Diabetes Mellitus - Description, Causes, Symptoms, Treatment
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2.6 million people have been diagnosed with diabetes in the UK equivalent, on average, to 4 out of every 100 people. About 150,000 new cases of diabetes are diagnosed every year. By 2025, because of the ageing population and the rising levels of obesity, the number of people with diabetes in the UK is expected to grow to over 4 million.
There are two forms of diabetes, type 1 and type 2. About 10% of patients have type 1 diabetes, the remaining 90% have type 2 diabetes.
Type 1 diabetes is characterised by a total lack of insulin. It usually begins under the age of 40 and there is normally no history of the disease in the family.
Type 2 diabetes is mainly due to resistance or insensitivity to insulin, rather than to a total lack of insulin, but a relative deficiency of insulin can be seen in some people. Type 2 diabetes generally occurs after the age of 40 and there is a strong history of the disease in the family. It is common in Asian and Afro-Caribbean communities and tends to appear at a much earlier age, often after the age of 25. Type 2 diabetes is particularly associated with obesity and a lack of exercise. About 60-80% of patients with type 2 diabetes are obese. It is estimated that there may be up to half a million people in the UK with type 2 diabetes who do not realise that they have the disease.
Insulin has a number of effects, but one of its main effects is to stimulate the liver to take glucose from the circulation and to convert it into glycogen, which is stored in the liver for future use. Insulin also stimulates muscle cells to take up glucose from the circulation, and this glucose is used to provide energy to power the muscles.
Diabetes occurs when the levels of glucose circulating in the blood stream remain abnormally high. This can happen for two main reasons. In type 1 diabetes there is little or no insulin secreted by the beta cells of the pancreas. The reason for this is not absolutely clear but is thought to be due to the body's immune system attacking and destroying the beta cells. It is not known what triggers this immune response but is probably caused by a viral or bacterial infection.
In type 2 diabetes it appears that the tissues become resistant to the effects of insulin. The liver and muscle cells respond less well to the effects of the hormone and consequently are less able to remove glucose from the circulation. There may also be a decrease in the amount of insulin secreted by the pancreas.
Type 2 diabetes is strongly associated with being overweight; 60-80% of people with type 2 diabetes are obese. It is probable that the receptors on the liver and muscle cells that respond to insulin, and the beta cells of the pancreas that produce insulin, have become overloaded by the excess glucose they have to deal with and, consequently, no longer function properly.
Signs similar to diabetes may also appear during pregnancy, when it is called gestational diabetes, or as the result of drug treatment with thiazide diuretics or corticosteroids. The signs normally disappear after the baby is born or once drug therapy is withdrawn.
Whether someone has type 1 or type 2 diabetes, the symptoms are generally the same. They include an increased thirst, frequent trips to the toilet to urinate (especially at night), extreme tiredness, weight loss, genital itching, thrush (in women) and blurred vision. In type 1 diabetes, patients may also develop ketoacidosis, where the body breaks down fat instead of glucose. Patients develop a sweet 'pear-drop' smell on their breath. If the ketoacidosis is not treated the patient can pass into a coma and die.
In addition to the above symptoms, diabetes can lead to long-term health problems. The raised blood glucose levels damage blood vessels and nerves, dramatically increasing the risk of heart attacks, stroke, kidney failure, limb amputations and blindness. It is critical therefore that diagnosis of diabetes is made as early as possible and that blood glucose levels are kept under control.
Treatment of type 2 diabetes begins with the control of diet, losing weight and increasing exercise. In many cases, these changes in lifestyle will prevent the disease from developing.
If these lifestyle measures are not sufficient, there are a number of drug treatments that may be used. Drugs such as glimepiride, glipizide and glibenclamide, known collectively as sulphonylureas, stimulate the pancreas to produce more insulin. Another drug called metformin, used widely in the treatment of type 2 diabetes and sometimes also in type 1 diabetes, acts by reducing the breakdown of glycogen to glucose in the liver, by increasing the uptake of circulating glucose by muscles and by inhibiting the absorption of glucose.
If metformin or a sulphonylurea, used alone or with one another, fails to produce the desired control of glucose levels other classes of drugs may be used in combination with them to increase their effect. These other classes of drug include the PPAR? agonists, DPP-4 inhibitors and the GLP-1 agonists.
