In type 2 diabetes not on insulin, SMBG does not significantly reduce HbA1c

Self testing of blood glucose

This meta-analysis of individual patient data looked at whether self-monitoring of blood glucose improved glycaemic control in people with type 2 diabetes not on insulin.

Clinical question:

In type 2 diabetes not on insulin, does SMBG as compared to usual care, improve glycaemic control?

The review also looked for improvements in blood pressure and cholesterol.

The evidence

Six randomised trials were found that met the inclusion criteria.  Individual data from the 2,552 participants in these trials were pooled in a meta-analysis.

The reviewers concluded that although SMBG resulted in a reduction in HbA1c of 2.7 mmol/mol (95% CI 3.9 to 1.6 mmol/mol), or 0.25% at 12 months of follow-up. However, the concluded that this benefit was not clinically significant:

It is widely agreed that for further evaluation of self monitoring of blood glucose, the therapeutic interventions and efforts to promote behavioural change should be more tightly aligned to the results obtained from monitoring, and targeted at those likely to benefit.

There was not enough data to enable the anlysis to pick out any sub-groups of patients who are more likely to benefit, nor to examine the secondary outcomes of blood pressure or cholesterol.

Appraisal hints

Users of this research should consider:

  • SMBG can only work if it is accompanied by appropriate education and intervention by both patients and professionals.  Was there important heterogeneity between the studies in the provision of such support?  For example, educational interventions have improved over time, and we might expect older trials to have a lower standard of provision.
  • Was there blind, independent assessment of the quality of the individual studies?
  • The analysis does not rule out possibile benefits from SMBG when targeted correctly or in particular sub-groups of patients.


The full text of this paper is available from the BMJ website.

Farmer AJ, Perera R et al. Meta-analysis of individual patient data in randomised trials of self monitoring of blood glucose in people with non-insulin treated type 2 diabetes. BMJ 2012;344:e486.


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I am an information scientist with an interest in making knowledge from systematic research more accessible to people who need it. This means you. I've been attempting this in the area of Evidence-Based Health Care since 1995. So far the results have been mixed. For some reason we expected busy clinicians to search databases and appraise papers instead of seeing patients. We also expected publishers to make the research freely available to the people who paid for it.. Ha! Hence The National Elf service.

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