Staying safe on an insulin pump

Insulin pump therapy is a safe and effective way of treating diabetes. However due to the way the insulin is delivered, problems may deteriorate more quickly than when using an insulin pen for injections. Therefore it is important that the safety guidelines in this leaflet are followed. The following areas will be addressed:

  1. Blood glucose testing.
  2. Cannula care.
  3. Reasons for raised blood glucose levels.
  4. Managing high blood glucose levels.
  5. Managing a pump failure.

1. Blood glucose testing

  • In order to continue funding for pump therapy you must test your blood glucose at least four times per day. This is the best and quickest way of noticing potential problems.
  • If blood glucose levels are above 14mmol/L see guidance below.
  • Always check your blood glucose levels before bed and never go to bed with an unexplained blood glucose of more than 14mmol/L as problems can escalate quickly overnight.

2. Cannula care

  • Good cannula care is essential to make sure the insulin is delivered correctly.
  • Change metal cannula every two days, sooner if required.
  • Change plastic cannula every two to three days, sooner if required.
  • Remember to test your blood glucose before and two hours after changing a cannula.
  • Do not change cannula just before bed - preferably latest before evening meal.
  • Changing a cannula before a meal is best so you can check whether the bolus has been effective.
  • Remember to always carry a spare cannula / set and an insulin pen in case the cannula or pump fails unexpectedly.

3. Reasons for high blood glucose levels

There are many reasons why blood glucose levels can be high, consider the following potential causes, including:

General causes

  • Too little insulin.
  • Illness.
  • Hormonal changes.
  • Medication e.g. steroids.
  • Reduced activity.
  • Stress, anger or anxiety.
  • Reduced effectiveness of insulin (for example if the insulin has become too hot or cold).

Infusion set

  • Cannula inserted into a lumpy injection area.
  • Infusion set empty / not primed.
  • Air bubbles in cannula / tubing / cartridge.
  • Cannula blocked (pump may not alarm).
  • Infusion set bent or not correctly inserted.
  • Infusion set leaking or not correctly connected.
  • Cannula not changed often enough as per cannula care guidelines.
  • Cannula moved out of position – this can occasionally happen, especially at night.

Insufficient insulin given

  • Missed dose at mealtime.
  • Insufficient dose for carb intake.
  • Insulin for snacks not given.
  • Not testing often enough to inform insulin adjustment.
  • Not correcting high blood glucose level.
  • Not entering correct blood glucose level into pump.
  • Too much carbohydrate following a hypo.

Pump problems

  • Insulin pump accidentally left in ‘suspend’ mode.
  • Pump not reconnected following disconnection.
  • Basal rate too low.
  • Cartridge empty.
  • Battery flat.
  • Pump failure.

4. Managing high blood glucose

If your blood glucose is higher than 14mmol/L twice in a row (in a three to four hour period) check your pump and infusion set.

If you find a logical cause for the high blood glucose, take your normal correction dose through the pump. See ‘reasons for high blood glucose levels’ above.

If you cannot find a logical cause for the high blood glucose, check for ketones.

If you have two unexplained blood glucose levels over 14mmol/L, always:

  • Check for ketones.
  • Take your correction dose by syringe or pen.
  • Change your infusion set.

Managing ketones

If you don’t have a blood ketone monitor please request one from your diabetes team.

Blood ketones 0.0 – 0.6mmol/L:

  • Give your insulin correction dose through your pump.
  • Recheck blood glucose and ketones in two hours.
  • If your blood glucose is falling, this is a good sign, but continue to monitor your levels closely throughout the day.
  • If they are not falling, take another correction dose (this time by syringe or pen) and continue to monitor.
  • If after 24 hours blood glucose remains above 14.0mmol/L, contact DSNs or seek medical help.

However – If ketones rise, see below

Blood ketones 0.6 – 1.4mmol/L or above:

  • Give double your usual correction dose by syringe or pen.
  • Change your insulin and infusion set.
  • Begin to drink plenty of water, aim for one medium glass every half an hour.
  • Recheck blood glucose and ketones in two hours.
  • If your blood glucose and ketone levels are falling, you must continue to monitor to be sure the new infusion set is working.

Blood ketones not coming down despite previous advice or ketones more than 1.5mmol/L:

Take another injected double correction dose and call the diabetes team during working hours (8am - 4pm) for urgent medical advice.

Out of hours take another injected doubled correction dose and come to the emergency department at your nearest hospital as you are likely to need an infusion of insulin.

In case of pump failure

  1. You will need to start using insulin pens to deliver your insulin – ensure you always have in date pens of Novorapid/Humalog or Fiasp and Humulin I (intermediate acting insulin) available.
  2. Convert your total insulin pump basal (background) insulin to twice daily injections at breakfast and bed time. For example, if you take 24 units of basal insulin (background) – take 12 units of injectable insulin (Humulin I) at breakfast time and 12 units at bedtime.
  3. Continue to give short acting insulin with your meals using your insulin to carbohydrate ratio.
  4. On the day your pump arrives, please do not take the breakfast Humulin I and continue as normal with your usual rapid acting insulin. Restart your pump around lunchtime (or later). You may need a temporary basal reduction in the first few hours of pump therapy.
  5. For most patients taking Humulin I and usual rapid acting insulin whilst awaiting pump replacement, blood glucose levels will be higher than normal. The aim of this treatment is to prevent you getting ketones and to prevent hypoglycaemia, not necessarily achieving perfect blood glucose control.
  6. If your blood glucose levels rise above 14mmol/L please remember to check for ketones and follow the advice in this leaflet.


If you or the individual you are caring for need support reading this leaflet please ask a member of staff for advice.

How to contact us:

Department of Diabetes and Endocrinology
Southmead Hospital
Brunel building
Bristol, BS10 5NB

0117 414 6430 (Secretary, 8.30am to 4.30pm)
0117 950 5050 (Switchboard, ask for bleep 9315)
0117 414 6413 (Lynn Sawyer, specialist dietitian)
0117 414 6428 (Julie Emsley, specialist nurse)
0117 414 6414 (Sarah Reynolds, specialist nurse)

© North Bristol NHS Trust. This edition published September 2019. Review due September 2021. NBT003035

Staying safe on an insulin pump