Blood glucose monitoring

The purpose of this guideline is to provide guidance about blood glucose monitoring at Great Ormond Street Hospital (GOSH).

NOTE: We review our guidelines regularly and this guideline is now past its review date. The content of the guideline below may not reflect the most recent evidence based practice. Please use with caution.

Note: While this guideline refers to the ‘child’ throughout, all activities are applicable to young people.

When performing blood glucose monitoring, staff should be trained in both the theoretical and practical aspects, including the use of the glucose measuring device and instruction of quality control (Campbell 2008)(Rationale 1 and 2).

A normal blood glucose level is between approximately 4-7mmol/L (Gilbert 2009, Hanas 2004). Certain conditions/disorders work within different parameters as dictated by local policies and/or condition specific, eg congenital hyperinsulinism (Hussain 2007) (Rationale 3).

Staff should report blood glucose levels in mmol/L rather than describing the level as high or low (Rationale 4).

Standard monitoring

Blood glucose monitoring should commence within one hour of starting IV glucose of 10 per cent or higher. For neonates, this applies to any concentration of glucose including five per cent and must continue to be measured four hourly if within normal range of 4-7mmol/L and more frequently if outside this range (National Patient Safety Agency (NPSA) 2010. Medicine administration policy [available to GOSH staff internally on the document library]).

In exceptional circumstances, the clinician responsible for the child’s care may decide that an individualised clinical management plan is required. The rationale for this, together with the detailed clinical management plan, must be documented in the child’s health care record and reviewed daily.

If there is a requirement to reduce or increase the IV glucose concentration or the rate of administration, blood glucose monitoring should also occur within one hour of the changes (NPSA 2010).

If a child continues to be symptomatic and has either normal blood glucose levels or levels outside of the ranges 4-7mmol/L at the bedside despite appropriate interventions, a true glucose sample should be sent to the laboratory as directed by an experienced nurse or doctor (Rationale 9).

All blood glucose samples should be capillary or arterial and not from the venous administration line so to prevent contamination from the intravenous glucose solution (Gilbert 2009).

With very small babies on NICU it is not always possible to take a capillary sample due to the skin integrity and size of the neonate. It should be a consultant decision on whether a capillary sample is to be taken or if the sample can be taken from a line. Should the decision be to take the blood glucose sample from a line this must be documented in the patients’ healthcare record.

Any sample from a central line which is recorded ‘out or range’ must then result in a capillary sample being taken.

At handover, for neonates receiving a glucose infusion the most recent blood glucose level must be checked to ensure it is within acceptable limits in accordance with the clinical management plan (NPSA 2010).

Blood glucose monitoring is necessary for children:

  • Receiving intravenous or subcutaneous insulin (Rationale 6).
  • Receiving medication that can alter blood glucose levels, eg octreotide, diazoxide
  • Receiving intravenous glucose solutions, this includes parenteral nutrition
  • Nil by mouth and receiving only intravenous fluids for more than 12 hours
  • Commencing parenteral nutrition and during 'wind down' of cyclical parenteral nutrition until stable (Rationale 7)
  • With some endocrine and metabolic conditions, eg congenital hyperinsulinism and glycogen storage disease
  • With blood glucose levels outside of normal parameters 4-7mmol/L or parameters as specified by local policy and medical instruction specific to child‘s condition (Rationale 8)
  • Post-operatively as per local guidelines, ie procedure specific
  • Presenting with seizures and/or unexplained loss of consciousness
  • On intensive care standard monitoring of four-hourly blood glucose monitoring should be applied. However in exceptional circumstances an individual management plan may be required and is the responsibility of the lead consultant on a daily basis.

Neonatal risk factors for hypoglycaemia include:

  • intrauterine growth retardation
  • preterm
  • infants of insulin-dependent diabetic mothers
  • hypoxic ischaemic encephalopathy
  • hypothermia
  • polycythaemia
  • haemolytic disease of the newborn
  • other syndromes eg Beckwith-Weidermann
  • metabolic metabolism disorders, eg galactosaemia, glycogen storage disease

Medical teams responsible for individual patients must write a clear, daily plan in the patient care record to specify what blood glucose range is expected for these patients as well as a step-by-step plan to follow if the blood glucose is outside of these specified ranges (Rationale 3 and 4).

If the blood glucose level is outside of the parameters 4-7mmol/L, or if the child is symptomatic, such as pale lethargic, clammy and irritable or having seizures, the advice of an experienced nurse or doctor should be sought (Rationale 4).

