Self-monitoring in Diabetes Mellitus

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Diabetes mellitus management involves lowering blood glucose, blood pressure, and cholesterol levels to as near normal as possible (as well as encouraging a healthy diet and exercise) to minimise disease complications. Most diabetics will have regular HbA1c measurement by their GP (1-4 times a year) which gives a reasonable estimation of control in most cases except where there are frequent hypoglycaemic events. 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 during a full informed discussion with the patient. An important principle is that monitoring is only useful if it is used to inform decisions (eg adjusting tablets or insulin dosage).

Various methods of glucose monitoring are available, from the least invasive HbA1c measurement to self-monitoring of urine or blood glucose at an appropriate frequency. If 3-6 monthly HBA1c provides enough information (eg in a well controlled type 2 diabetic on oral hypoglycaemics) there is no need for more intensive testing. Conversely, if a patient on insulin has the knowledge and motivation to adjust doses according to the blood glucose values then self-monitoring blood glucose (SMBG) up to 4-6 times daily may be appropriate.[1]

Diabetics 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 seek medical advice if ketones are present.

This provides people with diabetes mellitus with an accurate method of measuring blood glucose concentrations and therefore detecting both hyperglycaemia or hypoglycaemia. There is currently a great deal of debate about the need and frequency of blood glucose monitoring in diabetes mellitus. The debate is focused on the balance between the high and rising NHS expenditure on blood glucose monitoring and the importance of the involvement and empowerment of people with diabetes in their own care.[1] 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.

Diabetics on insulin

Scottish Intercollegiate Guidelines Network (SIGN) guidance recommends:[2]
  • Self-monitoring of blood glucose for patients (both type 1 or type 2) who are using insulin where they have been educated in how to alter their insulin doses.
  • It is not routinely recommended in other type 2 diabetics, but may be considered in type 2 diabetics not on insulin:
    • During an acute illness.
    • If there is an increased risk of hypoglycaemia.
    • Where there is a significant change of drug therapy, or fasting (eg during Ramadan).
    • If there is unstable or poor hypoglycaemic control (HbA1c >8.0% = 64 mmol/mol).
    • If pregnant or planning a pregnancy.

Role of blood glucose testing

  • Strict control of blood glucose levels improves the outcomes in patients with either type I or type 2 diabetes. However, it is not clear whether self-monitoring contributes to this improvement.
  • For self-monitoring blood glucose (SMBG) to be most useful, it should form part of a wider programme of management.
  • Self-monitoring is most appropriate for patients with type I diabetes or type 2 diabetes who use insulin regimes and adjust their dose as a result of blood glucose testing, and for all diabetic patients when they have intercurrent illness.
  • The need and extent of home glucose testing will depend on the treatment required for diabetes, the degree of glycaemic control and the preferences and needs of each individual.[3]

The more recent National Institute for Health and Clinical Excellence (NICE) guideline clarifies the situation 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. See below.

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  • Patients should be given adequate training in self-monitoring techniques, including interpretation of results and appropriate action when required. Many people with diabetes provide books full of results but still don't fully understand the implications of the results or have a full understanding of diabetes mellitus and its implications and management.
  • Glucose testing meters should be checked and recalibrated at recommended intervals to ensure accuracy.

Patients using insulin[1]

