A decades-old diabetes drug now holds promise for increasing healthspan. Research shows that metformin may reduce the risk of some of the diseases of aging, thus increasing the number of years someone is healthy.
Metformin, also known as Glucophage, is the most commonly prescribed medication for reducing blood glucose levels. Metformin prescriptions target people with diabetes, prediabetes, and sometimes for PCOS (polycystic ovarian syndrome).
Beyond diabetes, there are also many studies pointing to other positive benefits for metformin as a longevity or healthy aging medication.
Metformin has a couple of mechanisms of action:
Let’s take a close look at all three of these actions of metformin:
Decreases glucose production in the liver:
When glucose levels in the body fall, such as when fasting or even overnight when sleeping, the liver can produce glucose through a process called gluconeogenesis. This keeps glucose levels in the right range all day and night for people without diabetes.
The research on exactly how metformin decreases gluconeogenesis (glucose production) in the liver isn’t fully elucidated. There seem to be several possibilities:
New research also questions whether metformin reduces glucose production in the liver for people without type 2 diabetes. The studies indicate that glucose production in the liver may not decrease – and may possibly increase a bit to counteract the drop in blood glucose levels.[ref][ref]
Increases glucose uptake:
Blood glucose levels remain tightly regulated, and the release of insulin by the pancreas facilitates the uptake of glucose into cells. For most cells, glucose can’t cross the cell membrane without a transporter. The glucose transporters are known as GLUT1 through GLUT4, with different transporters in different cell types. The GLUT4 transporters are found in muscle tissue and fat cells. When blood glucose levels are high, the GLUT4 transporters are located in the cytosol of the cell (inside the cell), but when glucose levels fall, insulin levels rise. Insulin then binds to a receptor on the cell membrane, causing a cascade of actions that results in the GLUT4 transporters moving to the cell membrane. There, they can move glucose into the cells.
Metformin is thought to work in a way that keeps the GLUT4 transporters available on the cell surface so that the skeletal muscle cells can take up more glucose without needing more insulin. [ref]
Altered microbiome composition:
Research also shows that metformin alters the composition of the gut microbiome, promoting Akkermansia muciniphilia, a bacteria associated with a lower risk of obesity and lower risk of inflammatory conditions in the intestines. The altered gut microbiome composition may also be a mechanism through which metformin helps with diabetes. Additionally, metformin has shown to increase short-chain fatty acid metabolism in the intestines. [ref][ref][ref]
Polycystic ovarian syndrome (PCOS) is characterized by insulin resistance and altered androgen hormone production. Studies show that metformin may be beneficial for women with PCOS. One study found that 12 weeks of metformin decreased testosterone levels and improved glucose effectiveness.[ref]
Many researchers are now looking at aging as a disease. In fact, the World Health Organization recently added it to its classification system as a disease. With this idea in mind, let’s take a look at the use of metformin to prevent chronic diseases in aging.
Animal studies have repeatedly shown that metformin can increase lifespan. Most of the studies show that starting metformin in middle age or earlier can increase lifespan and healthspan.[ref][ref][ref]
But humans aren’t the same as mice, and the results of animal studies sometimes don’t hold true for people.
Human studies on metformin show:
A large meta-analysis found that people with diabetes and also taking metformin had lower all-cause mortality than non-diabetics. They also had lower cardiovascular disease and cancer rates. That is pretty amazing. The study also showed that diabetics taking metformin had lower rates of cancer than diabetics using other types of diabetes medications. [ref]
Another meta-analysis using data from over 1 million patients found that both all-cause mortality and cardiovascular events were reduced significantly (20% for all-cause mortality and over 30% for cardiovascular events). [ref]
Other studies show that all-cause mortality and cancer-related mortality is reduced in people who take metformin.[ref]
Not all human studies show fantastic results:
In a study of heart attack patients, 4-months of metformin did not have beneficial long-term effects. [ref] Other studies show a possible impact that negates the benefits of aerobic exercise.[ref]
One mechanism (other than decreased blood glucose levels) for a positive effect on healthy aging is that metformin may activate SIRT1. The sirtuins are a family of enzymes that are important for regulating cellular homeostasis, and SIRT1 (sirtuin 1) is important in healthy aging. A link exists between the activation of SIRT1 and lower rates of cardiovascular and metabolic diseases.[ref][ref]
Another mechanism through which metformin has been shown to act is in the way that mitochondria use fatty acids for energy. The ACAD10 gene codes for an enzyme needed in beta-oxidation and animal studies show that metformin acts through the inhibition of mTORC1 to upregulate ACAD10. [ref]
A Dec 2019 randomized crossover trial shows that 4 days of metformin doesn’t impact skeletal muscle activity. Interestingly, the authors note that metformin caused the participants to feel like exercise took more exertion. Thus, it may cause people to want to exercise a little less. [ref]
Another study in older adults (age ~62), 3 months of metformin seemed to attenuate the benefits of aerobic exercise. [ref]
Most importantly, there is an increased risk of lactic acidosis in people taking metformin. This may be more of a risk for people with underlying kidney problems. [ref]
Some people have gastrointestinal side effects from metformin. People with SLC22A1 variants (below) are more likely to have gastrointestinal problems.[ref]
Metformin circulates unbound because its metabolism doesn’t occur in the liver. Instead, the kidneys clear it from the body facilitated by SLC22A2 kidney cells. (more on this below) [ref]
Like almost every drug or supplement, not everyone responds the same way to metformin. Below you can find some of the genetic variants associated with the altered response to metformin.
The TCF7L2 gene codes for transcription factor-like 2, which plays a role in beta-cell function.
Check your genetic data for rs7903146 (23andMe v4, v5; AncestryDNA):
SLC22A1 gene codes for the organic cation transporter 1, which is the main transporter of metformin into liver cells, where it acts to alter blood glucose levels.
Check your genetic data for rs622342 (23andMe v4, v5; AncestryDNA):
Check your genetic data for rs12208357 (23andMe v4, v5; AncestryDNA):
The SLC22A2 gene codes for the organic cation transporter 2, which is the main transporter in the kidney cells that drives excretion of metformin through the urine.
Check your genetic data for rs316019 A270S (23andMe v4, v5; AncestryDNA):
If you are interested in metformin for longevity, talk with your doctor about getting a prescription. Alternatively, there is an online website that sells 3-month prescriptions of metformin, after you interact with their telemedicine doctor. The website is called qualytude.com. Read through the information and be sure to understand the terms of the website.
Berberine is a natural supplement that is often touted as a natural alternative to metformin. Read more about berberine.
Longer-term use of metformin increases the risk of vitamin B12 deficiency. [ref] Consider supplementing with vitamin B12, especially if you don’t eat a lot of foods that contain B12.
Explore the research about how nicotinamide riboside (NR) and NMN are being used to reverse aging. Learn about how your genes naturally affect your NAD+ levels, and how this interacts with the aging process.
Your telomeres are the region at the end of each chromosome that keeps your DNA intact when your cells divide. Telomeres that get too short cause cells to stop dividing, leading to some of the diseases of aging.