A potential miracle drug already used as a treatment for diabetes and other diseases has taken centre stage in the fight against ageing.

We often think of ageing as the one battle we can never win. Yes, life expectancy has been climbing slowly for decades, but the chances that you’ll live past 100 are still, realistically, vanishingly small. And yet there are whole teams of scientists around the word who treat ageing not so much as an inevitability than as a sickness that can be fought, and if their efforts succeed, your children might well be living longer than we can even imagine.

Nir Barzilai is the director of the Institute for Aging Research at the Albert Einstein College of Medicine in New York and he goes to work every day with the goal of increasing the number of healthy, happy years that human beings can live.

He has humbly referred to his own work – which centres around fighting ageing using a simple, cheap pill that you would take every day – as a journey to “the promised land’ and “history making”.

His work might sound like it’s at the edge of serious science, and that was long the case for anti-ageing experts, but Barzilai visited the Vatican last year as part of a global conference on cellular therapies, which featured many of the world’s top cancer scientists.

And it’s not just scientists, or the church, who are excited about the possibility. While rumours abound of the world’s billionaires attempting to extend their charmed lives by injecting themselves with the blood of young people, they are also pouring their funds into anti-ageing biotech research. Jeff Bezos, Larry Ellison, Peter Thiel and Google’s Sergey Brin have all invested heavily in companies that are working on radical fixes for our annoyingly fragile bodies.

Sci-fi sounding ideas like growing new organs using strands of your own DNA, or uploading your consciousness into computers to upgrade your mind as your body degrades are things that are being seriously explored.

To suggest that this is self-serving rather than a case of the epically rich wanting to save the world from the blight of ageing seems self-evident.

What makes Barzilai’s plan different is that he’s not trying to develop some wild and expensive fix for ageing, he’s trying to gain approval for a cheap, generic drug that everyone could afford, and one that he says has already shown, through clinical trials, the ability to help beat back the worst parts of ageing.

It’s called metformin and costs a wondrous-sounding five cents per pill, and it uses compound made from a plant called French lilac, or galega officinalis.

This potential miracle drug is already used as a treatment for diabetes, thanks to its ability to keep blood-sugar levels stable.

Barzilai has been studying metformin since the 1980s and has discovered that the diabetics who take it not only beat back their disease, but they tend to be healthier in many ways, and to have fewer cardiovascular problems. More excitingly, they get cancer less frequently, and live longer.

No less a scientist than James Watson of DNA fame prescribes himself metformin and says that it appears to be “our only real clue into the business” of fighting cancer.

“Metformin may have already saved more people from cancer deaths than any drug in history,” – Lewis Cantley

Other high-profile brainiacs who already take metformin include famous futurist Ray Kurzweil (who claims it’s improved his eyesight) and Ned David of Silicon Valley firm Unity Biotechnology, which is yet another company working on anti-ageing drugs of its own.

Lewis Cantley, the director of the Cancer Center at Weill Cornell Medicine, says: “Metformin may have already saved more people from cancer deaths than any drug in history.” And it’s achieved that feat largely by accident, while being given to treat other diseases.

Stopping cancer alone won’t be enough for scientist’s like Barzilai, of course. He believes our current approach of treating the ailments that become more likely to attack us as we age – cancer, Alzheimer’s, heart disease – is the wrong way forward. Or a dead end, if you will.

“Unless we target ageing itself,” he told Wired magazine, “all we can hope is that we switch one disease for another.”

America’s all-powerful FDA will not decide on whether metformin can be sold as the country’s first official anti-ageing drug until a study called Targeting Aging with Metformin (TAME) has completed a rigorous trial involving around 3,000 people between the ages of 65 and 79.

The trial will cost US$69 million and Barzilai is still sourcing the funding, at least some of which he says will come from a billionaire he’s not willing to name. Drug companies are not hugely keen on getting involved with a drug that’s so cheap.

“Rich people are interested in ageing,” he says. “They call me to prescribe metformin, but they don’t understand that I’m doing something that’s more profound.”

Increasing the lifespan of human beings everywhere at a cost of just a few cents a day is very profound indeed.