Comparison
Magnesium L-Threonate vs Metformin
Side-by-side of Magnesium L-Threonate and Metformin. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Magnesium L-Threonate
Magnesium l-threonate (Magtein) crosses the blood-brain barrier. Typical dose 1,500-2,000 mg. Sleep and cognitive trial data, side effects.
Metformin
Metformin for longevity: biguanide mechanism of action, TAME trial status, anti-aging dosage, weight loss data, life extension evidence in non-diabetics.
Effects at a glance
Magnesium L-Threonate
- •Distinct magnesium salt designed for blood-brain barrier penetration; not a higher-quality systemic magnesium
- •Liu 2010 rodent study: elevated CSF magnesium ~15% and increased hippocampal synaptic density
- •Trial portfolio in humans is small and mostly Magtein-funded; cognitive effects are modest where reported
- •Typical dose 1500 to 2000 mg/day delivers only ~108 to 144 mg of elemental magnesium
- •GI tolerability comparable to other magnesium forms; loose stools in a minority at 2000 mg/day
- •Distinct from magnesium glycinate, which is the conventional sleep/anxiety/repletion form
Metformin
- •Reduces HbA1c by ~1.0 to 1.5 percentage points in type 2 diabetes; first-line agent in major guidelines
- •DPP trial: 31% reduction in T2DM incidence in adults with prediabetes over 2.8 years
- •Suppresses hepatic gluconeogenesis via AMPK activation and complex I inhibition
- •Long-term use depletes B12; annual monitoring recommended after year 2
- •Lifespan extension in non-diabetic humans is not established; TAME trial pending
- •MASTERS trial reported blunted resistance-training hypertrophy in older adults
Side-by-side
| Attribute | Magnesium L-Threonate | Metformin |
|---|---|---|
| Category | supplement | pharmaceutical |
| Also known as | Mg-T, MgT, Magtein, magnesium threonate | Glucophage, Fortamet, Glumetza, dimethylbiguanide |
| Half-life (hr) ↗ | 4 | 6 |
| Typical dose (mg) ↗ | 2000 | 1500 |
| Dosing frequency | 1 to 3 times daily | 1 to 3 times daily with meals; XR once daily |
| Routes | oral | oral |
| Onset (hr) | 1 | 1 |
| Peak (hr) | 2 | 2.5 |
| Molecular weight | 294.5 | 129.16 |
| Molecular formula | C8H14MgO10 | C4H11N5 |
| Mechanism | Proposed to deliver magnesium across the blood-brain barrier more effectively than other oral salts via threonate-related transporters, raising CNS magnesium and modulating NMDA receptor function and synaptic plasticity. | Suppresses hepatic gluconeogenesis primarily via AMPK activation and complex I inhibition; modestly improves peripheral insulin sensitivity and shifts gut microbiome composition. |
| Legal status | OTC dietary supplement | Prescription only (FDA approved for type 2 diabetes 1994) |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement (not scheduled) | Rx only (not a controlled substance) |
| Pregnancy | Standard magnesium safety; Mg-T-specific data limited | Category B; used in gestational diabetes and PCOS per current guidance |
| CAS | 778571-57-6 | 657-24-9 |
| PubChem CID | 10691810 | 4091 |
| Wikidata | Q27151568 | Q19484 |
Safety profile
Magnesium L-Threonate
Common side effects
- loose stools
- mild GI upset
- headache (rare)
- fatigue (rare)
Contraindications
- severe renal impairment (eGFR below 30)
- hypermagnesemia
- myasthenia gravis (high doses)
- concurrent IV magnesium therapy
Interactions
- tetracyclines and fluoroquinolones: magnesium chelation reduces antibiotic absorption; separate by 2 to 4 hours(moderate)
- bisphosphonates: reduced absorption; separate by 2 hours minimum(moderate)
- muscle relaxants and aminoglycosides: potentiated neuromuscular blockade at high doses(moderate)
- antihypertensives: additive blood pressure reduction at high doses(minor)
Metformin
Common side effects
- nausea
- diarrhea
- abdominal discomfort
- metallic taste
- decreased appetite
- B12 depletion (long-term)
Contraindications
- eGFR below 30 mL/min/1.73m2
- acute or chronic metabolic acidosis
- severe hepatic impairment
- acute heart failure
- iodinated contrast within 48 hours
Interactions
- iodinated contrast media: renal injury risk; hold 48 hours peri-imaging(major)
- alcohol (heavy use): elevated lactic acidosis risk(major)
- cimetidine: raises metformin plasma levels via OCT2 inhibition(moderate)
- insulin and sulfonylureas: additive hypoglycemia risk in combination(moderate)
- dolutegravir: raises metformin exposure via OCT2(moderate)
Which Should You Take?
Magnesium L-Threonate comes out ahead for most readers on the criteria we weight: 2 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-B outcome catalogued. Metformin is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Magnesium L-Threonate.
- → If your priority is sleep onset or sleep quality, pick Magnesium L-Threonate.
- → If your priority is metabolic health and glucose control, pick Metformin.
- → If your priority is healthspan extension, pick Metformin.
Edge case: If you want to avoid prescription-only, Magnesium L-Threonate is the more accessible choice.
Default choice: Magnesium L-Threonate. Lower friction to source, and broader goal coverage. Reach for Metformin only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Magnesium L-Threonate and Metformin?
Magnesium L-Threonate and Metformin differ in category (supplement vs pharmaceutical), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Magnesium L-Threonate or Metformin?
Magnesium L-Threonate half-life is 4 hours; Metformin half-life is 6 hours.
Can you stack Magnesium L-Threonate with Metformin?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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