A 2014 study at Cardiff University of more than 180,000 people found that when patients with diabetes were given metformin they lived longer than those without the condition. “That was the big leap to, ‘Wow, we should take it, why are diabetics healthier than we are’,” says Dr Lauren Bramley at Dr Bramley & Partners, a medical practice in Hong Kong’s Centrat district that focuses on wellness.

We tend to lose insulin sensitivity as we age. Metformin’s use as an anti-ageing treatment revolves around the fact that it helps to increase sensitivity to insulin, which in turn lowers blood-sugar levels.

Ageing is also associated with glycation, when sugar molecules stick to your cells, your collagen. The result is a feeling of “brain fog”, the mind is not as sharp as it once was and the body feels heavy. A lot of glycation on our collagen leads to wrinkles.

Type 3 diabetes has been proposed as a title for Alzheimer’s disease, because it results from insulin resistance in the brain.

There is a growing body of evidence that metformin is effective in both the prevention and treatment of cancer. Studies suggest that if you have type 2 diabetes and are taking metformin you have a lower risk of developing cancer than if you do not take metformin. (Having type 2 diabetes is a major risk factor for developing certain cancers.)

Whether or not this is related to being overweight – common in those with type 2 diabetes – the natural production of more insulin or another factor is unknown. Still, in studies using tissue cells, metformin can inhibit the growth of breast, colon, lung, pancreatic and prostate cancer cells.

In a paper published in March in the online Polish journal Postepy Hig Med Dosw, researchers wrote that “Metformin is now attracting the attention of researchers in fields other than diabetes, as it has been shown to have anti-cancer, immunoregulatory and anti-ageing effects.”

The anti-cancer effects of metformin were seen to be two-fold: by directly affecting the inflammatory processes that are reported to play a significant role in tumour progression and indirectly by modifying the blood glucose and insulin levels which can influence the survival of cancer cells.

Dr Nichola Salmond at Optimal Family Health, a medical clinic in Central, has been using metformin to treat patients with type 2 diabetes for more than 20 years. She doesn’t usually prescribe it purely exclusively for anti-ageing, instead reserving it for those with pre-diabetes and insulin resistance which a patient may have because they are overweight or at the stage before pre-diabetes. She has also prescribed it to a patient who is at high risk of Alzheimer’s.

“The main thing some patients notice is that they lose weight or they feel less bloated,” says Salmond, who has been taking metformin herself for seven years.

Her stepfather has been taking metformin for 30 years for his type 2 diabetes and, now in his 80s, she says he is decidedly healthy for his age.

“I always wondered why he was so healthy all the time and then when the anti-ageing news came out I suspected the two were connected. Dementia also runs in his family and his sister got it, but he hasn’t been affected,” says Salmond, adding that metformin has also been proven to extend the wellness and lifespan of mice.

Metformin isn’t just about combating disease. Bramley says that her patients report having more energy and feeling more clear-headed on the medication.

“A lot of what people tell me is they are feeling better and looking younger. It’s not just about avoiding disease but also about looking and feeling better,” says Bramley.

Even her 18-year-old son is taking it. “He knew that I’m interested in metformin, but when he started reading about it in the popular press he wanted to take it because he saw all the anti-ageing phenomenon associated and wanted it,” says Bramley.

She says it is also effective for weight loss – “insulin is very good at telling your body to store fat and sugar as fat, even healthy sugar” – and she has used it to help patients with fatty livers, a common problem in the elderly.

Although there have been no scientific tests on metformin as a hangover cure, anecdotally it is known to be effective.

“If you have too many glasses of wine, if you take metformin on the way to bed, it’s as though a couple of those glasses didn’t happen,” says Bramley.

Jane Moir was prescribed metformin two years ago. She had an underactive thyroid that was not responding to medication and switched to a new practitioner who took a more holistic approach, conducting a number of tests based on how she was actually feeling. She was diagnosed as pre-diabetic.

“My experience on metformin has been all positive. I’m on the slow release version which means I don’t get ‘hangry’ any more – before I was taking it, I couldn’t go for long periods without food. I carried snacks around for the blood-sugar crash moments,” says Moir.

Metformin has a few side effects, the most common being nausea and diarrhoea. These effects can sometimes be avoided or minimised by taking a lower dose or extended release form of metformin. It can also lead to a vitamin B12 deficiency, which is an especially significant risk in diabetics, so anyone on metformin should monitor their B12 levels. Bramley says it can also lower CoQ10 – coenzyme Q10 – which converts food into energy, so that, too, should be monitored.

Metformin is inexpensive. It can cost as little as HK$2 a pill in some countries. One local doctor’s office charges HK$360 for a bottle of 60 tablets. Hong Kong pharmacies stock it, but it is a prescription drug.

“It’s great that it comes out as one of the best anti-ageing drugs in these studies when a lot of anti-ageing treatments are so expensive. It’s such an effective one and costs so little,” says Bramley.