How does metformin work in your body?
Metformin lowers blood sugar primarily by causing the liver to produce less new glucose, without the risk of dangerously low blood sugar. Exactly how all the pieces of the mechanism fit together is not yet fully clear.
Metformin acts primarily in liver cells. It mildly and temporarily inhibits a component of the energy-producing machinery in those cells, leaving the cell with less energy available. That lower energy state is the signal that prompts the liver to produce less new glucose. This is the drug's main blood-sugar-lowering effect.
At the same time, that lower energy state in the cell activates a protein that functions as a kind of energy sensor. This protein then adjusts a series of processes: fat production in the liver decreases, the burning of fatty acids increases, and sensitivity to insulin improves. This protein is not strictly necessary for the blood-sugar-lowering effect itself, however; that effect runs through a slightly different pathway.
A third mechanism inhibits the action of glucagon, a hormone that normally prompts the liver to produce extra glucose. In addition, there is evidence, mainly from animal studies, that a specific liver enzyme is inhibited, making it harder for lactate and glycerol to be converted into glucose.
The gut is an underappreciated site of action. Metformin increases the release of a hormone that promotes insulin production there, and it alters the bile acid pool and the composition of the gut bacteria. How much this contributes to the overall effect is not yet precisely known.
An important safety advantage: metformin does not itself stimulate insulin release. As a result, dangerously low blood sugar does not occur, something that is a genuine risk with other diabetes medications. Despite decades of research, the full mechanism of action has not yet been completely elucidated; how much weight each of these mechanisms carries is still a subject of scientific debate.
This answer is based on multiple comprehensive review studies of metformin research. The effect on the energy-producing machinery of the liver cell and the influence on glucose production are broadly supported and have been established as causal. The effects via the cell's energy sensor and via the gut are plausible but less definitively proven. The effect on muscle cells is limited to animal research. All sources note that the complete molecular picture is not yet fully understood.
Does metformin help with weight loss?
Metformin helps with weight loss, but the effect is modest: expect a few kilograms, not a dramatic transformation. Lifestyle changes work better in the short term, but weight loss with metformin remains stable over the long term. Discuss it with your doctor if you want to know whether it suits your situation.
Does berberine help against high blood sugar (the natural metformin)?
Approach this with caution. Berberine measurably lowers blood sugar, but EFSA was unable to establish a safe intake level due to indications of DNA damage and liver injury, an EU procedure is underway that could lead to restrictions, and it has strong interactions with medications. Do not use it on your own, especially not alongside diabetes medication or during pregnancy.
What does taurine do in your body?
Taurine has demonstrable functions in the retina, the heart and the brain, and its importance for infants is well-established enough to warrant its standard inclusion in infant formula. For ageing and weight management, the evidence in humans is still too thin to draw conclusions.
What is metabolic syndrome and how do I get rid of it?
Regular aerobic exercise and a diet with less processed meat and sugar and more wholegrains are the best-supported ways to tackle metabolic syndrome and lower your risk of heart disease and stroke.
What are the side effects of metformin?
Metformin causes gastrointestinal complaints such as diarrhoea, nausea and vomiting in a substantial proportion of users. Discuss with your doctor whether the dose can be built up gradually, or consider an alternative if the complaints persist.
Does metformin help you stay healthy for longer?
Metformin can largely prevent diabetes in people with prediabetes or metabolic syndrome, and that brings real health benefits. Whether it also slows ageing in healthy people has not yet been demonstrated.