What is diabetes?

Here, you can find out exactly what happens when you develop diabetes, and what you can do to help your body stay as healthy as possible.

The full name for diabetes is ‘diabetes mellitus’. The word ‘diabetes’ means excessive urination and ‘mellitus’ means honey. The name comes from the way doctors used to diagnose diabetes in previous centuries. They would taste the patient’s urine and if it tasted sweet they were said to have diabetes.

Having diabetes means that your body produces too little or no insulin. If you have type 2 diabetes (also known as non-insulin dependent diabetes), your body produces some insulin, but less than you need. The insulin you do produce does not work properly. Diabetes is a life-long condition.

What goes wrong in diabetes?

Insulin is a hormone that plays a very important role in your body. Insulin acts like a key to open the doors into your cells, letting sugar (glucose) in.

When you have diabetes, your pancreas makes too little insulin to allow all the sugar in your blood to get into your body’s cells. These use sugar as fuel.

If sugar can't get into the cells, it builds up in the bloodstream. This makes the concentration of glucose in your blood (blood glucose or blood sugar) too high.

If diabetes is untreated, you have high blood sugar levels. You also pass high quantities of sugar in the urine. That explains the practice, in the old days, of tasting the urine to diagnose diabetes.

What causes type 2 diabetes?

Type 2 diabetes develops when the insulin-making cells in the pancreas start to become inefficient. They begin to produce too little insulin for the body’s needs. This is most noticeable after eating.

Type 2 diabetes may also develop when the cells in the body become less responsive to insulin. When this happens, even though you may still be making some insulin, it cannot do its job properly.

Who is at risk of getting type 2 diabetes?

The causes of type 2 diabetes may differ from one person to another.

In most cases, the cause is unclear, but a few cases can be attributed to specific genetic defects. Indeed, most cases are likely to have some genetic basis, as type 2 diabetes tends to run in families.


Type 2 diabetes is diagnosed more often in certain ethnic groups.

Lifestyle is also important in determining whether or not someone with a tendency to type 2 diabetes will actually develop the disease. Type 2 diabetes is more common in people who take too little exercise, eat a high-fat or high-calorie diet and/or are overweight.

Women who develop diabetes during pregnancy (gestational diabetes) are more prone to the disease in later life.

Before you developed diabetes

When your pancreas was working normally and produced the necessary insulin, your body automatically kept your blood sugar exactly at the right level throughout the day and night.

The amount of sugar in the blood must not get too high or too low. Two hormones - insulin and glucagon - are produced in the pancreas to ensure blood sugar levels are well controlled through the day.

Blood sugar and food

Blood sugar rises after eating. Before you had diabetes, insulin would be released into your blood after each meal you ate, to remove the sugar from your blood stream and transport it to different cells in your body.

Insulin acts like a key. It opens doors in the muscle cell walls, enabling sugar from your blood to get into the cell to provide energy. By removing sugar from the blood and taking it to body cells, insulin also lowers blood sugar to its normal level again. When this mechanism works properly, blood sugar levels stay low, usually lower than 6.0 mmol/l in the morning.

Diagnosing type 2 diabetes

There are guidelines available to help doctors diagnose diabetes. According to these guidelines, people without diabetes have fasting blood glucose no higher than 6.0 mmol/l.

If fasting blood glucose is 7.0 mmol/l or above, and/or it rises to more than 11.1 mmol/l two hours after oral glucose load, you are diagnosed as having diabetes.

People who have blood glucose levels between normal and diabetic values two hours after oral glucoase load are said to have “impaired glucose tolerance”. This is a condition which increases the likelihood of developing diabetes in the future.

When you have type 2 diabetes

When you have diabetes, you are not producing enough insulin ‘keys’ to open the doors into your body’s cells. The effects of this start to show in how you feel and how your body acts. So when sugar can't get into your muscle and other cells to produce energy, you feel tired. Also, as the sugar cannot get into the cells to be used, it builds up in the bloodstream.

Sugar in the urine

Without enough insulin, the amount of sugar in your bloodstream rises to very high levels. When that happens, some of the sugar finds its way through the kidneys into your urine. The sugar that spills into the urine carries a lot of water along with it, which makes you very thirsty, so you find yourself drinking a lot and needing to urinate frequently.


Treating type 2 diabetes

Once you’ve been diagnosed, you will need to keep your blood sugar under control. This will help you feel good, lead a normal life and avoid the long-term complications of diabetes.

The risk of developing future complications increases if your pre-meal blood sugar is above 6.0 mmol/l, and/or if your blood sugar 1.5-2 hours after a meal is above 7.5 mmol/l. You can set targets for your blood sugar with your doctor.
To keep your blood sugar under control, now that you have diabetes, you have to do what your body once did automatically.

You may be able to make better use of the insulin that your body still produces by:

  • Improving your diet
  • Taking regular exercise
  • Losing weight, if you need to.
If these measures don’t work, you can take medication that increases your body’s insulin production or your body’s sensitivity to insulin.

After some time, this kind of treatment may not work well enough. If this happens, you may need to start having insulin injections. You may also need to do this if your body is under stress, for example if you are ill.

The diabetes care team

There’s a whole team of specialists who will help you look after your diabetes. These are likely to include:

  • Your diabetes specialist doctor
  • Your diabetes nurse
  • Your GP
  • Your practice nurse
  • A dietician
  • A chiropodist/podiatrist


    • Make full use of these experts. They can help you manage your diabetes with plenty of good advice and support.

    Other support services

    Most clinics will be able to give you information leaflets to take away and read in your own time.

    There may also be a support group in your neighbourhood, where you can meet others with diabetes and share your experiences and advice. Contact the national organisation Diabetes UK for more details.

    Diabetes education packages are now available for computer users, and your doctor can tell you about these too.

    What is diabetes? A summary

    • It is caused by the body making too little or no insulin
    • It can also involve a reduced sensitivity to the effect of insulin
    • It is a condition that’s for life
    • Insulin allows sugar to be transported to the body’s cells
    • Lack of insulin leads to build-up of sugar in the blood
    • Untreated diabetes can make you feel tired, thirsty and urinate more frequently
    • Treatment for diabetes can be:
      - Diet and exercise
      - Medication to increase insulin production or insulin sensitivity
      - Insulin injections
    • Keeping blood sugar levels low helps prevent long term health complications

     

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    Last updated: May 2007