  • Patients who are using insulin but have good glycaemic control still need to perform blood tests regularly.
  • The regime should be appropriate and acceptable to each individual patient.
  • Those using basal-bolus or twice-daily insulin therapy should be educated to undertake self-monitoring blood glucose (SMBG) at least once daily, varying the time between fasting, pre-meal and post-meal, to help build up a profile of glycaemic control throughout the day. Some patients prefer to perform frequent tests on 2 or 3 days in the week and then again only if concerned about possible hypoglycaemia.
  • Frequent self-monitoring is required during illness (at least four times a day).
  • Ideally, patients who are on a multiple daily insulin regime (ie if they alter doses at mealtimes) should self-monitor their blood glucose up to 4 times daily.
  • Patients with symptoms of nocturnal hypoglycaemia or resistant morning hyperglycaemia should measure blood glucose levels in the early hours of the morning (between 2 am and 3 am).
  • Patients who are pregnant or hoping to become pregnant, or using insulin pump therapy should monitor their blood glucose levels between 4-6 times daily.
  • Patients with type 2 diabetes on insulin with oral hypoglycaemic agents should be encouraged to self-monitor at least once daily, varying the time between fasting, pre-meal and post-meal, to identify trends. Fasting blood glucose should be tested daily during basal insulin dose titrations.
  • Diabetics with unstable HbA1c or SMBG levels should be encouraged to test more frequently to inform any treatment decisions.

People with type 2 diabetes who are not using insulin

  • There is no evidence that blood testing is more effective than urine testing at improving blood glucose control in people with type 2 diabetes.
  • Many people with type 2 diabetes, especially those who are diet-controlled, do not need to perform home blood glucose monitoring. There is no risk of hypoglycaemia, and glycaemic control is better and adequately monitored by regular testing of glycosylated haemoglobin.
  • Patients with type 2 diabetes who are taking a sulphonylurea are at risk of hypoglycaemia and so have a greater need to SMBG.
  • It is not known what the ideal frequency of self-monitoring should be in type 2 diabetes. Current recommendations are based on consensus opinion.

When compared with blood glucose monitoring, urinalysis for measurement of urinary glucose is a very imprecise method for monitoring glucose control in diabetes mellitus.

  • There is only limited evidence that glucose monitoring improves outcomes in patients with type 2 diabetes.[5] However there is no evidence that blood glucose testing is more effective than urine testing in improving blood glucose control in people with type 2 diabetes.
  • Urine monitoring may be used as an alternative to blood glucose monitoring for some patients with type 2 diabetes who are managed by either diet alone or with oral hypoglycaemic drugs (eg those patients who are unable or unwilling to measure capillary blood glucose levels), in association with regular HbA1c blood checks.
  • Urine glucose testing should not be used instead of glucose monitoring for people with type 1 diabetes.

Advantages

  • Urine testing is easy to perform and does not require a meter with associated maintenance and battery replacement needs.
  • Urine testing is cheaper.
  • It does not require lancets with the associated safety and disposal issues.

Disadvantages of urine glucose monitoring

  • A negative test does not distinguish between normoglycaemia and hypoglycaemia.[6]
  • The renal threshold for glucose is approximately 10 mmol/L but varies in individuals between 8 and 12 mmol/L. The threshold is lower in children and pregnant women, who are therefore more likely to have false positive results, and higher in the elderly and those with renal impairment, who are therefore more likely to have false negative results. Fluid intake may also affect glycosuria.
  • The level of glycosuria represents an average of blood glucose levels since the patient last passed urine. Collecting a sample soon after emptying the bladder helps to reduce this problem.

Further reading & references

  1. Care recommendations: Self-monitoring of blood glucose, Diabetes UK
  2. Management of diabetes; Scottish Intercollegiate Guidelines Network - SIGN (March 2010)
  3. Health Technology Assessment; Monitoring blood glucose control in diabetes mellitus: a systematic review. October 2003; Volume 4, number 12
  4. Type 2 diabetes - newer agents (partial update); NICE Clinical Guideline (May 2009)
  5. Franciosi M, Pellegrini F, De Berardis G, et al; The impact of blood glucose self-monitoring on metabolic control and quality of life in type 2 diabetic patients: an urgent need for better educational strategies. Diabetes Care. 2001 Nov;24(11):1870-7.
  6. The Role Of Urine Glucose Monitoring In Diabetes, International Diabetes Federation, March 2005

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.

Original Author:
Dr Colin Tidy
Current Version:
Last Checked:
20/04/2011
Document ID:
455 (v7)
© EMIS