Metformin
biguanide · oral antidiabetic
Our referenceBy the Layer Nutrition editorial team
What this medicine is for
Metformine est un médicament de la catégorie « biguanide (antidiabétique oral) ». La metformine réduit la production de sucre par le foie et améliore la réponse de l'organisme à l'insuline. C'est le traitement de référence du diabète de type 2, pris tous les jours.
Concrètement, pour Metformine : Aide à contrôler la glycémie dans le diabète de type 2. On le prend en général sur la durée, dans le cadre d'un suivi régulier, et on ne l'interrompt pas de sa propre initiative.
Under which brands it is found
En France, on recense environ 41 présentations remboursables contenant Metformine. On la trouve sous plusieurs noms de marque et en génériques.
- Glimezit
- Glucophage
- Glucovance
- Janumet
- Metformine Accord
- Metformine Almus
- Metformine Arrow Lab
- Metformine Bgr
- Eucreas
- Metformine Eg Labo
- Metformine Viatris
- Vildagliptine/Metformine Biogaran
- and other presentations
Original brand-name products and generics deliver the same active substance; the choice between them is made with your doctor or pharmacist.
Our product for this treatment
You take Metformin. For people who follow this type of treatment every day, we have designed a dedicated product.
Layer Nutrition Metformin
B12 as methylcobalamin, active folates, thiamine.
B12 1,000 µg · Folate 100 µg · Thiamine 50 mg
One bottle, one dose per day. Reduced price from the second box, free delivery from two boxes.
How metformin works
Metformin belongs to the biguanide family. It enters mainly the liver cells through a transporter called OCT1, organic cation transporter 1, which concentrates its action on that organ. Inside the cells, it inhibits complex I of the respiratory chain of the mitochondria, the cell's power plants. This inhibition reduces the production of ATP, the molecule that stores energy, raises the AMP:ATP ratio and activates AMPK, an enzyme that senses the cell's energy state.
Its central effect is to slow hepatic gluconeogenesis, the production of glucose by the liver. By producing less sugar, the liver releases less into the blood and blood glucose falls. According to studies on its mechanism, metformin may also inhibit mitochondrial glycerophosphate dehydrogenase, mGPD, an enzyme of the glycerophosphate shuttle, which would limit the production of glucose from glycerol and lactate. The importance of this pathway at therapeutic doses remains debated. These levers act on the liver rather than on the pancreas.
Why it is prescribed and how to take it
Metformin is prescribed in type 2 diabetes to lower blood glucose. Its action rests on the pharmacology described above: by slowing the production of glucose by the liver, it reduces the amount of sugar released into the blood between and during meals. It is not metabolised by the liver and is eliminated unchanged by the kidney, with a half-life of about 6.2 hours. This renal elimination explains why kidney function governs its use.
In daily use, it is taken during or after a meal, spread over two to three doses a day, which follows its relatively short half-life. The dose is increased gradually at the start of treatment to improve digestive tolerance. Taking the doses regularly supports blood glucose control throughout the day. It should not be stopped on one's own initiative: any adjustment is decided with the doctor who oversees the treatment.
The effects to know about
Digestive disturbances are the most common effects: nausea, vomiting, diarrhoea, abdominal pain and loss of appetite. They are very common, with a frequency of at least 1 person in 10, occur mainly at the start of treatment and most often resolve on their own. Taking the medicine with a meal and increasing the dose gradually are aimed precisely at limiting them. A taste disturbance, often a metallic taste, is common, with a frequency of at least 1 in 100 and less than 1 in 10.
Lactic acidosis is a very rare effect, fewer than 1 case in 10,000, but serious. Its risk rises above all in cases of renal failure, heart failure and alcohol consumption. A Cochrane review found no case of lactic acidosis over 70,490 patient-years of exposure to metformin, the upper limit of the estimated incidence being 4.3 cases per 100,000 patient-years, a figure comparable to that of untreated patients. Medical follow-up targets precisely the situations where this risk rises.
Vitamin B12
Metformin reduces the absorption of vitamin B12. The documented mechanism is a calcium-dependent interference with the binding between intrinsic factor and vitamin B12 in the terminal ileum, the last part of the small intestine where this vitamin is taken up. Disrupted at this point, dietary B12 passes less well into the body. The effect sets in mainly over time.
Since June 2022, the British medicines agency, the MHRA, has classified the fall in vitamin B12 as a common effect of metformin, affecting up to 1 person in 10, especially at high doses or during prolonged treatment. It recommends measuring B12 in patients at risk or showing symptoms. This measurement is among the markers that follow-up can check. It points towards supplementation when the fall is confirmed.
On the plate
Vitamin B12 is the point where the plate meets what the treatment shifts. It is found only in foods of animal origin: fish, meats, poultry, eggs, milk and dairy products. Plant foods do not contain it naturally, except when they are fortified. A plate that regularly makes room for salmon, eggs, cheese or meat therefore supports the starting intake.
