Systematic review: GLP-1 analogs improve glycemic control in type 2 diabetes

A pancreas

Glucagon-like peptide (GLP-1) analogues, such as exenatide and liraglutide, are drugs that promote the action of insulin in the body and help people with type 2 diabetes control their blood sugar levels.

This new systematic review collates all of the evidence about the effectiveness of this type of drug compared with other possible treatments.  This evidence may inform the choice from the range of many different treatments for type 2 diabetes.

The reviewers report:

  • Compared with placebo, GLP-1 agonists reduced glycosylated haemoglobin A1c (HbA1c) levels by about 1%.
  • GLP-1 analogs also performed better than insulin glargine, sitagliptin and pioglitazone.

However, the evidence is complex among comparisons between the various competing possible treatments and much of the evidence was inconclusive.

Furthermore, the reviewers report that all of the studies they found were rather short – 26 weeks or less.  Longer term follow-up is needed to confirm efficacy and harm data.

Appraisal hints

Users of this evidence are advised to:

  • Look for evidence relating to combination with other interventions.
  • Look for a robust assessment of the quality of individual studies.
  • Look for the statistical significance of findings, preferable relating to objectives outcomes, such as proportion of patients achieving good control, rather than just the average improvement in HbA1c.
  • Consider the potential impact of heterogeneity between studies.
  • This evidence should be considered in context with clinical guidelines for drug treatment of type 2 diabetes, including updates for new oral agents.
  • Consider individual values and preferences.
  • Consider the impact of adverse events such as hypoglycemia and nausea.


The full text is available from The Cochrane Library:

Shyangdan DS, Royle P, Clar C, Sharma P, Waugh N, Snaith A.  Glucagon-like peptide analogues for type 2 diabetes mellitus. Cochrane Database Syst Rev. 2011;10:CD006423


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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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