Limited evidence of better glycaemic control with GLP-1 analogues in type 2 diabetes

A syringe

We recently reported on a review of GLP-1 analogues as a second line of treatment in type 2 diabetes.  A new systematic review reports on a direct comparison with insulin therapy in poorly controlled type 2 diabetes.

Clinical question:

In type 2 diabetes poorly controlled on oral therapy, do GLP-1 analogues as compared with insulin, improve glycaemic control or reduce complications?

The evidence:

The reviewers found 7 randomised trials, involving 2,199 participants, that compared GLP-1 analogues with insulin.  When they pooled the data from these studies they found:

  • no significant difference between the two in terms of overall glycaemic control (HbA1c).
  • more weight gain in the patients treated with insulin.
  • a 35% reduction in the risk of hypoglycaemia in the patients treated with GLP-1 analogues.

Appraisal hints:

Users of this research should consider:

  • It is almost certain that the reviewers missed important research by only searching the PubMed database.
  • Did they do enough to evaluate the quality of the trials?
  • Does it make sense to combine their results?  Were the patients, treatment regimens and outcome measures used in the different trials sufficiently similar to warrant meta-analysis?
  • How much uncertainty there is around the estimates of benefit for rare outcomes such as hypoglyaemia.  The sample size of the meta-analysis was rather small.
  • The possible safety issues associated with GLP-1 analogues.


Abdul-Ghani MA, Williams K, Kanat M, Altuntas Y, Defronzo RA. Insulin Versus GLP-1 Analogues in Poorly Controlled Type 2 Diabetic Subjects on Oral Therapy A Meta Analysis. J Endocrinol Invest. 2012 Apr 18. [Epub ahead of print]

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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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