What is diabetes?

Type 2 Diabetes Mellitus (T2DM)

Diabetes is a condition in which the body either finds it more difficult to produce a hormone called insulin or the body becomes more resistant to insulin (i.e. body doesn't react to it).

This results in high blood sugar levels (glucose) in the body which can lead to severe complications.

The video on the left from Diabetes UK provides a good introduction.


The beginning of T2DM


The pancreas (yellow organ shown in the picture) produces insulin which is a hormone ( a chemical that acts as a messenger within the body).

Insulin reduces blood sugar levels in the body when it is high.

Blood sugar is high after eating a meal and insulin comes into action to bring blood sugar levels back down to the normal range. The image below shows this.


T2DM develops over a period of 5-10 years prior to diagnosis.

This period of time is the pre-diabetic phase:

  1. During the time the body starts to lose the ability to respond to insulin.

  2. This causes the cells in the pancreas to work even harder to produce more to help lower blood sugar.

  3. Blood sugar levels slowly start to rise as the body becomes even more resistant to insulin.

  4. Eventually the cells in the pancreas become so overworked that amount of insulin produced decreases.

  5. Development of T2DM due to further increases in blood glucose levels and further health complications.

Understanding blood sugar readings


The key to understanding how well your T2DM is managed, is to know what level your blood sugar (glucose levels) should be.

There are three measurements to be aware of:

  1. Fasting blood glucose- this shows your blood sugar levels before eating on a daily basis.

  2. After eating (post-prandial) blood glucose- this shows your after eating a meal and should be taken 2 hours after the meal. This is shows blood sugar control on a daily basis.

  3. Glycosylated haemoglobin levels (HbA1C)- this is a blood test taken every 3-6 months and shows the long term control of blood glucose levels.


Specific targets and normal ranges are shown below

*HbA1c targets will be set by your GP


This shows how to interpret any readings you are given.

The higher the HbA1c level, the greater the risk of suffering from complications of diabetes.

Please see the section on complications for further details and what type 2 diabetes means for you.

Risk Factors


Type 2 diabetes has a number of risk factors. These build up over time, however, there are many which can be modified by implementing a healthy lifestyle.

  • According to NICE (The National Institute for Health and Care Excellence), obesity accounts for 80-85% of the overall risk for T2DM.

  • Risk is 2 - 4 times higher in the South-Asian, African and Afro-Caribbean ethnicities.

  • Having a family history of T2DM can increase the risk by 2 - 6 times.

  • Poor diet also has a major influence.

  • The older you get the greater the risk.

For information on maintaining a healthy lifestyle click here.