Synopsis
Select and monitor established type 2 diabetes medicines by mechanism, kidney function, hypoglycaemia, heart failure, weight and adverse-effect risk.
- Metformin reduces hepatic glucose production, is weight neutral or modestly weight reducing, and rarely causes hypoglycaemia alone; gastrointestinal intolerance and kidney function limit use.
- Start metformin gradually with food and consider modified-release formulation when gastrointestinal effects prevent adherence; review renal thresholds against current BNF and NICE guidance.
- Metformin commonly lowers vitamin B12 over time, so investigate anaemia, neuropathy, glossitis or cognitive symptoms and consider periodic testing in those at risk.
Key red flags
Acute kidney injury, severe dehydration, tissue hypoxia, sepsis or hepatic failure reduces lactate clearance and should trigger temporary withdrawal and urgent physiological assessment.
Investigation priorities
Measure effect and detect excessive or inadequate treatment.
Management branches
Metformin selected within the current NICE phenotype-based regimen.
- Confirm kidney function, acute illness, alcohol exposure, tissue-hypoxia risk and pregnancy context; explain gastrointestinal effects and sick-day interruption before the first prescription.
- Start low with food and increase gradually using immediate or modified release according to tolerance and the current formulary, rather than beginning at the maximum dose.
Key medicines
Metformin immediate or modified releaseStart at a low dose with food and titrate using current renal guidance.
GliclazideBegin conservatively and titrate to glucose response under the local formulary.