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Table 5 Recommendations to stop the use of metformin in older people with type 2 Diabetes mellitus

From: Efficacy and safety of metformin in the management of type 2 diabetes mellitus in older adults: a systematic review for the development of recommendations to reduce potentially inappropriate prescribing

Recommendations Strength of the recommendation Quality of the evidence Type of evidence
It is suggested to discontinue metformin for the management of type 2 diabetes mellitus in patients with 2 or more of the following risk factors: age > 80; gastrointestinal complaints during the last year; GFR ≤60 ml/min. The benefit of metformin in this patient is uncertain and it is possibly outweighed by the risk of adverse drug reactions, depending on their severity. Weak Low Observational study [42]; RCTs [36, 43]; clinical guideline [46]
Reason: uncertainty about the magnitude of the benefits and harms. It was considered to downgrade the quality of the evidence to low quality because there were study limitations (1 observational study with limitations and 2 RCTs with unclear risk of bias), indirectness (observational study with subgroup analysis), inconsistency (different types of comparisons evaluated).
It is suggested to discontinue metformin for the management of type 2 diabetes mellitus in patients 80 years and older taking the life expectancy, physical and functional status of the patient into account. Patients who are concerned about adverse events or appear to experience AE may reasonably choose not to take metformin. Weak Low Observational study [42]
Reason: uncertainty about the magnitude of the benefits and harms. It was considered to keep the quality of the evidence as low quality because this observational study had limitations: data in older people was from subgroup analysis, lack of reporting on recruitment and confounding factors.
It is suggested to discontinue metformin for the management of type 2 diabetes mellitus in patients with gastrointestinal complaints taking the possible benefit and the severity of the patient complaints as possible dverse drug reactions into account. Weak Low RCTs [36, 43]
Reason: small RCTs with low quality and no significant benefits with metformin; uncertainty about the magnitude of the benefits and harms. It was considered to downgrade the quality of the evidence to low quality because there were study limitations (2 RCTs with unclear risk of bias) and inconsistency (different types of comparisons evaluated).
It is suggested to discontinue metformin for the management of type 2 diabetes mellitus in patients with renal insufficiency because metformin may increase the risk of lactic acidosis. Weak Low Clinical guideline [46]
Reason: evidence from a clinical guideline; uncertainty about the magnitude of the benefits and harms. It was considered to keep the quality of the evidence as low quality because it was from a clinical guideline.