Diabetes is a disease in which the body does not produce or properly use insulin, a hormone that is required to regulate blood sugar, needed for daily life.
Control of blood sugar level
Glucose, a simple form of sugar, enters the blood from the intestines, where is absorbed from food and sugary drink as a natural part of digestion. It is also produced by the liver, which acts as a store of energy.

One of the many functions of the blood is to carry glucose around the body. When it reaches the various body tissues, such as the muscle cells, it is converted into energy. The precise concentration of glucose in the blood is automatically regulated. Crucial to this is the hormone insulin, which is secreted into the blood by the pancreas – a gland found behind and below the stomach.

Insulin is required for the conversion of glucose into energy. With the digestive system and liver working normally, a shortage of insulin causes glucose to build up in the blood, leading to the symptoms of diabetes. Poorly controlled blood sugar can also be a major threat to health, including increased risk of heart disease and strokes, nerve damage and blindness.
Types of diabetes
Type 1 diabetes
  • It is known as insulin dependent diabetes.
  • Occurs in people under 40
  • The person affected does not produce any of their own insulin and need to take it by injection every day. Once developed it is a life-long disease.
Type 2 diabetes
  • It is the most common type of diabetes.
  • Develops in adults over age 40
  • People with type 2 diabetes usually produce some insulin, but the body cells cannot use it efficiently because the cells are resistant to the insulin.
Diabetes in pregnancy
  • Develops during pregnancy in women who haven't previously had the condition
Causes of diabetes
Type 1 diabetes
  • Type 1 diabetes is caused by the destruction of insulin-producing cells called the islets of Langerhans within the pancreas – a gland found behind and just below the stomach.
  • The destruction of these cells is generally agreed to be caused by the body's own immune system. Consequently, diabetes is known as an autoimmune disorder.
Type 2 diabetes
  • It happens when the body's tissues don't respond well to insulin and so can't make use of the glucose in the blood for energy. The pancreas responds by producing more insulin and the liver, where glucose is stored, releases more glucose.
  • Eventually the pancreas becomes less able to produce enough insulin and the tissues become more resistant to insulin. As a result, blood glucose levels slowly start to rise.
  • It can take several years for blood glucose to reach a level that causes symptoms of type 2 diabetes.
Diabetes in pregnancy
  • During pregnancy, various hormones block the usual action of insulin. This helps to make sure your growing baby gets enough sugar. Your body needs to produce more insulin to cope with these changes.
  • Gestational diabetes develops when your body can't meet the extra insulin demands of the pregnancy.
Symptoms of diabetes
Type 1 diabetes
  • Increased production of urine (because the body tries to get rid of the excess glucose in the urine, diluting with water)
  • Unusual thirst
  • Fatigue (because the glucose is not being converted into energy)
  • Loss of weight
  • Increased appetite
  • Feeling sick
  • Blurred vision
  • Infections such as thrush or irritation of the genitals
If type 1 diabetes is not treated at this stage, the body begins to produce chemicals called ketones to build up in the blood. This condition – diabetic ketoacidosis – causes additional symptoms:
  • Vomiting
  • Stomach pain
  • Rapid breathing
  • Increased pulse rate
  • Sleepiness
Without treatment, diabetic ketoacidosis can lead to coma or death.

Type 2 diabetes
Many people with type 2 diabetes have no symptoms, and it's often discovered accidentally after routine medical check-ups or following screening tests for other conditions.

If you do have symptoms of type 2 diabetes, they might include:
  • excessive passing of urine
  • constant thirst
  • tiredness
  • blurred vision
  • itchy skin around your genitals or regular infections, such as thrush
You may also have noticed a change in your weight over recent months. You may have gained some (causing diabetes) or lost some as a result of high blood glucose levels. It's also possible that your weight hasn't changed at all because of a combination of high blood glucose and a high calorie diet.

Diabetes in pregnancy
Gestational diabetes doesn't usually cause any symptoms. Sometimes you may have symptoms of high blood sugar, including:
  • increased thirst
  • needing to urinate often
  • feeling tired
Diagnosis of diabetes
Type 1 diabetes
  • Type 1 diabetes can be picked up with a blood test to measure the level of glucose in the blood. It may be necessary to fast for eight hours before the blood sample is taken.
Type 2 diabetes
  • You may be asked to have a blood test to measure the level of glucose in your blood. This might be a fasting glucose test, which is taken after you haven't eaten for at least eight hours, or a glycosylated hemoglobin (HbA1c) test done at any time.
  • If your doctor can't make a definite diagnosis after these tests, you may have a glucose tolerance test. This measures how your blood glucose level changes over time after you swallow a sugary drink. You will need to fast overnight before having this test.
Diabetes in pregnancy
  • Gestational diabetes can be diagnosed using a glucose tolerance test, which is carried out in the morning, after you have eaten nothing overnight. Your doctor will give you a solution of glucose to drink and take blood samples at different intervals to see how your body deals with the glucose over time.
  • If you're at risk of developing diabetes in pregnancy, you will be offered a glucose tolerance test by your doctor or midwife between 24 and 28 weeks. If you have had gestational diabetes before, you will be offered a test at 18 weeks, and another one at between 24 and 28 weeks if the first is normal.
Treatment of diabetes
Type 1 diabetes
  • Type 1 diabetes cannot be cured, but it can be controlled by insulin injections. Insulin cannot be taken in tablet form because it is destroyed by the acids in the stomach. Insulin injections are usually self-administered to the skin of the abdomen two or four times a day, using either a traditional hypodermic needle or a pen type syringe with refillable cartridges. There are different kinds of insulin that work at different rates and for different lengths of time.
Type 2 diabetes
  • Some people with type 2 diabetes can initially control their condition with lifestyle changes alone.
  • If lifestyle changes alone don't reduce your glucose levels, you may be prescribed medicines to increase insulin production and strengthen its effect.
  • It's also possible that you will be given medicines to control your blood pressure if lifestyle changes including those mentioned above aren't enough to do this. Your doctor will prescribe either an angiotensin converting enzyme (ACE) inhibitor, or an angiotensin II receptor blocker depending on which is most suitable for you.
Diabetes in pregnancy
  • It's important that you control your blood sugar level. Most women can control it through a carefully planned diet and regular exercise.
  • Your meal plan will probably consist of these slow absorbing carbohydrates and a variety of lean proteins such as oily fishy, as well as at least five portions of fruit and vegetables each day.
  • Regular moderate intensity exercise, such as walking or cycling, helps to reduce blood sugar levels and promote a sense of wellbeing.
  • If the gestational diabetes cannot be controlled with diet and exercise and you will need insulin injections or tablets.
This information was published by Bupa Group's Health Content Team and has been reviewed by appropriate medical or clinical professionals. To the best of their knowledge the information is current and based on reputable sources of medical evidence, however Bupa (Asia) Limited makes no representation or warranty as to the completeness or accuracy of the Content.

The information on this page, and any information on third party websites referred to on this page, is provided as a guide only. It should not be relied upon as a substitute for professional medical advice, nor is it intended to be used for medical diagnosis or treatment. Bupa (Asia) Limited is not liable for any loss or damage you suffer arising out of the use of, or reliance on, the information.

Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. Last updated August 2017.
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