Glucophage®
Metformin
Version 2025-04 · Last reviewed April 1, 2025 · Methodology
List Price
$30
With Insurance
$4
Supplement Questions
Omega-3 Fatty Acids
Omega-3 may support cardiovascular health in diabetic patients alongside glucose-lowering therapy.
Magnesium
Long-term metformin use may reduce magnesium absorption. Deficiency can worsen insulin resistance — the condition metformin is treating.
Berberine
Berberine and metformin share the AMPK activation mechanism. Taking both together may cause blood glucose to drop more than expected. This combination requires physician supervision.
How It Works
Metformin works primarily by telling the liver to stop releasing glucose between meals. It also improves muscle cells' ability to respond to insulin, reducing the amount needed to clear glucose from the blood.
Why the side effects happen
GI side effects (nausea, diarrhea) are caused by metformin's effect on intestinal motility and gut microbiome changes. Taking with food and using extended-release formulations dramatically reduces this. The rare but serious lactic acidosis occurs only when metformin accumulates — which is why it is contraindicated in severe kidney disease.
When Will I Feel It?
Blood glucose begins falling within the first week. Full HbA1c effect takes 3 months because HbA1c reflects the average of the past 90 days.
GI side effects peak — nausea, loose stools, metallic taste. Take with food. These largely resolve within 2–4 weeks.
Fasting blood glucose starts falling. Some patients notice improvement within 1–2 weeks.
Steady improvement in both fasting and post-meal glucose. Full HbA1c impact still building.
Full HbA1c effect visible. The DiRECT trial showed metformin plus intensive lifestyle can achieve remission in some patients.
Adherence Note
HbA1c tests your average blood glucose over 3 months — one measurement after starting metformin won't show the full picture. Clinical guidelines recommend evaluating full effectiveness after a 3-month lab check, since HbA1c reflects a 90-day blood glucose average.
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Common Side Effects
While taking this medication, you may experience the following common side effects. We've included tips on how to manage them.
Nausea
25%Always take with food; start with low dose
Diarrhea
28%Usually improves after 2-4 weeks; take with meals
Stomach upset / cramping
20%Extended-release version causes less GI trouble
Vomiting
7%Take with largest meal of the day
Metallic taste in mouth
15%Common; usually fades over time
Decreased appetite
10%Can be a benefit for weight management
Vitamin B12 deficiency (long-term)
20-30% with long useSupplement B12; have levels checked annually
Flatulence / bloating
12%Reduce dose temporarily; use extended-release
Weakness / fatigue
6%Check B12 levels if persistent
Headache
5%Usually mild and temporary
Serious Adverse Effects
- • Lactic acidosis (rare but potentially fatal)
- • Vitamin B12 deficiency (long-term)
- • Hypoglycemia (when combined with insulin/sulfonylureas)
- • Kidney problems (stop if eGFR <30)
Drug Interactions
Major Interactions (Avoid)
Moderate Interactions (Caution)
Food Interactions
When to Contact Your Doctor
This medication requires ongoing medical supervision. The following situations warrant a prompt conversation with your prescribing physician — do not wait for your next scheduled appointment.
Contact soon if you notice
- Lactic acidosis (rare but potentially fatal)
- Vitamin B12 deficiency (long-term)
- Hypoglycemia (when combined with insulin/sulfonylureas)
- Kidney problems (stop if eGFR <30)
- Fasting blood glucose rising above 130 mg/dL
Also discuss if you want to
- Review whether this medication is still appropriate for you
- Consider dosage adjustments based on response
- Explore lifestyle or non-drug alternatives
- Understand stopping or tapering options
- Plan monitoring labs and follow-up
In the US, call 911 or go to the nearest emergency room for severe symptoms. Poison Control: 1-800-222-1222.
Special Populations
Safety classifications for specific groups — discuss with your provider before use.
Used in gestational diabetes; discuss with OB.
Low levels in milk; generally acceptable.
Insulin resistance rises significantly after menopause due to the loss of estrogen's protective metabolic effects. Metformin is frequently started during this period. Some of this insulin resistance responds to hormone therapy. Lifestyle changes — especially reducing refined carbohydrates — often address post-menopause metabolic changes more effectively than medication alone.
Approved for type 2 diabetes in children ≥10.
Monitor kidney function; stop if eGFR <30.
Risk of lactic acidosis. Hold for contrast.
FDA Adverse Event Reports
Patient-filed reports from the FDA FAERS database · refreshed daily
Community Reports
User-reported experiences — anonymous & anecdotal
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Metabolic & Lifestyle Alternatives
Dietary & Lifestyle Approaches to Blood Sugar Management
Lifestyle intervention reduced T2D risk by 58% in a landmark NIH-funded trial (Diabetes Prevention Program, 2002)
Important context: Evidence quality varies across these approaches. Some are well-studied with randomized controlled trial data; others are based on observational or smaller studies. These interventions are not guaranteed to replace medication for all patients. Discuss with your doctor whether any of these are appropriate for your clinical situation.
