oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
The role of glucose monitoring
Self-monitoring of blood glucose is considered as an effective tool for the management of diabetes, especially for those who require insulin treatment.
Self-monitoring gives regular feedback for the patient, but decisions on both the method and frequency of testing need to be made on an individual basis. Monitoring is only useful if it is used to inform decisions (eg, adjusting tablets or insulin dosage).
Diabetes empowerment improves diabetes self-care behaviours (including diet, physical activity, blood glucose monitoring, and foot care). Studies have shown that when patients perform self-monitoring, support through appropriate educational initiatives is critical to ensure that patients understand the rationale for self-monitoring of blood glucose. See also the separate article on Diabetes Education and Self-management Programmes.
Methods of monitoring glucose
Various methods of glucose monitoring are available, including HbA1c measurement, blood glucose monitoring and urine testing. Note: urine testing is not recommended but may be useful for some patients with diet- or tablet-controlled type 2 diabetes mellitus - for example, as a warning sign of high glucose levels when unwell.
Blood glucose monitoring
Blood glucose monitoring using a meter gives a direct measure of the glucose concentration at the time of the test and can detect hypoglycaemia as well as hyperglycaemia.
Patients should be properly trained in the use of blood glucose monitoring systems and to take appropriate action on the results obtained. Inadequate understanding of the normal fluctuations in blood glucose can lead to confusion and inappropriate action.
Although glucose meters are not prescribable at NHS expense, they are often provided free to patients from the manufacturers on the basis of income made from the testing strips, which are prescribable at NHS expense and each type of testing strip is specific to each monitor.
Urine glucose testing
- Urine testing is best undertaken in the morning before breakfast. The bladder should be emptied when the person first gets up from bed and a sample, passed 30 minutes later, tested. Tests done at this time should be negative. Testing can also be done two to three hours after a meal, when blood glucose will have been at its highest.
- Urine testing gives a less accurate picture of blood glucose than blood testing and does not give an indication of the blood glucose level because the urine tested may have been produced several hours before the test. Urine tests also don't indicate if blood glucose is too low.
- The results of urine testing are also dependent on the individual person's renal threshold for glucose.
- Urine testing involves comparing a colour change on the urine testing strip and is not suitable for the visually impaired.
Urine ketone testing
People with diabetes should also routinely be given urine testing strips so they can test their urine for ketones (particularly if their blood glucose is high (usually over 15 mmol/L) or if they have any symptoms of illness) and advised to seek medical advice if ketones are present.
Continuous glucose monitoring
Subcutaneous continuous glucose monitoring (CGM) machines show real-time glucose on the monitor every five minutes and have alarms to indicate hypoglycaemia and hyperglycaemia. However, there is no clear consensus about the clinical indications for CGM in actual clinical practice.
A Cochrane review found that there is limited evidence for the effectiveness of real-time CGM use in children, adults and patients with poorly controlled diabetes. However there were indications that higher compliance of wearing the CGM device improved glycosylated HbA1c level to a larger extent.
Type 1 diabetes
- Self-monitoring of blood glucose levels should be used as part of an integrated package that includes appropriate insulin regimens and education to help choice and achievement of optimal diabetes outcomes.
- Self-monitoring skills should be taught close to the time of diagnosis and initiation of insulin therapy.
- Self-monitoring results should be interpreted in the light of clinically significant life events.
- Self-monitoring should be performed using meters and strips chosen by adults with diabetes to suit their needs, and usually with low blood requirements, fast analysis times and integral memories.
- Structured assessment of self-monitoring skills, the quality and use made of the results obtained and the equipment used should be made annually. Self-monitoring skills should be reviewed as part of annual review, or more frequently according to need, and reinforced where appropriate.
- Adults with type 1 diabetes should be advised that the optimal frequency of self-monitoring will depend on:
- The characteristics of an individual's blood glucose control.
- The insulin treatment regimen.
- Personal preference in using the results to achieve the desired lifestyle.
