Glucose Intolerance

Glucose intolerance is an umbrella term for metabolic conditions which result in higher than normal blood glucose levels – hyperglycemia.

Western lifestyles have seen glucose intolerance become more common year on year.

What conditions are denoted by glucose intolerance?

Conditions which can be considered as glucose intolerance include:

What is glucose intolerance?

Glucose intolerance includes anyone with either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT).

With the World Health Organisation’s definitions for IFG and IGT, glucose intolerance is defined as: [46]

  • A fasting blood glucose level of above 6.0 mmol/L or
  • A blood glucose level of over 7.8 mmol/L 2 hours after consuming 75g of glucose.

Symptoms of glucose intolerance

The symptoms of glucose intolerance match those of type 2 diabetes:

The NHS states that not everyone will get these symptoms and symptoms may not be so severe.

Glucose intolerance test

A number of tests can be used to diagnose forms of glucose intolerance.

Test performed to diagnose glucose intolerance include:


Glucose intolerance is term for metabolic conditions which result in high blood glucose levels.
Pre-diabetes, type 2 diabetes, impaired fasting glucose and impaired glucose tolerance are all conditions which fall under the term glucose intolerant.

Glucose intolerance is defined by the World Health Organisation as:

  • A blood sugar level of 6.0 mmol/l or above whilst fasting
  • A blood glucose level of over 7.8 mmol/l 2 hours after consuming 75g of glucose

The figures above are based on the assumption that people are not taking blood glucose lowering medication. The symptoms of glucose intolerance may not be so easy to spot. The symptoms may include:

  • Feeling thirsty
  • Being tired or lethargic
  • Needing to urinate more than usual
  • Itchiness around the genitals

People with impaired glucose tolerance are more likely to notice symptoms after meals. Whereas people with impaired fasting glucose will notice the symptoms through other parts of the day including during the night.

Glucose intolerance will often be diagnosed by a fasting plasma glucose test or by a glucose tolerance test. A plasma glucose test is when a blood sample is take, usually from your arm, and the blood glucose levels measured. A glucose tolerance test involves taking a set amount of glucose orally, usually 75g of glucose, and then taking your blood glucose levels over regular periods of time over the next few hours.

Glucose intolerance can be treated through diet and lifestyle changes or with assistance from anti-diabetic medication, such as tablets and/or insulin. Your doctor will measure your long term blood glucose control via an HbA1c test.

Your doctor may also prescribe you with blood glucose testing supplies to allow you to make diet choices and to indentify and prevent high or low blood glucose levels.

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Treatment for glucose intolerance

Treatments for glucose intolerance will either require lifestyle changes or a combination of lifestyle changes and anti-diabetic medication

Lifestyle changes involve taking part in regular physical activity, aiming to lose weight, if appropriate, and cutting down on smoking and alcohol as necessary.

If medication is advised, most people will start on a drug, taken in tablet form, called metformin

Some people may need to take additional or alternative medication.

Glucose intolerance diet

The diet recommended by the NHS follows general healthy eating advice.

The NHS recommends eating a balanced diet based on whole grain foods, rich in fruit and vegetables and low in sugar, salt and saturated fat.

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