PPAR? agonists, also known as glitazones or thiazolidinediones, for example pioglitazone and rosiglitazone help overcome resistance to insulin at fat tissue, skeletal muscle and liver, thereby producing a further fall in the concentration of glucose in the blood. PPAR? agonists should not be used in people who have a history of heart problems because of risks of adverse effects. Because of these risks, the European Medicines Agency announced in September 2010 that rosiglitazone's licence will be suspended and the product will stop being available in Europe. Anyone currently taking rosiglitazone should make an appointment with their doctor to discuss suitable alternative treatments. Patients are advised not to stop their treatment without speaking to their doctor.
DPP-4 inhibitors, for example saxagliptin, sitagliptin, and vildagliptin, stimulate an increase in insulin secretion and a decrease in the level of another hormone called glucagon, helping to control blood glucose levels when fasting (ie between meals) and helping to reduce the rise in glucose levels after meals.
GLP-1 agonists, (glucagon-like peptide-1), for example exenatide and liraglutide both increase insulin secretion, decrease glucagon secretion, and slow the rate at which the stomach empties, thereby delaying digestion and absorption of glucose. Treatment with exenatide and liraglutide is associated with the prevention of weight gain which can be beneficial in people with type 2 diabetes who are overweight.
People with type 2 diabetes may eventually need insulin too.
Doctors will often use a combination of these different types of drugs to ensure that glucose levels are controlled.
When to see your pharmacist
If you are using insulin, your pharmacist will be able to advise you about storing it correctly, what to do when you go on holiday and will suggest items such as pre-filled insulin pens that make selecting dosages and administration easier.
If you are taking tablets to control your diabetes, your pharmacist will let you know whether it is safe to take other medicines, in particular over the counter medicines and health supplements, that you may be using to treat other illnesses.
Lancets used to prick your finger and test strips to test blood glucose levels are available on prescription, but the finger pricking devices and blood glucose meters are not. Your pharmacist will be able to let you know which equipment goes together and from where it may be obtained.
Talk to you pharmacist if you also want practical advice on life style changes such as stopping smoking, lowering cholesterol levels and changing your diet.
When to see your doctor
Living with diabetes
Keep a close eye on your blood glucose levels to make sure that they stay within normal limits. If levels remain too high there is a risk of long term damage to blood vessels and nerves. If glucose levels go too low as a result of excess drug treatment or missing meals there is a risk of hypoglycaemia or 'hypos'.
Scientific research has shown that people who regularly monitor their blood glucose levels feel better, are less depressed, have fewer heart problems, less complications and a lower risk of death than those who do not monitor regularly. Consequently, get into the habit of monitoring your blood glucose levels regularly, and strive to keep the levels within the target figures set for you by your doctor or diabetes care team. It is important to do this even when feeling well since the effects of uncontrolled blood glucose levels may not become obvious for many years, by which time irreversible damage may have occurred.
Experts recommend that people with diabetes test before and after meals to gain the greatest benefit from their blood glucose monitoring. The best times to test are just before and 2 hours after the largest meal of the day. It is important to test before breakfast, when you have not eaten for several hours, and can record fasting blood glucose levels. If you use insulin, you should test at least three times every day. If you do not use insulin you can test less frequently. It is more useful to test several times during 1 or 2 days a week rather then once every day.
You should test more often if you are pregnant, elderly, stressed or unwell, planning to drive, exercise or operate machinery, and when stopping, starting or changing any new medication. Knowing your blood glucose pattern through frequent monitoring allows you to get on with your normal activities safely and without worry.
If you are unsure how to test your blood glucose levels, or are have difficulty in using a blood glucose meter talk to your pharmacist, doctor or nurse for help and advice. There are many meters on the market; it is just a case of finding one that suits you best.
Similarly, if you have problems with your vision talk to your pharmacist, doctor or nurse as there are many products that are specially adapted to help
- Have regular check-ups
- Change your eating habits, keep an eye on sugar and starch intake. Discuss suitable diet plans with your nurse, doctor or dietician
- Give up smoking - smoking increases the chance of developing long-term health problems
- Keep fit - take up regular physical activity such as walking, swimming or dancing.
- Remember to test blood glucose levels regularly
Diabetes UK Central Office
10 Parkway, London NW1 7AA
Tel 020 7424 1000
Careline: 0845 120 2960 (Monday-Friday, 9am-5pm)
Or if you are in Scotland: firstname.lastname@example.org.
Reviewed on 23 September 2010