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Blood sugar testing in diabetes

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Self-monitoring of blood glucose is common practice. However, there is little evidence to support its use in all people with diabetes - especially type II diabetics - unless there is an effective programme of management in place for the patient (1)

  • in the DiGEM study, blood glucose self-testing or self-monitoring did not improve glycaemic control in patients with type 2 diabetes not treated with insulin (2)

Self-monitoring is likely to be most appropriate for patients with type I or II diabetes, who use insulin and adjust their dose as a result of the test, or for all patients with diabetes when they have an intercurrent illness (1). A MeReC extra publication stated that "routine self-monitoring of blood glucose is unlikely to be beneficial in patients with type 2 diabetes who are not treated with insulin" (3).

The measurement of blood glucose allows reliable detection of both hypo and hyperglycaemia and if instructions are followed with care provides an accurate measure of plasma glucose concentration.

Blood tests should be carried out on a regular basis. Often type I diabetics might be monitoring their blood sugar in a similar schedule to that outlined below:

  • In patient with good glycaemic control testing should be carried out before retiring to bed and on one other occasion each day. The timing of this latter test should be taken at different times on different days.
  • In patients who are unwell, suffering recurrent hypo or hyperglycaemia, or who are trying to improve suboptimal glycaemic control tests should be taken four times daily with an additional test in the early hours of the morning (0200 to 0300hrs).
  • Patients with symptoms of nocturnal hypoglycaemia or resistant hyperglycaemia in the mornings should measure blood glucose in the early hours of the morning (0200 to 0300hrs).

Self-monitoring in type 2 diabetes:

It is not know what the ideal frequency of self-monitoring should be in type II diabetes (1).

NICE state that (4):

  • take the Driver and Vehicle Licensing Agency (DVLA) At a glance guide to the current medical standards of fitness to drive into account when offering self-monitoring of blood glucose levels for adults with type 2 diabetes

  • self-monitoring of plasma glucose should be available:
    • to those on insulin treatment or
    • to those on oral glucose-lowering medications to provide information on hypoglycaemia or
    • the person is on oral medication that may increase their risk of hypoglycaemia while driving or operating machinery or
    • the person is pregnant, or is planning to become pregnant

  • consider short-term self-monitoring of blood glucose levels in adults with type 2 diabetes (and review treatment as necessary):
    • when starting treatment with oral or intravenous corticosteroids or
    • to confirm suspected hypoglycaemia

  • be aware that adults with type 2 diabetes who have acute intercurrent illness are at risk of worsening hyperglycaemia. Review treatment as necessary

  • self-monitoring should be assessed 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
    • equipment used

A Cochrane review found that (5):

  • the overall effect of self-monitoring blood glucose (SMBG) on glycaemic control in patients with type 2 diabetes (who were not using insulin) was small up to six months after initiation, and subsided after 12 months
    • SMBG reduced HbA1c by a statistically significant 0.3% (about 3mmol/mol) at up to six months follow-up, but the reduction was not statistically significant at 12 months.
    • there was no evidence that SMBG affected patient satisfaction, general well-being or general health-related quality of life.


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