Treatment Guidelines for diabetes Mellitus from 2007 to 2011 have been reviewed and not all of seem to have the same views. So the question goes as to how much to rely on them.

Team@CMHF

Background: Clinical practice guidelines have an important role in guiding choices among the numerous medications available to treat type 2 diabetes mellitus, but little is known about their quality.
Purpose: To assess whether guidelines on oral medications for type 2 diabetes are consistent with a systematic review of the current evidence and whether the consistency of the guidelines depends on the quality of guideline development.
Data Sources: MEDLINE, CINAHL, and guideline-specific databases were searched between July 2007 and August 2011, after the 2007 publication of a peer-reviewed systematic review on oral diabetes medications.
Study Selection: Two reviewers independently screened citations to identify English-language guidelines on oral medications to treat type 2 diabetes that were applied in the United States, United Kingdom, and Canada.
Data Synthesis: Of the 1000 screened citations, 11 guidelines met the inclusion criteria. Seven guidelines agreed with the conclusion that metformin is favored as the first-line agent. Ten guidelines agreed that thiazolidinediones are associated with higher rates of edema and congestive heart failure compared with other oral medications to treat type 2 diabetes. One guideline addressed no evidence-based conclusions, and 5 guidelines agreed with all 7 conclusions. Conclusion: Not all practice guidelines on oral treatment of type 2 diabetes were consistent with available evidence from a systematic review. Guidelines judged to be of higher quality contained more recommendations consistent with evidence-based conclusions. The quality of guideline development processes varied substantially.

Ref: http://www.annals.org/content/156/1_Part_1/27.abstract?aimhp