The most important reason for having a blood glucose meter is to prevent or pick up on low blood sugar levels.

If you need to take insulin or medicine like gliclazide (a sulphonylurea) or a glinide, there may be times when your blood glucose levels drops below 4mmol/L (72mg/dL) and this can make you feel very unwell and drowsy.

Anyone at risk of episodes of hypoglycaemia like that should get a free blood glucose monitor from their GP.

Research studies involving people living with type 2 diabetes have not shown any difference in blood glucose levels between people who have blood glucose monitors and people who don’t. So blood glucose monitors are not essential and for most people, they will not be worth spending money on.

If you are not on insulin, gliclazide or a glinide, your blood glucose levels should not drop below 4mmol/L (72mg/dL) and you should not be at risk of hypoglycaemia. That is why the NHS does not routinely provide free blood glucose meters for other people with type 2 diabetes.

However, blood glucose monitors can be useful for understanding the impact of food, exercise and medicines on your body. Used correctly, blood glucose monitors can be a powerful tool to help you appreciate how physical activity, medication and carbohydrates make your blood glucose levels go up and down. If you like to keep track of your blood glucose levels or want to understand the immediate effects of changing your diet and exercise habits - you may choose to buy a meter and keep a record of your readings.

When should I measure my blood sugar levels?

Blood glucose levels can be measured:

  • Before breakfast (fasting)
  • Before a meal (pre-prandial)
  • 2 hours after a meal (post-prandial)
  • If you are worried about hypoglycaemia

For guidance about checking blood glucose levels when driving, you can find advice from Diabetes UK here.

What are normal blood glucose levels?

For very tight control, fasting blood glucose levels should be between 5 to 7 mmol/L (90 to 126 mg/dL), and readings 2 hours after eating should be between 7 and 9 mmol/L  (126 to 162 mg/dL).

That will not be appropriate for everyone, so your doctor may advise that it may be sensible to aim for slightly higher levels e.g. below 11 mmol/L (198 mg/dL) 2 hours after meals.

Dangerous blood glucose levels are levels below 4 mmol/L (72 mg/dL) or above 20 mmol/L (360 mg/dL) and you should seek advice from a healthcare professional if your blood glucose levels are too low or too high.

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Reviewed by Dr. Kingshuk Pal