Metformin
First-line oral therapy for type 2 diabetes worldwide. WHO Essential Medicines, ADA and EASD guideline anchor since 1957.
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WHAT IS METFORMIN?
Detailed overview
Metformin is a biguanide-class oral antidiabetic whose primary action is suppression of hepatic gluconeogenesis via activation of AMP-activated protein kinase (AMPK). Currently the safest and cheapest licensed T2DM agent, with demonstrated cardiovascular outcome benefit in overweight diabetics since UKPDS-34 (1998, Lancet). The ADA/EASD 2022 consensus places Metformin as initial therapy for all T2DM patients without ASCVD, heart failure or CKD-priority (where SGLT2i or GLP-1 RA take precedence). Off-label indications: prediabetes (DPP 2002 NEJM), PCOS anovulation, gestational diabetes, mitigation of antipsychotic-induced weight gain.
ATC code
A10BA02
Prescription
Prescription only (Rx)
Mechanism
AMPK activator, hepatic gluconeogenesis inhibitor
Half-life
4-9 h (plasma), 17 h (erythrocyte)
Onset
1-3 h (single dose), 4-7 days (steady-state HbA1c)
Metabolic support
Glucose and lipid metabolism shift favorably: insulin sensitivity improves, glycemic swings and HbA1c drop, while LDL and triglycerides normalize. Body composition refines, fat mass decreases, lean mass is preserved or grows. Appetite is regulated both centrally and peripherally (GLP-1 / GIP / glucagon pathways), so caloric intake settles into a sustainable range without constant willpower. Energy expenditure and thermogenesis rise modestly.
Data console
Lab data
Research indications
Investigated uses and mechanisms
Weight regulation
Reduced appetite and increased energy expenditure via GLP-1 / GIP / glucagon agonism.
Type 2 diabetes
Improved insulin sensitivity and HbA1c reduction in clinical trials.
Cardiometabolic profile
Favorable shifts in lipid profile and blood pressure.
Safety
Side effects, stop signs, contraindications
Side effects · 5
- Lactic acidosis (rare but life-threatening, FDA boxed warning): muscle weakness, abdominal pain, rapid breathing, hypothermia; risk increased with renal impairment, dehydration, alcohol or hypoxia.
- Gastrointestinal effects (20-30%): nausea, diarrhea, abdominal discomfort, bloating; reduced by taking with food, slow titration, or an extended-release formulation.
- Reduced vitamin B12 absorption with long-term use, which may cause anemia and peripheral neuropathy; annual B12 monitoring is recommended.
- Metallic taste, decreased appetite (usually transient, in the first weeks of treatment).
- Hypoglycemia: minimal in monotherapy, but increased risk when combined with insulin or sulfonylureas (tremor, sweating, confusion).
Contraindications · 5
- Severe renal impairment (eGFR < 30 ml/min/1.73 m²)
- Acute metabolic acidosis (diabetic ketoacidosis, lactic acidosis history)
- Acute severe heart failure, hypoxic states, shock
- Severe hepatic impairment
- Hold for 48 h around iodinated contrast imaging
Related Pharmaceuticals
Same therapeutic category
Studies
Related research and clinical findings
Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34)
UK Prospective Diabetes Study (UKPDS) Group.
Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin (DPP)
Diabetes Prevention Program Research Group.
Evidence that metformin exerts its anti-diabetic effects through inhibition of complex 1 of the mitochondrial respiratory chain
Owen MR, Doran E, Halestrap AP.
Role of AMP-activated protein kinase in mechanism of metformin action
Zhou G, Myers R, Li Y et al.
Management of hyperglycaemia in type 2 diabetes, 2022. A consensus report by ADA and EASD
Davies MJ, Aroda VR, Collins BS et al.
Metformin use in pregnancy: promises and concerns
Lindsay RS, Loeken MR.
Long-term metformin use and vitamin B12 deficiency in the Diabetes Prevention Program Outcomes Study
Aroda VR, Edelstein SL, Goldberg RB et al.
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Have a question about Metformin?
Educational drug info from official sources (PubMed, FDA, EMA). Does NOT replace medical consultation or the SmPC. Talk to your doctor!
The information here is for educational and scientific purposes only. Medication use requires medical consultation and a prescription. The indications, dose ranges, and side effects listed here do NOT replace the official Summary of Product Characteristics (SmPC) or consultation with a physician. Do not start or stop any medication on your own. In an emergency, call your local emergency number.