Diabetes mellitus type 1 - blood glucose monitoring of hospitalised patients
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Goal of capillary blood glucose monitoring
The aim of blood glucose monitoring within the inpatient setting is to:
- Monitor daily blood glucose control and allow insulin dose adjustment
- Detect hypoglycaemia or hyperglycaemia so that appropriate treatment can be initiated as required
Patients with diabetes mellitus will often use their own blood glucose meter and finger pricking device to undertake blood glucose monitoring within the hospital setting.
Recommended testing times
Testing times will vary between patients however generally testing times are as follows:
- Before breakfast (to optimise basal insulin requirements)
- Before lunch
- Before evening meal
- Before bed (to prevent nocturnal hypoglycaemia)
- Midnight (to detect nocturnal hypoglycaemia)
- 0400 (to detect nocturnal hypoglycaemia)
- Test if hypoglycaemia suspected (Blood glucose level <3.9mmol/L)
- Test again 10-15 minutes after an episode of hypoglycaemia to confirm glucose within target range.
Target ranges for capillary blood glucose testing
Target blood glucose levels are recommended to try and keep blood glucose levels as near as possible to the normal range, without the risk of frequent hypoglycaemia.
At night the target range is set a little higher to reduce the risk of hypoglycaemia at night.
Realistically patients will only achieve 60 - 80 percent of
blood glucose levels within the target range. Levels outside the
target range should be described as "high" or "low".
Target blood glucose levels can vary between patients but generally for children and adolescents are as follows:
|Before meals||4 - 7 mmol/L|
|After meals (at 2 hours)||5 - 10 mmol/L|
|At bedtime||6 - 10 mmol/L|
|At 4am||5 - 8 mmol/L|
Blood glucose targets may be set higher for infants and children under 5 years as follows:
|Before meals||5 - 10 mmol/L|
|After meals (at 2 hours)||6 - 10 mmol/L|
|At bedtime||6 - 12 mmol/L|
|At 4am||5 - 8 mmol/L|
Blood glucose meter usage
- Most meters should give an error code if too small a drop of blood is used
- Meters have a temperature range within which they are designed to operate and can be less accurate if used outside this range
- No meter is as accurate as a laboratory blood test. Accuracy is within 10 - 15% when used correctly however there will be minor variation between different meters
Lancet device usage
- Patient-own lancet devices are single-patient use only
- Patient-own lancet devices allow variation in the depth of penetration
- Patient-own lancet needles for lancet devices must be changed every 3 days to avoid discomfort and damage to the fingers
- Hospital issue lancet devices are single-use only
- Wash and dry hands thoroughly prior to undertaking a blood glucose test
- Hands should be warm prior to undertaking a blood glucose test
- Recommended site: outer edge of the fingertips, avoid pad or tip of fingers.
Continuous blood glucose monitoring (CGM) usage
Minimally invasive devices are available that measure subcutaneous interstitial fluid glucose every 1-5 min. A minimum of 3 additional blood glucose levels/day manually entered into the CGM device are generally required to calibrate the CGM. Once calibrated, the sensor communicates wirelessly with either an insulin pump or receiving device which displays and stores blood glucose data.
CGM measures "tissue" glucose as opposed to "blood glucose". In most situations there is good correlation between tissue and blood glucose levels however at time of rapidly changing blood glucose levels, there may be a significant lag in the sensor response and the correlation becomes less accurate. When wearing the CGM, confirmation by capillary blood glucose testing must be undertaken before treating either hyperglycaemia or hypoglycaemia.
Glycated haemoglobin HbA1c
Glucose becomes irreversibly attached to the molecule of haemoglobin during the life cycle of the circulating red cell (which is approximately 120 d) forming glycated haemoglobin (HbA1 or HbA1c). HbA1c reflects levels of glycaemia over the preceding 4-12 week period, weighted toward the most recent 4 weeks.
HbA1c monitoring has been shown to be the most useful measure in evaluating metabolic control and is the only measure for which good data are available in terms of its relationship with later microvascular and macrovascular complications.
An HbA1c target of <7.5% (58 mmol/mmol) is recommended for all patients younger than 18 years.
Information for Families
- ISPAD Clinical Practice Consensus Guidelines 2014 Compendium. Assessment and monitoring of glycemic control. Rewers, MJ, Pillay, K, de Beaufort C, Craig ME,
- Hanas, R, Acerini, CL, Maahs, DM. Pediatric Diabetes 2014: 15 (Suppl. 20): 102-114.
- National Evidence-Based Clinical Care Guidelines for Type 1 Diabetes in Children, Adolescents and Adults Craig, ME, Twigg, SM, Donaghue, KC, Cheung, NW, Cameron, FJ, Conn, J, Jenkins, AJ, Silink, M, for the Australian Type 1 Diabetes Guidelines Expert Advisory Group. Australian Government Department of Health And Ageing, Canberra 2011.
Did you find this information helpful?
- Date last published: 23 May 2016
- Document type: Clinical Guideline
- Services responsible: Paediatric Endocrinology
- Author(s): Craig Jefferies, Fran Mouat, Rosalie Hornung
- Owner: Rosalie Hornung
- Editor: Greg Williams
- Review frequency: 2 years
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