Blood tests

Blood glucose

If you have any symptoms of diabetes, or you have a higher risk of diabetes, for example, because you have a family history of the condition, your doctor may do a bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. test to check the levels of glucoseA simple sugar that is an important source of energy in the body. in your bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid..[1]

Blood glucoseA simple sugar that is an important source of energy in the body. levels can be checked after a period of fasting ('fasting bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body.') or without a period of fasting ('random bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body.'). The fasting bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. test is more accurate.

The World Health Organization criteria for diagnosing diabetes from a bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. test are as follows:[2]

  • A fasting glucoseA simple sugar that is an important source of energy in the body. of 7mmol/l (126mg/dl) or more indicates diabetes
  • A fasting glucoseA simple sugar that is an important source of energy in the body. of 6-7mmol/l (108-126mg/dl) suggests impaired glucose toleranceA level of insulin resistance that leads to high glucose levels, but not high enough for a diagnosis of diabetes. rather than full-blown diabetes
  • When a person does not have any symptoms, the diagnosisThe process of determining which condition a patient may have. of diabetes should be made only if at least two bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. tests have been done.

A random bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. result of 11.1 mmol/lMillimoles per litre - units of the amount of substance present. (200mg/dl) or more may also indicate diabetes.[3]

People with impaired glucose toleranceA level of insulin resistance that leads to high glucose levels, but not high enough for a diagnosis of diabetes. have bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels that are high, but not high enough for a diagnosisThe process of determining which condition a patient may have. of diabetes. These people have an increased risk of developing diabetes at a later stage, and also have a higher risk of cardiovascular disease.[3]

People with diabetes can check their bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. regularly at home using finger-prick glucoseA simple sugar that is an important source of energy in the body. testing.[2] This ongoing glucoseA simple sugar that is an important source of energy in the body. monitoring gives important information about how well bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels are being controlled.

Oral glucose tolerance test

Sometimes there is doubt as to whether or not a person has diabetes, even if their fasting bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. has been checked. In these cases, an oral glucose toleranceThe ability of the body to maintain a normal glucose level following the ingestion of glucose. test (abbreviated to OGTT) may be helpful.

This test involves fasting overnight (for at least eight hours), then drinking a standard glucoseA simple sugar that is an important source of energy in the body. solution (75g/2.6oz of glucoseA simple sugar that is an important source of energy in the body. in 300ml/10fl oz of water).

Blood samples are taken to check the level of glucoseA simple sugar that is an important source of energy in the body. in the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. both before and two hours after drinking the glucoseA simple sugar that is an important source of energy in the body. solution. In this way, a diagnosisThe process of determining which condition a patient may have. of diabetes may be made, or ruled out, by measuring the body's response to the glucoseA simple sugar that is an important source of energy in the body. given.[2,3]

Glycated haemoglobin

Haemoglobin is the oxygen-carrying pigment in red bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. cells. Glucose in the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. can bind to haemoglobin to produce glycated haemoglobinHbA1c, a measure of how well glucose levels have been controlled over the previous three months or so in a person with diabetes. It is expressed as a percentage. (also known as glycosylated haemoglobin), often abbreviated to HbA1cAn abbreviation for glycated haemoglobin, a measure of how well glucose levels have been controlled over the previous three months or so in a person with diabetes. It is expressed as a percentage..

The higher the level of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body., the more red cells will contain glycated haemoglobinHbA1c, a measure of how well glucose levels have been controlled over the previous three months or so in a person with diabetes. It is expressed as a percentage..

As red bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. cells have an average lifespan of 120 days, the proportion of them that contain glycated haemoglobinHbA1c, a measure of how well glucose levels have been controlled over the previous three months or so in a person with diabetes. It is expressed as a percentage. reflects how high bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels were, on average, during this time.

While bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. testing is very useful in the diagnosisThe process of determining which condition a patient may have. of diabetes, it is less useful in monitoring how well bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels are controlled in the long term as it is effectively a 'snapshot' - it shows what the current glucoseA simple sugar that is an important source of energy in the body. level is, but gives no information at all about the level of glucoseA simple sugar that is an important source of energy in the body. control over previous weeks or months.

Glycated haemoglobin, on the other hand, indicates how well glucoseA simple sugar that is an important source of energy in the body. has been controlled over the last three months or so, and so signals the risk of complications developing.[2,3]

While glycated haemoglobinHbA1c, a measure of how well glucose levels have been controlled over the previous three months or so in a person with diabetes. It is expressed as a percentage. is useful in monitoring glucoseA simple sugar that is an important source of energy in the body. control in diabetes, it is not sensitive enough to be used in diagnosing diabetes. Glycated haemoglobin can be difficult to assess sometimes - for example, in people who have anaemiaA reduced level of haemoglobin, which carries oxygen in the blood. Anaemia causes tiredness, breathlessness and abnormally pale skin. or women who are pregnant.[3]

Cholesterol and other lipids

Blood lipids are usually measured when diabetes is diagnosed, and regularly afterwards.[3] People with diabetes are at greater risk of cardiovascular disease and stroke, and disordered bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. lipids are an important risk factor for this.

Other blood tests

If you have been diagnosed with diabetes, it is important to have regular bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. tests to assess your liverA large abdominal organ that has many important roles including the production of bile and clotting factors, detoxification, and the metabolism of proteins, carbohydrates and fats., kidney and thyroid function.[3]

Urine tests

References

  1. http://www.nhsdirect.nhs.uk/
  2. Longmore M, Wilkinson I and Török E. Oxford Handbook of Clinical Medicine 2002; 5th edition.
  3. Boon NA, Colledge NR and Walker BR. Davidson's Principles and Practice of Medicine Churchill Livingstone Elsevier. 2006; 20th edition.