Causes, symptoms and diagnosis

Long term conditions: Diabetes blood sugar test

There are many factors that can contribute to type 2 diabetes. You should ask your GP for a test for diabetes, if you:

  • are white and over 40 years old
  • are black, Asian or from a minority ethnic group and over 25 years old
  • and have one or more of the following risk factors:

Risk factors

  • A close member of your family has type 2 diabetes (parent or brother or sister)
  • You're overweight or if your waist is 31.5 inches or over for women, 35 inches or over for Asian men and 37 inches or over for white and black men
  • You have high blood pressure or you've had a heart attack or a stroke
  • You're a woman with polycystic ovary syndrome and you are overweight
  • You've been told you have impaired glucose tolerance or impaired fasting glycaemia
  • If you're a woman and you've had gestational diabetes
  • You have severe mental health problems.

The more risk factors that apply to you, the greater your risk of having diabetes.

Many people believe that too much sugar in your diet can cause diabetes, but there is no proof to support this theory. However, people who are overweight are significantly more at risk of developing type 2 diabetes, compared to people of a healthy weight.


Symptoms occur because some or all of the glucose stays in the blood and it isn't being used as fuel for energy. The body tries to reduce blood glucose levels by flushing the excess glucose out of the body in the urine. 

The main symptoms of undiagnosed diabetes can include:

  • passing urine more often than usual, especially at night
  • increased thirst
  • extreme tiredness
  • unexplained weight loss
  • genital itching or regular episodes of thrush
  • slow healing of cuts and wounds
  • blurred vision.

In type 1 diabetes the signs and symptoms are usually very obvious and develop very quickly, typically over a few weeks. The symptoms are quickly relieved once the diabetes is treated and under control.

In type 2 diabetes the signs and symptoms may not be so obvious, as the condition develops slowly over a period of years and may only be picked up in a routine medical check up. Symptoms are quickly relieved once diabetes is treated and under control.

If you have any of the above symptoms contact your GP. Early diagnosis, treatment and good control of diabetes is vital to reduce the chances of developing complications.


If your GP suspects diabetes, they will ask you for a blood sample to test. If your blood glucose levels are not high enough for your GP to diagnose diabetes, you may need to have a glucose tolerance test (also known as an oral glucose tolerance test).

This means you will be given a glucose drink and then your blood will be tested every half an hour, for two hours, to see how your body is dealing with the glucose.