Global Prescribing & Pricing
Widely recommended as a first-line medication for type 2 diabetes across major guidelines globally
United States
$4–10 (generic)/mo
First-line per ADA guidelines; universally used
No lifestyle prerequisite; prescribed by any physician
Almost always covered
United Kingdom
~$2–4/mo
NICE first-line alongside lifestyle counseling
Lifestyle modification recommended but not a hard prerequisite
Fully covered by NHS
France
~$2–6/mo
Universal first-line in French diabetes guidelines
Lifestyle counseling included in standard care pathway at no extra cost
Fully covered by Sécurité Sociale
India
~$0.50–1/mo
Largest global generic producer; widely prescribed
Subsidized under national diabetes programs; exported globally
Subsidized or free at public clinics
WHO Essential Medicines
~$2–5 global/mo
On WHO Essential Medicines List since 1994
Required to be available in all countries' formularies per WHO mandate
Covered in most national formularies globally
Metformin is one of the only medications where US, European, and WHO guidelines fully agree — it's first-line everywhere. Generic production in India keeps global prices at $0.50–$5/month. The US generic costs $4–10, making this one of the few drugs where pricing parity is nearly achieved.
Clinical Trials & Funding
Understanding who funds research helps contextualize results. Industry-funded trials are not automatically invalid — they undergo the same FDA review — but declared conflicts and sponsor effects are worth knowing. All linked trials can be verified on ClinicalTrials.gov.
Funding Sources
UKPDS: UK government funded. DPP: NIH funded. Most major metformin trials are government or non-profit funded, unusual for diabetes drugs.
Declared Conflicts of Interest
Minimal conflicts - largely public-funded research
Key Efficacy Results
A1C -1.5%, weight neutral, possible longevity benefits
Referenced Studies
Each study carries a Cochrane RoB-2 risk-of-bias badge — tap the badge for details.
Evidence & Transparency
Cochrane RoB-2 (Risk of Bias)
Badges reflect an editorial assessment using Cochrane's RoB-2 tool domains: randomization, intervention deviation, missing data, outcome measurement, and selective reporting. These are not certified Cochrane reviews. Learn more ↗
CMS Open Payments
Manufacturer payment disclosures are reported via the CMS Sunshine Act. Disclosure is legally required and does not imply bias or misconduct. Language uses "may," "suggests," or "appears" — never definitive clinical claims. CMS Open Payments ↗
Live Clinical Trials
Live from ClinicalTrials.gov · refreshed every 4 hours
Currently enrolling, active, and recently completed studies involving Metformin. Data is pulled directly from the U.S. National Library of Medicine.
Recent Research
Live from PubMed · peer-reviewed literature · refreshed every 4 hours
Most recently indexed clinical trials and systematic reviews mentioning Metformin in PubMed.
Source Documentation
Structured citations for referenced clinical trials
Each referenced trial is listed with its registry ID, funding source, and bias assessment. Use the copy button to generate a formatted citation.
| Trial | Registry ID | Cite |
|---|---|---|
| DPP (NIH) | NCT00004992 | |
| MILES (Metformin Longevity) | NCT02432287 |
Bias ratings use Cochrane RoB-2 methodology. Editorial assessment — not a certified Cochrane review.
Our MethodologyMedical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Stopping This Medication Safely
Metformin has no physical withdrawal syndrome. However, blood sugar typically rises without lifestyle compensation, and abrupt stopping is not recommended for patients with poor glycemic control.
What Published Research Shows About Stopping This Medication
This summarizes what published research documents — it is not personal medical advice. Any changes to your medication require discussion with your prescribing physician.
- ·Research supports establishing a low-carbohydrate or Mediterranean diet before stopping
- ·Clinical guidelines describe 150 min/week of exercise as beneficial preparation before stopping
- ·Published approaches describe dose reduction of 50% for 2–4 weeks in patients on high doses (1500–2000mg)
- ·Research recommends monitoring fasting blood glucose daily for 4 weeks after stopping; HbA1c reassessment at 3 months is documented clinical practice
Warning Symptoms — Contact Your Doctor If You Experience:
- Fasting blood glucose rising above 130 mg/dL
- Increased thirst or urination
- Fatigue
- HbA1c above target at 3-month check
Never change or stop a medication without consulting your prescribing physician.
Questions for Your Doctor
Questions to Ask
- 1.Could I try lifestyle changes first?
- 2.Should I take B12 supplements?
- 3.Would extended-release reduce GI side effects?
- 4.What A1C should we target?
Lab Tests to Request
- HbA1c
- Kidney function (eGFR, creatinine)
- Vitamin B12
- Fasting glucose
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Frequently Asked Questions About Glucophage®
- What is Glucophage® used for?
- Glucophage® (Metformin) is a Biguanide manufactured by Generic. FDA-approved indications include: Type 2 diabetes; Pre-diabetes (off-label); PCOS (off-label).
- What are the common side effects of Glucophage®?
- Common side effects of Glucophage® include: Nausea (25%); Diarrhea (28%); Stomach upset / cramping (20%); Vomiting (7%); Metallic taste in mouth (15%).
- How much does Glucophage® cost?
- Glucophage® list price is approximately $30. With insurance it typically costs $4; without insurance approximately $10-20.
- Who funded the clinical trials for Glucophage®?
- UKPDS: UK government funded. DPP: NIH funded. Most major metformin trials are government or non-profit funded, unusual for diabetes drugs.
- How strong is the clinical evidence for Glucophage®?
- Key studies: UKPDS (gold standard), DPP, Cochrane meta-analysis. A1C -1.5%, weight neutral, possible longevity benefits Potential conflicts of interest: Minimal conflicts - largely public-funded research.
- Are there non-drug alternatives to Glucophage®?
- Lifestyle intervention reduced T2D risk by 58% in a landmark NIH-funded trial (Diabetes Prevention Program, 2002) See the Alternatives tab for full details.
Get notified when we update Glucophage®
We'll email you when new evidence, safety updates, or alternatives are added.
No spam. Unsubscribe anytime.