Acknowledge the child or parent’s knowledge of the child’s condition and symptoms (Rationale 4 and 5).

Inform child and family

Inform the child and family of the following: 

  • that the monitoring of blood glucose is necessary 
  • the reason for monitoring
  • the implication of the result
  • what it entails
  • the proposed duration of the procedure

(Rationales 10, 11, 12 and 13)

Preparation

Standard or isolation precautions must be adhered to (Rationale 14).

If the child has an arterial line, this can be used for blood sampling (see clinical practice Guideline on arterial line sampling). 

If not, recommended puncture sites vary with age:

The back of the heel and tips of fingers should be avoided (Jain 2001)(Rationale 16).

The chosen puncture site should be continually rotated (Rationale 17).

Excessive squeezing should be avoided (Rationale 18).

White soft paraffin and alcohol impregnated wipes must not be used to prepare the child’s skin (Rationale 19 and 20). 

Age-appropriate lancing devices should be used to avoid tissue damage; these would include puncture devices as supplied by the Trust. A guillotine device should not be used for standard blood glucose monitoring as this can cause pain and tissue damage (Rationale 16, 18).

The appropriate use of distraction techniques, other play therapies and the level of involvement of the child should be assessed. The play specialist may need to be involved (Rationale 21 and 22).

The Accu-Chek® Inform II Glucose Meter is the meter currently used routinely within GOSH. All users must be trained in its use and have individual log-in cards. These must not be shared between staff (Rationale 23 and 24).

The Accu-Chek® Performa Glucose Meter is also used in the Trust, but is usually only found on the resuscitation trolleys. These do not require individual log-in details but users should still be trained in its use (Rationale 23).

When using a new pot of strips, the new ‘code chip’ supplied with the strips must be inserted into the Accu-Chek® Performa meter. The meter must then be quality control (QC) tested using the Accu-Chek® Performa glucose control solutions prior to the procedure of blood sampling as outlined in the Trust’s blood glucose training (Rationale 2 and 9).The ‘code chip’ is not required for the Accu-Chek® Inform II Glucose Meter and a QC test is not required for each new pot of strips as the strips are scanned with each patient test.

All QC testing of the Accu-Chek® Performa meter should be documented in the Accu-Chek® Performa record book. Where the meter is used at least daily it must be QC tested every 24 hours, otherwise it must be QC tested once per week. Ensure QC testing is within 24 hours before use (Rationale 23 and 24).

Quality Control (QC) testing of the Accu-Chek® Inform II Glucose Meter must be performed every twenty-four hours. This is required before the meter allows a patient test to be performed (Rationale 2 and 9).

QC testing must also be performed when the following occur:

  • meter is dropped. 
  • unexplained blood glucose levels versus clinical appearance of child
  • new batch of test strips or QC material for either Accu-Chek® Inform II or Accu-Chek® Performa meter

Gather the following equipment prior to blood sampling (Rationale 25):

  • Accu-chek® Inform II or Accu-chek® Performa meter 
  • Accu-chek® Performa test strips (in date and with lid on) (Rationale 26)
  • non-sterile gloves and an apron
  • non-sterile gauze - avoid use of cotton wool (Rationale 27)
  • sharps bin (Rationale 28)
  • blood glucose chart or appropriate alternative, eg CareVue
  • a retractable puncture device as supplied by the Trust (Rationale 28 and 29)

Obtaining a measurement

To obtain a blood glucose reading:

  • Wash and ensure site is clean and free from glucose contamination (Rationale 30).
  • Perform a hand wash (Rationale 31).
  • Put on non-sterile gloves and apron (Rationale 31).
  • Prepare meter immediately before sampling: Follow touch screen directions on the Accu-Chek® Inform II once logged in. Inserting strip into Accu-Chek® Performa meter turns it on automatically ready for use (Rationale 32).
  • Puncture the skin using retractable lancet device, or take the sample from an arterial line (see guideline for arterial line sampling) (Rationale 33). 
  • Wipe away first drop of blood (unless arterial) (Rationale 34). 
  • Gently squeeze or massage area to create tear drop size of blood (Rationale 35).
  • Place the edge of strip to the drop of blood.
  • Test area will draw in the blood sample.
  • Ensure yellow window on strip is completely filled with blood (Rationale 36).
  • Apply non-sterile gauze to the puncture site and apply pressure (Rationale 37 and 38).
  • Ensure bleeding has stopped and child is comfortable (Rationale 39).
  • Wait for result to be displayed on meter.
  • Read off result (displayed in mmol/L). The Accu-Chek® Inform II and Performa meter’s result range is 0.6 and 33.3mmol/L.
  • If the monitor reads 'LO' it indicates a blood glucose of <0.6 mmol/L. If the monitor reads 'HI' it indicates a blood glucose of >33.3 mmol/L.