This dietary intake keeps all its value, but it meets a limit specific to metformin. When the medicine hinders the uptake of B12 in the ileum, increasing the share of these foods does not always close the gap, since it is the absorption step that is at issue. This is where a targeted intake makes sense, in addition to your treatment, never in its place. The choice of dose is then read together with the biological follow-up.
Interactions and monitoring
Kidney function governs the use of metformin, since the kidney eliminates it. It is contraindicated when the estimated glomerular filtration rate, the eGFR, is below 30 mL/min/1.73 m². Between 30 and 44, the dose is reduced to a maximum of 1,000 mg per day. Kidney function is assessed before starting and then at least once a year.
Certain situations require stopping the treatment: an examination with iodinated contrast medium in patients with reduced kidney function, between 30 and 60 eGFR, liver damage, alcoholism, heart failure or an intra-arterial injection. Kidney function is then reassessed 48 hours later before resuming. Alcohol increases the risk of lactic acidosis: its metabolism shifts the NAD+/NADH ratio towards NADH, which reduces the liver's ability to eliminate lactate. These points frame the dialogue with the care team.
Sources
- Cellular and Molecular Mechanisms of Metformin Action
- The Metformin Mechanism on Gluconeogenesis and AMPK Activation: The Metabolite Perspective
- Metformin: From Mechanisms of Action to Therapies
- Metformin, StatPearls
- Metformin 500 mg Tablets, Summary of Product Characteristics (SmPC)
- Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus
- Drug Safety Update June 2022: advice on metformin and reduced vitamin B12 levels
- Metformin, NICE guidance regarding renal function
- Glucophage (metformin) prescribing information
- Vitamin B12, Office of Dietary Supplements
Related molecules
To explore within the “Diabetes and blood sugar” family and its neighbors.
See the entire “Diabetes and blood sugar” family · Back to the atlas
Frequently asked questions
What are the side effects of metformin?
The most common ones are digestive: diarrhea, nausea, abdominal pain and bloating, often at the start of treatment. The full list and how often they occur are set out in the patient leaflet. If a side effect is bothersome or persistent, talk to your doctor or pharmacist.
Does metformin cause weight loss?
Metformin is an oral antidiabetic medication, not a weight-loss drug. Some people may notice a change in weight. Any question about how you use it and your goals is for your doctor, who decides on the indication.
Metformin 500, 850 and 1000: what is the difference?
These numbers correspond to different strengths of the same metformin hydrochloride. The choice of strength and dosing schedule is a medical decision, set out in your prescription and detailed in the patient leaflet. Do not change anything without your doctor.
What is lactic acidosis on metformin?
It is a rare but serious side effect flagged in the patient leaflet, with signs such as muscle cramps, abdominal pain and severe fatigue. If these signs appear, stop taking it and seek emergency care. The at-risk situations are specified in the leaflet and by your doctor.
Can you drink alcohol while taking metformin?
The patient leaflet recommends avoiding excessive or regular alcohol consumption, which can increase the risk of lactic acidosis and worsen digestive problems. For your specific situation, ask your doctor or pharmacist for advice.
Metformin and pregnancy: what you should know
Metformin is sometimes used during pregnancy on medical advice. If you are pregnant, breastfeeding or planning a pregnancy, do not adjust anything on your own: talk to your doctor, who will weigh the benefits and risks. The patient leaflet covers these situations.
What are metformin's interactions with other medications?
Metformin is often combined with other diabetes treatments (sitagliptin, dapagliflozin, analogues such as semaglutide). These combinations, like any interaction, are for your doctor. Tell your pharmacist about all your medications and refer to the patient leaflet.
Is metformin dangerous for the elderly?
In elderly people or in the event of a kidney problem, particular monitoring is mentioned in the patient leaflet, especially of kidney function. This assessment is for your doctor, who adjusts the follow-up. Do not make any decision without them.
What to do about a missed dose or stopping metformin?
What to do about a missed dose is set out in the patient leaflet. Never stop metformin on your own: any change must be decided with your doctor or pharmacist.
Can metformin affect vitamin B12?
Research links long-term metformin treatment to a decline in vitamin B12 status: the trial by de Jager et al. (BMJ, 2010) and then the work by Aroda et al. (2016) associate treatment duration with a decrease in B12 concentrations. This is the nutrient to consider first with MT01.
Should you monitor your vitamin B12 when taking metformin?
In 2022, the UK medicines agency (MHRA) recommended considering periodic monitoring of vitamin B12 in at-risk people on long-term treatment. A B12 blood test is requested and interpreted with your doctor; MT01 supports this approach without replacing it.
Which form of vitamin B12 is best with metformin?
When vitamin B12 supplementation is considered, methylcobalamin is a directly absorbable form, chosen for MT01. Whether to use a supplement and how relevant it is to your situation are decided with your doctor, in light of your blood test.
Ces réponses portent sur le volet nutritionnel. Pour toute question sur votre médicament, la notice et votre médecin ou pharmacien font foi.