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Please enter at least one feature (symptom, sign or investigation result) before performing the calculation.
For example, if chest pain and low oxygen saturations were present, but haemoptysis was absent, the features section should look as follows:
To add a feature that is present, start typing and then click the green arrow.
To add the absence of a feature (i.e. a 'negative' finding), start typing then click the red cross.
If you want to remove a feature from the list simply click the grey cross in the box to the right of the feature.
Metformin is a biguanide used mainly in the treatment of type 2 diabetes mellitus. It has a number of actions which improves glucose tolerance. Unlike sulphonylureas it does not cause hypoglycaemia and weight gain and is therefore first-line, particularly if the patient is overweight. Metformin is also used in polycystic ovarian syndrome and non-alcoholic fatty liver disease
Mechanism of action
Mechanism of action
Acts by activation of the AMP-activated protein kinase (AMPK)
Increases insulin sensitivity
Decreases hepatic gluconeogenesis
May also reduce gastrointestinal absorption of carbohydrates
Gastrointestinal upsets are common (nausea, anorexia, diarrhoea), intolerable in 20%. If patients develop unacceptable side-effects then modified-release metformin should be considered
Reduced vitamin B12 absorption - rarely a clinical problem
Lactic acidosis with severe liver disease or renal failure
Chronic kidney disease: NICE recommend that the dose should be reviewed if the creatinine is > 130 µmol/l (or eGFR < 45 ml/min) and stopped if the creatinine is > 150 µmol/l (or eGFR < 30 ml/min)
Metformin may cause lactic acidosis if taken during a period where there is tissue hypoxia. Examples include a recent myocardial infarction, sepsis, acute kidney injury and severe dehydration
Iodine-containing x-ray contrast media: examples include peripheral arterial angiography, coronary angiography, intravenous pyelography (IVP); there is an increasing risk of provoking renal impairment due to contrast nephropathy; metformin should be discontinued on the day of the procedure and for 48 hours thereafter