Both situations are potential medical emergencies so check sampling techniques immediately and call for senior help. If the same result is obtained, send a true glucose blood sample to the laboratory and treatment will be as indicated by the medical team who should attend immediately. 

  • Record the result on the blood glucose chart or CareVue 2 (Rationale 40).
  • Dispose of used equipment according to the Waste Policy (Rationale 41).
  • Perform a hygienic hand wash (Rationale 42).
  • At handover, check the most recent blood glucose level is within acceptable limits in accordance with the clinical management plan (Rationale 8).
  • Regularly placing the Accu-Chek® Inform II meter in the docking units enables charging of the meter and uploading of results to the Chemical Pathology Lab.

Contraindications associated with extra-laboratory blood glucose measurement

Staff performing capillary blood glucose monitoring should be aware that the accuracy of results could be affected by the following clinical conditions (Medicine and Healthcare products Regulatory Agency 2010):

  • If peripheral circulation is impaired, collection of capillary blood from the approved sample sites is not advised as the results might not be a true reflection of the physiological blood glucose level.  This may apply in the following circumstances: severe dehydration as a result of diabetic ketoacidosis or due to hyperglycaemic hyperosmolar non-ketotic syndrome, hypotension, shock, decompensated heart failure NYHA Class IV, or peripheral arterial occlusive disease.
  • Blood concentrations of Galactose>0.83 mmol/L will cause overestimation of blood glucose results (normally galactoseis <0.28 mmol/L). Therefore glucometers must not be used in patients with a known or suspected diagnosis of galactosaemia. Such patients must be monitored using laboratory glucose results only. 
  • Haematocrit values should be between 10-65%. 
  • Intravenous (IV) infusion of ascorbic acid will cause overestimation of results. 
  • Lipaemic samples (triglycerides) in excess of 20.3 mmol/L may produce elevated results.

On completing the procedure

After accurately recording the blood glucose level in the appropriate chart, review the result against the normal range of 4-7mmol/L and also the required range for the specific child according to local policy or medical instruction.  

If the result is out of range, inform an experienced nurse or doctor of the result and commence interventions as directed (Rationale 43).

Inform the child/family of the result and explain the implications (Rationale 44).

A damp cloth should be used to clean the meter. Surface wipes can be used but please wipe off excess residue from the meter to prevent build up on the barcode reader of the Accu-chek® Inform II meter or display window of the Accu-Chek® Performa. The meter should be cleaned after every patient use (Rationale 42). Do not immerse in water (Rationale 45).

There should be no attempt to clean the optics or inside the meter (Rationale 46).

Chemical Pathology must be contacted (ext 1443) if the Accu-chek® meter has malfunctioned and if additional support or equipment is required.

Important note

Patient own meters and lancet devices may be used by the child or parent to gain practice in the technique of blood glucose monitoring or promote involvement, but Trust meters (Accu-Chek® Inform II meter or Accu-Chek® Performa) must also be used  as they are quality controlled as per hospital policy and can be deemed accurate.