- Monitoring using sites other than the fingertips (often the forearm, using meters that require small volumes of blood and devices to obtain those small volumes) cannot be recommended as a routine alternative to conventional self-blood glucose monitoring.
Type 2 diabetes
National Institute for Health and Care Excellence (NICE) recommendations for patients with type 2 diabetes
- Offer self-monitoring of plasma glucose to a person newly diagnosed with type 2 diabetes only as an integral part of his or her self-management education.
- Discuss its purpose and agree how it should be interpreted and acted upon.
- Self-monitoring of plasma glucose should be available:
- To those on insulin treatment.
- To those on oral glucose-lowering medications to provide information on hypoglycaemia.
- To assess changes in glucose control resulting from medications and lifestyle changes.
- To monitor changes during intercurrent illness.
- To ensure safety during activities, including driving.
- Assess at least annually and in a structured way:
- Self-monitoring skills.
- The quality and appropriate frequency of testing.
- The use made of the results obtained.
- The impact on quality of life.
- The continued benefit.
- The equipment used.
- If self-monitoring is appropriate but blood glucose monitoring is unacceptable to the individual, discuss the use of urine glucose monitoring.
People with type 2 diabetes who are not using insulin
Although self-monitoring of blood glucose has been found to be effective for patients with type 1 diabetes and for patients with type 2 diabetes using insulin, evidence suggests that self-monitoring of blood glucose is of limited clinical effectiveness in improving glycaemic control in people with type 2 diabetes on oral agents or diet alone.
A Cochrane review found that the overall effect of self-monitoring of blood glucose on glycaemic control in patients with type 2 diabetes who are not using insulin is small up to six months after initiation and subsides after 12 months. There was no evidence that self-monitoring of blood glucose affected patient satisfaction, general well-being or general health-related quality of life.
Further reading & references
- Management of diabetes; Scottish Intercollegiate Guidelines Network - SIGN (March 2010)
- Russell-Minda E, Jutai J, Speechley M, et al; Health technologies for monitoring and managing diabetes: a systematic review. J Diabetes Sci Technol. 2009 Nov 1;3(6):1460-71.
- Hernandez-Tejada MA, Campbell JA, Walker RJ, et al; Diabetes empowerment, medication adherence and self-care behaviors in adults with type 2 diabetes. Diabetes Technol Ther. 2012 Jul;14(7):630-4. doi: 10.1089/dia.2011.0287. Epub 2012 Apr 23.
- Blevins T; Value and utility of self-monitoring of blood glucose in non-insulin-treated patients with type 2 diabetes mellitus. Postgrad Med. 2013 May;125(3):191-204. doi: 10.3810/pgm.2013.05.2668.
- British National Formulary
- Monitoring your diabetes; Diabetes UK
- Diabetic Ketoacidosis (DKA); Diabetes UK
- Kim HS, Shin JA, Chang JS, et al; Continuous glucose monitoring: current clinical use. Diabetes Metab Res Rev. 2012 Dec;28 Suppl 2:73-8. doi: 10.1002/dmrr.2346.
- Langendam M, Luijf YM, Hooft L, et al; Continuous glucose monitoring systems for type 1 diabetes mellitus. Cochrane Database Syst Rev. 2012 Jan 18;1:CD008101. doi: 10.1002/14651858.CD008101.pub2.
- Diagnosis and management of type 1 diabetes in children, young people and adults; NICE Clinical Guideline (July 2004)
- Type 2 diabetes. The management of type 2 diabetes; NICE (May 2009 last modified: March 2014)
- Clar C, Barnard K, Cummins E, et al; Self-monitoring of blood glucose in type 2 diabetes: systematic review. Health Technol Assess. 2010 Mar;14(12):1-140. doi: 10.3310/hta14120.
- Malanda UL, Welschen LM, Riphagen II, et al; Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin. Cochrane Database Syst Rev. 2012 Jan 18;1:CD005060. doi: 10.1002/14651858.CD005060.pub3.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Colin Tidy
Dr Colin Tidy
Dr Jacqueline Payne