Sliding scale (variable rate intravenous insulin infusion)
What is an insulin ‘sliding scale’?
A sliding scale (or the real name: variable rate intravenous insulin infusion, sometimes abbreviated to ‘VRIII’) is an intravenous drip with insulin and glucose, two separate lines which enter the hand or wrist via one intravenous needle.
The sliding scale helps to stabilise blood sugar levels by adding glucose if levels drop too low, or by adding insulin if your levels raise too high straight into the bloodstream.
Blood sugar levels are monitored frequently by manually testing (finger pricking) and the sliding scale is adjusted manually as required.
Use of the sliding scale with gestational diabetes:
1. During hospital admittance when blood glucose levels are not under good control
Some ladies may be put onto a sliding scale if they have erratic blood sugar levels, high or low. This may be due to illness or severe sickness, such as when suffering with hyperemesis gravidarum (HG), where the mother is unable to keep down food or fluids.
A sliding scale may be used if a mother is suffering from high blood sugar levels, ketosis or diabetic ketoacidosis (DKA).
2. During hospital admittance for steroid injections
Some mothers with gestational diabetes will be advised to have steroid injections to help mature their baby’s lungs. This is because there is a higher risk of respiratory problems in premature babies, babies delivered by caesarean section and babies born to mothers with gestational diabetes before approximately 38 weeks gestation.
These steroid injections can cause high, uncontrollable blood sugar levels and so many diabetic mothers will have their blood sugar levels monitored closely (in some cases hourly) and a sliding scale may be used to help control and lower the blood sugar levels throughout this time. This may be for a 24 hour period as steroid injections are usually given twice, often 12 hours apart.
Please note: Not all hospitals admit patients or use a sliding scale whilst giving steroid injections.
3. During induction and/or labour
Sliding scales may be used during induction and/or labour for some ladies with diabetes.
Differences of use during induction and/or labour in different hospitals:
- In some hospitals a sliding scale will be used as part of their Trust or hospital policy for all women with gestational diabetes
- Other hospitals will use a sliding scale for insulin controlled mothers only
- and some will only use a sliding scale if they see blood sugar levels drop or rise to a certain threshold level
The NICE guidelines around the use of a sliding scale during labour are as follows:
Blood glucose control during labour and birth
1.4.10 Monitor capillary plasma glucose every hour during labour and birth in women with diabetes, and ensure that it is maintained between 4 and 7 mmol/litre. [2008, amended 2015]
1.4.11 Intravenous dextrose and insulin infusion should be considered for women with type 1 diabetes from the onset of established labour. 
1.4.12 Use intravenous dextrose and insulin infusion during labour and birth for women with diabetes whose capillary plasma glucose is not maintained between 4 and 7 mmol/litre. [2008, amended 2015]
Is a sliding scale necessary for all mothers with gestational diabetes during labour?
If you have stable, well controlled blood sugar levels throughout pregnancy and labour, then a sliding scale is not going to be necessary. If however, there are concerns over the control of your blood sugar levels, then it would be advisable.
But if a sliding scale is being used as per a hospital ‘policy’ i.e. just because you have a label of gestational diabetes on your maternity notes, rather than assessing your individual needs, then you may want to discuss the option of only using a sliding scale if and when necessary as part of your birth plan.
Many mothers with gestational diabetes are able to adequately control their own blood sugar levels throughout labour by monitoring (finger pricking) and continuing with good choice of diet, medication and or insulin as required.
For a list of suitable snacks to eat during induction then please take a look at our hospital bag list for ideas.
A large amount of mothers diagnosed with gestational diabetes deliver their babies without the need or use of an insulin sliding scale IV in the UK and ROI.