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Metformin as firstline treatment for type 2 diabetes: are we sure?

BMJ 2016; 352 doi: https://doi.org/10.1136/bmj.h6748 (Published 08 January 2016) Cite this as: BMJ 2016;352:h6748

Rapid Response:

Re: Metformin as firstline treatment for type 2 diabetes: are we sure?

Boussageon and colleagues state that the UKPDS result with metformin has never been reproduced. The problem with that statement is that no such long study going on for well over 10 years has been undertaken to compare with the UKPDS and so the statement is misleading. The graphs published in the UKPDS 10 year follow up report, mentioned by Boussageon and colleagues, show that it is 3 years before these graphs, that demonstrate the reduced deaths and reduced myocardial infarctions with metformin, start to separate from those of the conventional therapy. This shows that short-term studies cannot be relied upon to give us the information we require.

Boussageon and colleagues ask for studies involving between 5,000 and 10,000 participants. There is often an implication that it is a weakness of the UKPDS result that it was found with the study involving only 342 patients in the metformin group and 411 in the conventional group. In fact it is a testimony to the strength of the metformin effect that it could be demonstrated in such a relatively small number of patients. Supposing it was 1922 and there were 20 patients about to die from type 1 diabetes. Supposing 10 were given the newly discovered insulin and 10 had “conventional” treatment. Supposing the 10 who had insulin survived and flourished, while the 10 who had “conventional” treatment died. Would we then go on to request a study involving 5,000 or 10,000 patients in order to believe that insulin stops people with type 1 diabetes from dying?

The case put by Boussageon and colleagues is insufficient to stop us using metformin as first line therapy in obese patients with type 2 diabetes.

Competing interests: No competing interests

19 February 2016
Robert E Ryder
Consultant Physician with an interest in diabetes and endocrinology
Sandwell and West Birmingham Hospitals NHS Trust
Birmingham B18 7QH, UK