NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated July 13, 2026

Metformin

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

Metformin is the first-line oral medication for type 2 diabetes mellitus. It lowers blood glucose by reducing hepatic glucose production and improving insulin sensitivity in peripheral tissues. It is one of the most widely prescribed diabetes medications worldwide and has an extensive safety profile spanning decades of clinical use.

Evidence tier
Strong
Indexed sources
13 2016–2026
Interactions
0
Depletes
2 nutrients
Read the sources → Compare profiles
Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

Metformin is the first-line oral medication for type 2 diabetes mellitus. NutriStack rates the supporting evidence as strong. Common adult dosing is 500–2,550 mg daily in divided doses (as prescribed by your physician), though a prescriber sets the actual dose. With long-term use it can deplete vitamin b12, folate. This profile indexes 13 sources.

What it's good for
  • Lowers fasting and postprandial blood glucose8,9
  • Reduces HbA1c by 1.0–1.5%
  • Weight neutral or modest weight loss3
  • Cardiovascular risk reduction in overweight patients7,8
  • Low risk of hypoglycemia as monotherapy8
What to watch for
  • Nausea and vomiting
  • Diarrhea
  • Abdominal bloating and cramping
  • Severe renal impairment (eGFR < 30 mL/min/1.73 m²)7
  • Metabolic acidosis including diabetic ketoacidosis

The bottom line

Evidence rating strong. Most-documented uses: lowers fasting and postprandial blood glucose, reduces hba1c by 1.0–1.5%, weight neutral or modest weight loss. 13 sources indexed (2016–2026), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Activates AMP-activated protein kinase (AMPK), which suppresses hepatic gluconeogenesis and increases glucose uptake in skeletal muscle. Also inhibits mitochondrial complex I in hepatocytes, reducing ATP production and shifting the cell toward catabolic pathways. Additionally decreases intestinal absorption of glucose and improves insulin receptor signaling.

Class
Biguanide
Absorption
Water-soluble; take with food
Dosing

Dosing & protocol.

Common range
500–2,550 mg daily in divided doses (as prescribed by your physician)
Recommended form
Extended-release tablet preferred for GI tolerability

Take with meals to reduce gastrointestinal side effects. Extended-release tablets should be swallowed whole.

Depletions

What it depletes.

Nutrients this medication can lower over time, and what to replace.

Vitamin B12

Significant

Metformin impairs calcium-dependent uptake of the intrinsic factor-B12 complex in the terminal ileum, lowering B12 absorption during long-term use.

Replace MethylcobalaminMonitor Serum B12 + methylmalonic acidOnset Most evident after 6-24 months of regular use

Folate

Moderate

Long-term metformin use is associated with lower folate status, likely through impaired intestinal absorption and altered enterohepatic handling.

Replace MethylfolateMonitor Serum folate or RBC folateOnset Usually after several months of regular use

Full Metformin depletion and interaction guide →

Safety

Full safety detail.

Side effects

  • Nausea and vomiting
  • Diarrhea
  • Abdominal bloating and cramping
  • Metallic taste
  • Vitamin B12 deficiency with long-term use
  • Lactic acidosis (rare but serious)

Contraindications

  • Severe renal impairment (eGFR < 30 mL/min/1.73 m²)7
  • Metabolic acidosis including diabetic ketoacidosis
  • Known hypersensitivity to metformin1,2
  • Acute or chronic conditions predisposing to tissue hypoxia (e.g., decompensated heart failure, respiratory failure)
  • Severe hepatic impairment
Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Meta-analyses & systematic reviews

8

Reference material

5
FAQ

Common questions.

Quick answers about Metformin, drawn from the data on this page.

What is Metformin?

Metformin is the first-line oral medication for type 2 diabetes mellitus. It lowers blood glucose by reducing hepatic glucose production and improving insulin sensitivity in peripheral tissues. It is one of the most widely prescribed diabetes medications worldwide and has an extensive safety profile spanning decades of clinical use.

What is Metformin used for?

Commonly cited benefits of Metformin include: Lowers fasting and postprandial blood glucose; Reduces HbA1c by 1.0–1.5%; Weight neutral or modest weight loss; Cardiovascular risk reduction in overweight patients; Low risk of hypoglycemia as monotherapy. NutriStack rates the overall evidence as strong.

What is a typical dose of Metformin?

A typical adult dose of Metformin is 500–2,550 mg daily in divided doses (as prescribed by your physician). The commonly recommended form is Extended-release tablet preferred for GI tolerability. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Metformin?

Reported side effects include nausea and vomiting, diarrhea, abdominal bloating and cramping, metallic taste, vitamin b12 deficiency with long-term use, lactic acidosis (rare but serious). This is educational information; check with a healthcare professional before use.

How strong is the evidence for Metformin?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

Metformin in NutriStack.

Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.

Download on the App Store → Read the methodology

NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.