When metformin is contra-indicated or not tolerated
Type 2 diabetes mellitus: Quality prescribing strategy - a guide for improvement
When metformin is contra-indicated or not tolerated, the following factors should be considered, similar to those for second choices (see Cardiovascular and renal risk for more information).
When assessing an individual, it is good practice to establish whether the individual:
- has any existing atherosclerotic cardiovascular disease (ASCVD)
- has a very high risk of developing ASCVD (aged >55 years and has carotid, coronary or peripheral artery stenosis >50%, or left ventricular hypertrophy (LVH))
- has symptomatic heart failure
- needs to avoid or minimise the risk of hypoglycaemia (e.g. occupation, driving); or
- needs to minimise weight gain
If HbA1c remains above the agreed treatment target for the individual, the following should be considered:
- optimising the dose of the current medication
- adding a drug of a different class
- stopping drugs that were ineffective and did not lead to a measurable improvement in HbA1c; and
- considering drug-specific and individual factors when selecting which anti-hyperglycaemic treatments to use
- reviewing and adjusting every three to six months in discussion with the person living with T2DM
See the table in section 'Summary of the benefits and cautions for anti-diabetic therapies' for anti-diabetic therapies, based on ADA40 and ABCD.41
Prescribers should familiarise themselves with the prescribing indications and contra-indications of individual agents, as these may vary within drug classes as well as interactions listed in the BNF and/or the Electronic Medicines Compendium, before initiating therapies in line with local formularies.