| Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
| Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
| Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
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Canadian Diabetes Association 2013 Clinical Practice Guidelines for the Prevention and Management of Diabetes
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Metformin (renal impairment): The National Institute for Health and Care Excellence. Type 2 diabetes in adults: management Clinical Guideline, 2 December 2015. https://www.nice.org.uk/guidance/ng28
Metformin (renal impairment): Aronoff, Bennett et al. Drug Prescribing in Renal Failure: Dosing Guidelines for
Adults and Children, 5th Edition. American College of Physicians.United States of America, 2007.
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Metformin (renal impairment): South African Medicines Formulary. 12th Edition. Division of Clinical Pharmacology.University of Cape Town. 2016.