Children's Hyperinsulinism Charity

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Blood Glucose Levels

Most children with CHI will require their blood glucose to be monitored to ensure the child is not going hypoglycaemic. The individual’s blood glucose monitoring requirements and emergency hypoglycaemic protocol should be detailed in an individual care plan from their specialist team and it is vital that this is adhered to.

Blood glucose monitoring helps to detect patterns too such as illness, stress, poor feeding, hormonal changes etc. all which can influence blood glucose readings and it’s important to be aware of this.

A common method is by using a blood glucose monitor and lancing device. This gives a snapshot of what the blood glucose level is at that moment in time. Many children with CHI become used to this method as it becomes a part of their daily routine although for some it can be stressful.

More recently, we have seen the adoption of monitoring blood glucose with a CGM (Continuous Glucose Monitor), or Flash monitor. These are small devices worn just below the skin that measure glucose continually throughout the day and night.  CGM devices alert you to hypoglycaemic episodes via the receiver, whilst Flash monitors require you to scan your device over the sensor for measurement. 

Flash glucose monitor or CGMs measure the amount of sugar in the fluid surrounding your cells. This is called interstitial fluid. It’s not quite as accurate as a finger prick test as it lags behind blood sugar levels by up to 15 minutes. And the difference between the blood sugar and CGM or flash reading is more likely to be greater when you’re eating or exercising.  You may therefore also need to do finger prick tests.

For more information on monitoring blood glucose, CGMs and Flash monitors go to our management webpage:

Measuring Blood Glucose – Why is it important to keep levels above 3.5mmol/l ?

A blood glucose level less than 3.5mmol/l is considered as hypoglycaemia in babies and children with CHI.

Babies with CHI are constantly reliant on a normal circulating blood glucose concentration for normal function of the nerves and brain, hence the importance of maintaining blood glucose level above 3.5mmol/litre.

CHI is particularly damaging because apart from hypoglycaemia, the insulin suppresses the release of alternative fuels called ketones. Hence the brain is deprived of both glucose and ketones. Once the brain cells are deprived of these important fuels, they cannot make the energy they need to work and may result in seizures and coma.

It is this cell damage which can manifest as a permanent seizure disorder, learning disabilities, cerebral palsy or blindness in the long run. 

Alder Hey Patient Information Leaflet (Feb 2022 v4)

Glucometer and Little Boy

What can impact on blood sugar levels?


There are several factors that can contribute to a hypoglycaemic episode, such as:

Temperature – being too hot/cold can influence blood glucose levels as the body is working hard to regulate itself thereby using more energy – some CHI children cannot self-regulate.

Illness – fever, sickness, sore throat, earache, generally feeling unwell for example all influence blood glucose levels but all CHI different and you may see levels go higher than usual so be mindful of the child’s normal blood glucose range.

Fasting – if a child is not eating due to feeling unwell or may have a sore throat for example, this can cause blood glucose levels to change.

 Exercise – any type of exercise or activity that requires an increase in energy can affect blood glucose levels.

 Body changes – from losing/gaining teeth, hormones, developing body.

Using the brain – exams, tests, including spelling tests or any work that requires more concentration than usual.

Hospitalisations and appointments – many CHI children develop anxieties around these which can cause them stress and impact blood sugar levels.

Other causes of anxiety – school plays, show and tell in front of the class or an upcoming school test.

Changes in routine and environments  – school holidays, school trips,  playscheme etc.


It has been agreed nationally among all the tertiary children’s hospitals along with hyperinsulinism specialist centres to consider hypoglycemia as under 3.5mmol/l (63mg/dl). However, this may vary depending on your own child’s circumstances so please follow the care plan given by your medical team.

More guidance on the management of hypoglycaemia can be found in the UK National Guidelines:

mmol/L vs mg/dl

In the US and many other countries you may see blood glucose levels in mg/dl.  You can multiply the value in mmol/l by 18 to get the value in mg/dl.  However here is a basic conversion chart.  We have highlighted the blood sugar levels:
  • Green = normal levels
  • Amber = may be giving concern – follow instructions from doctor
  • Red = severe levels – urgent treatment required – follow instructions from doctor
mmol/l mg/dl
UK, Canada, Australia, China U.S, France, Japan, Israel, India
1 18
2 36
3 54
3.5 63
4 72
5 90
6 108
7 126
8 144
9 162
10 180
Please note that the higher numbers in this table are not appropriate reference for diabetic children or those who may be becoming diabetic after near-total pancreatectomy.  Please contact your clinician if your child is regularly having blood glucose readings above 10mmol/l or you are concerned that they may be becoming diabetic.
Cartoon Pancreas