Metformin
Also known as: Glucophage, Glucophage XR
Biguanide | AMPK Activator & Longevity Research
Overview
Metformin is a biguanide compound and the most widely prescribed oral medication for type 2 diabetes mellitus worldwide, with over 150 million prescriptions annually. Originally derived from the French lilac (Galega officinalis), metformin was introduced in clinical practice in the 1950s in Europe and received FDA approval in the United States in 1995. Beyond its well-established role in glucose regulation, metformin has attracted significant attention in longevity and aging research. The Targeting Aging with Metformin (TAME) trial, a landmark multi-center study, is investigating whether metformin can delay the onset of age-related diseases in non-diabetic older adults. Observational data have suggested that diabetic patients taking metformin may have lower all-cause mortality than age-matched non-diabetic controls, prompting serious scientific interest in its potential geroprotective properties.
Key benefits
- Improved insulin sensitivity and glucose regulation
- Activation of AMPK, the master metabolic energy sensor
- Potential lifespan extension and delay of age-related diseases (under investigation in TAME trial)
- Reduced hepatic glucose output (gluconeogenesis suppression)
- Modest weight loss or weight neutrality compared to other diabetes medications
- Anti-inflammatory effects through NF-kB pathway suppression
- Potential anti-cancer properties via mTOR inhibition and AMPK activation
- Improved lipid profile with modest reductions in LDL cholesterol and triglycerides
Mechanism of action
Metformin exerts its primary effects through activation of AMP-activated protein kinase (AMPK), the cell's master energy sensor. AMPK activation triggers a cascade of downstream metabolic improvements: enhanced glucose uptake in skeletal muscle, suppression of hepatic gluconeogenesis, improved mitochondrial function, and increased fatty acid oxidation. Metformin also inhibits Complex I of the mitochondrial electron transport chain, which contributes to its AMPK-activating effects by increasing the AMP-to-ATP ratio. Beyond glucose metabolism, metformin modulates several pathways implicated in aging, including inhibition of mTOR signaling (a key regulator of cellular growth and senescence), reduction of oxidative stress and reactive oxygen species, attenuation of chronic low-grade inflammation via NF-kB pathway suppression, and activation of autophagy. These pleiotropic mechanisms underpin both its antidiabetic efficacy and its potential as an anti-aging compound.
Molecular data
- Type
- Biguanide (C4H11N5)
- Half-life
- ~5 hours
Indications
What the research community uses this compound for, with self-reported effectiveness.
Metabolic Health
Longevity / Anti-Aging
Body Composition
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Delivery method
| Protocol | Dose | Frequency | Duration |
|---|---|---|---|
| — | 500 mg, titrate to 1500-2000 mg/day | Start 500 mg once or twice daily, increase by 500 mg weekly | — |
| — | 500-1000 mg/day | Once or twice daily | — |
| — | 500-1500 mg/day | Once or twice daily | — |
| — | 1500-2000 mg/day | Divided 2-3 times daily or once daily (XR) | — |
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Gastrointestinal distress (nausea, diarrhea, bloating, abdominal cramping) - most frequent complaint, affects up to 25% of users
- Metallic taste in mouth
- Decreased appetite
- Flatulence and abdominal distension
- Loose stools, particularly when initiating therapy or increasing dose
Rare side effects
- Vitamin B12 deficiency (occurs in 5-10% of long-term users, can lead to megaloblastic anemia and peripheral neuropathy if undetected)
- Lactic acidosis (extremely rare but potentially fatal, incidence approximately 3-10 per 100,000 patient-years, almost exclusively in patients with contraindicated renal or hepatic impairment)
- Hypoglycemia (only when combined with sulfonylureas or insulin, not with metformin monotherapy)
Contraindications
- Severe renal impairment (eGFR below 30 mL/min/1.73m2)
- Acute or chronic metabolic acidosis, including diabetic ketoacidosis
- Known hypersensitivity to metformin
- Acute conditions with potential for tissue hypoxia (decompensated heart failure, respiratory failure, recent MI, sepsis)
- Severe hepatic impairment
- Excessive alcohol intake (increases risk of lactic acidosis)
Monitoring
- Renal function (eGFR): at baseline, then at least annually; more frequently in patients with declining renal function
- Vitamin B12 levels: at baseline and annually with long-term use (supplement if deficient)
- HbA1c: every 3-6 months until stable, then every 6-12 months
- Complete blood count: annually to monitor for B12 deficiency-related anemia
- Hepatic function: at baseline; periodic monitoring if clinically indicated
- Lactate levels: only if symptoms suggestive of lactic acidosis arise (not routine)
References
Primary literature and clinical-trial data informing this entry.