Blood glucose monitoring sheet

blood glucose monitoring sheet

Rationale

Rationale 1: To achieve an accurate reading. Untrained staff may obtain inaccurate or misleading results that can lead to incorrect management and adversely affect the patient.
Rationale 2: To meet the manufacturer’s recommendations.
Rationale 3: Children with Hyperinsulinism should not have blood glucose of less than 3.5mmol/L without intervention as are unable to produce alternative fuel sources such as ketones and are therefore at high risk of brain damage (Hussain et al 2007). A lower level of 3.0mmol/L (Campbell 2008) may be accepted for children with other conditions before intervention but the named consultant for individual patients must direct this.
Rationale 4: To initiate appropriate intervention and management.
Rationale 5: To promote involvement and enable partnership in care.
Rationale 6: Monitoring is necessary for dose adjustment.
Rationale 7: To avoid blood glucose levels rebounding above and below normal levels as a result of change to rates and subsequently a rapid change to glucose administration.
Rationale 8: To initiate appropriate intervention and management.
Rationale 9: To exclude meter error and incorrect results.
Rationale 10: To obtain informed consent.
Rationale 11: To aid efficiency.
Rationale 12: To promote safety.
Rationale 13: To promote involvement and enable partnership in care.
Rationale 14: To minimise the risk of cross infection.
Rationale 15: To avoid affecting the pincer grip and fine motor skills.
Rationale 16: To prevent damage to underlying structures, eg nerve endings (Jain et al, 2001; Naughten, 2005).
Rationale 17: Continued use of the same puncture site can lead to the area becoming sore and the development of calluses (Naughten 2005).
Rationale 18: To prevent pain and tissue damage (Naughten 2005).
Rationale 19: Alcohol toughens the skin when used frequently.
Rationale 20: Alcohol and whit soft paraffin can interfere with strip and meter analysis and may give incorrect results.
Rationale 21: To minimise the child’s distress.
Rationale 22: To promote involvement.
Rationale 23: Untrained staff may obtain inaccurate or misleading results that can lead to incorrect management and adversely affect the patient.
Rationale 24: The Accu-Chek® Inform II Glucose Meter is intended to provide an audit trail; therefore identification of each user is important.
Rationale 25: To aid efficiency.
Rationale 26: Out-of-date strips and exposing test strips to moisture may give incorrect results.
Rationale 27: Cotton wool fibres can interfere with strip and meter analysis and may give incorrect results.
Rationale 28: To promote safety and prevent needle stick injury.
Rationale 29: To achieve optimum depth of penetration.
Rationale 30: To prevent incorrect test results.
Rationale 31: To minimise the risk of cross infection.
Rationale 32: To facilitate analysis.
Rationale 33: To obtain blood sample.
Rationale 34: To reduce haemolysis and ensure circulating blood is measured.
Rationale 35: To encourage blood flow to the site.
Rationale 36: To obtain accurate and reliable results.
Rationale 37: To prevent further bleeding.
Rationale 38: To prevent haematoma formation.
Rationale 39: To promote safety and comfort.
Rationale 40: To maintain accurate records.
Rationale 41: To adhere to hospital policy.
Rationale 42: To minimise risk of cross infection.
Rationale 43: To initiate appropriate intervention and management.
Rationale 44: To promote involvement and enable partnership in care.
Rationale 45: To minimise the risk of cross infection.
Rationale 46: To adhere to manufacturer’s instructions. 

References

Reference 1: 
Campbell IW (2008) Hypoglycaemia (low blood sugar) in diabetes. netdoctor (e-pub) 

Reference 2: 
Gilbert C (2009) Investigation and management of congenital hyperinsulinism. British Journal of Nursing 18 (20: 1256-1260. 

Reference 3:
Hanas R (2004) Type 1 diabetes in children, adolescents and young adults. Class Publishing, London. Edition 2nd edition. 

Reference 4: 
Hussain K, Blackenstein O, De Lonlay P and Christessen HT (2007) Hyperinsulinaemic hypoglycaemia: biochemical bias and the importance of maintaining normoglycaemia during management. Archive of Diseases in Childhood 92 (7): 568-570. 

Reference 5:
National Patient Safety Agency (2010) Prevention of over infusion of intravenous fluid* and medicines in neonatesViewed on: 23/09/2014.

Reference 6:
Naughten F (2005) The heel prick: how efficient is common practice? RCM Midwives 8 (3): 112-4.

Reference 7: 
Jain A, Rutter N and Ratnayaka M (2001) Topical amethocaine gel for pain relief on heel prick blood sampling: a randomised double blind controlled trial. Archives of Diseases in Childhood, 84: 56-59. 

Reference 8: 
Medicine and Healthcare Products Regulatory Agency (2010) Management and use of IVD point of care test devices - DB2010(02) Viewed on: 28/06/2010. 

Document control information

Lead Author(s)

Clare Gilbert, Clinical Nurse Specialist, Hypoglycaemia

Additional Author(s)

Kate Morgan, Clinical Nurse Specialist, Hypoglycaemia
Annette Rathwell, Clinical Nurse Specialist, Neonates
Nattallie Alwash, Ward Manager, Medicine, Diagnostic, Therapeutic Services
Samantha Drew, Clinical Nurse Specialist, Diabetes
Hannah Gordon, Clinical Nurse Specialist, Diabetes
Nikola Costa, Senior Clinical Scientist

Document owner(s)

Nattallie Alwash, Ward Manager, Medicine, Diagnostic, Therapeutic Services

Approved by

Guideline Approval Group

Reviewing and Versioning

First introduced: 
31 January 2002
Date approved: 
22 September 2014
Review schedule: 
Three years
Next review: 
22 September 2017
Document version: 
4.0
Previous version: 
3.0