Low blood glucose (hypoglycaemia)

Low blood glucose (also known as hypoglycaemia or hypo) can also occur in insulin pump users. You should always treat low blood glucose immediately. When you feel hypo symptoms take your rapid-acting carbohydrate as quickly as possible. Reasons for low blood glucose can include:

  • Overestimating carbohydrates and giving too much insulin as a bolus
  • Giving a large bolus with food (may be better to use a different type of bolus)
  • Slow digestion of food
  • Basal rate too high
  • More activity than usual without setting a temporary basal rate
  • Over correction for high blood glucose value
  • Alcohol consumption
  • Stress causes hypos in some people
  • Around time of menstrual cycle
  • Incorrect insulin to carbohydrate ratio
  • Hot weather

Even if you do not have symptoms, if your blood glucose level is below 4.0 mmol/l you must treat it with a rapid-acting carbohydrate. Stop and treat quickly. Follow the treatment guidelines below. Repeat blood glucose after 5–10 minutes, if blood glucose remains low take your rapid-acting carbohydrate again.

For blood glucose below 4.0 mmol/l: treat with rapid-acting carbohydrate.

For blood glucose below 4.5 mmol/l but above 4 mmol/l: eat carbohydrates.

If low blood glucose (‘hypo’) occurs: Action
Within 1 hour of next meal 15–20 g rapid-acting carbohydrate
1–2 hours until next meal 15–20 g rapid-acting carbohydrate (consider an additional 10 g medium-acting carbohydrate)
More than 2 hours until next meal 15–20 g rapid-acting carbohydrate (consider an additional 20 g medium-acting carbohydrate)

Examples of rapid-acting carbohydrate include:

  • 200 ml of concentrate orange juice
  • 4–5 jelly babies
  • 4–5 glucose tablets

Examples of medium-acting carbohydrate include:

  • 1 slice bread sandwich (15 g) or 2 slice bread sandwich (30 g)
  • Fruit or glass of milk or 1 biscuit (10–15 g)
  • Your next meal

The hypo treatment flowchart is available here.

You should consider the cause of your hypo and how to use pump features in future to either prevent it, reduce its severity or assist in its treatment. The following factors can contribute to an increased risk of hypoglycaemia in insulin pump users:

  • Not using a temporary basal reduction (TBR) when needed
  • Delayed hypo post-exercise – have you used temporary basal reduction (TBR) for long enough?
  • Alcohol may cause nocturnal or delayed hypo – have you considered temporary basal reduction (TBR)?
  • Change of cannula site from an area of lipohypertrophy (lumpy skin) to normal skin
  • Weight loss or change in lifestyle

Always try and think of the reason for your hypo so that you can learn from your experience. It is not necessary to stop the pump if you are having a hypo but it is important to treat it quickly. You will not need longer acting carbohydrates such as a biscuit or a sandwich.

Remember: if you are having frequent episodes of hypoglycaemia, or are unable to treat the hypo yourself, you should contact your diabetes team for advice.

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