1 diabetes, but are often less severe and develop slowly. As a result, the disease is often only diagnosed after complications have already arisen. Risk of type 2 diabetes increases with age. Until recently, this type of diabetes was seen only in adults (normally over the age of 40), but it is now also occurring in children.
symptoms of diabetes
• High blood glucose concentration
• Glucose present in urine
• Excessive need to urinate (polyuria)
• Excessive thirst (polydipsia)
• Constant hunger
• Weight loss
• Blurred vision
• Tiredness
symptoms of diabetes
• High blood glucose concentration
• Glucose present in urine
• Excessive need to urinate (polyuria)
• Excessive thirst (polydipsia)
• Constant hunger
• Weight loss
• Blurred vision
• Tiredness
type 1 diabetes treatment
Type 1 diabetes is controlled by regular injections of insulin and is therefore said to be insulin-dependent.
People with the condition have to regularly test their blood glucose concentration, normally by pricking their finger. The drop of blood is then analysed by a machine, which tells the person their blood glucose concentration. Based on this concentration, the person can work out the dose of insulin they need to inject. The insulin administered increases the amount of glucose absorbed by cells and causes glycogenesis to occur, resulting in a reduction of blood glucose concentration.
If a person with diabetes injects himself or herself with too much insulin, they may experience hypoglycaemia (very low blood glucose concentrations) that can result in unconsciousness. However, too low an insulin dose results in hyperglycaemia, which can also result in unconsciousness and death if left untreated. Careful monitoring and dose regulation is therefore required.
Figure 3 shows how blood glucose concentration and insulin levels vary in a person with type 1 diabetes, and a person without diabetes.
If the person with diabetes injects himself or herself with insulin, there will be a surge of insulin in their blood which will cause their blood glucose level to drop quickly.
type 2 diabetes treatment
The first line of control in type 2 diabetes is to regulate the person’s carbohydrate intake through their diet and matching this to their exercise levels. This often involves increasing exercise levels.
Overweight people are also encouraged to lose weight. In some cases, diet and exercise are not enough to control blood glucose concentration so drugs also have to be used. These can include drugs that stimulate insulin production, drugs that slow down the rate at which the body absorbs glucose from the intestine, and ultimately even insulin injections.
medically produced insulin
Originally, insulin was obtained from the pancreas of cows and pigs which had been slaughtered for food. This process was difficult and expensive. The insulin extracted could also cause allergic reactions as it differed slightly from human insulin.
In 1955, the structure of human insulin was identified and it is now made by genetically modified bacteria. This has a number of advantages:
• Human insulin is produced in a pure form
- this means it is less likely to cause allergic reactions.
• Insulin can be produced in much higher quantities.
-Production costs are much cheaper.
-People’s concerns over using animal products in humans, which may be religious or ethical, are overcome.
potential use of stem cells in diabetes treatment
For decades, diabetes researchers have been searching for ways to replace the faulty B cells in the pancreatic islets of diabetic sufferers.
Each year, over 1000 people with type 1 diabetes receive a pancreas transplant. After a year, over 80% of these patients have no symptoms of diabetes and do not have to take insulin. However, the demand for transplantable pancreases far outweighs their availability. The risk of having a transplant can also be a greater health risk than the diabetes itself - immunosuppressant drugs are required to ensure the body accepts the transplanted pancreas, which can leave a person susceptible to infection.
Doctors have attempted to cure diabetes by injecting patients with pancreatic ß islet cells, but fewer than 8% of cell transplants performed have been successful. The immunosuppressant drugs used to prevent rejection of these cells increases the metabolic demand on insulin-producing cells. Eventually this exhausts their capacity to produce insulin.
As type 1 diabetes results from the loss of a single cell type, and there is evidence that a relatively small number of islet cells can restore insulin production, the disease is a perfect candidate for stem cell therapy. Totipotent stem cells have the potential to grow into any of the body’s cell types. Scientists have been researching the best type of stem cells and the signals required to promote their differentiation into B cells, either directly in the patient or in the laboratory before being transplanted. It is likely that the stem cells used in diabetes treatment would be taken from embryos. To obtain the stem cells, the early embryo has to be destroyed. This means destroying a potential human life. However, the embryos used as a source for these stem cells would usually be destroyed anyway - they are ‘spare’ embryos from infertility treatments or from terminated pregnancies.
Stem cells lines formed from a small number of embryos can be used to treat many patients - each treatment does not require a separate embryo. An alternative to using embryonic matter is that of using preserved umbilical stem cells.
Stem cells offer many advantages over current therapies:
• donor availability would not be an issue - stem cells could produce an unlimited source of new B cells
• reduced likelihood of rejection problems as embryonic stem cells are generally not rejected by the body (although some evidence contradicts this). Stem cells can also be made by somatic cell nuclear transfer (SCNT)
• people no longer have to inject themselves with insulin.
However, because our ability to control growth and differentiation in stem cells is still limited, a major consideration is whether any precursor or stem-like cells transplanted into the body might induce the formation of tumours as a result of unlimited cell growth.
