Thuốc GLP-1 như Ozempic cho thấy tiềm năng không chỉ giới hạn ở việc giảm cân. Nhưng đâu là khoa học thực tế và đâu là lời thổi phồng?

You’ve probably heard of Ozempic or Wegovy. These are the injectable drugs that have become household names for weight loss and diabetes.

Now, researchers are investigating whether these medications known as GLP-1 agonists or GLP-1 drugs could treat everything from cancer and brain disease to depression, addiction and endometriosis.

Some findings are genuinely exciting. Others are being oversold. Here’s what the science actually says.

First, how do these drugs work?

GLP-1 (glucagon-like peptide-1) is a hormone your gut naturally releases after eating. It tells your pancreas to produce insulin and signals to your brain that you’re full. These drugs mimic that hormone.

But GLP-1 receptors aren’t just in the gut. They’re found in the heart, kidneys, liver and brain. That’s what makes scientists think these drugs might do far more than manage weight.

Where the evidence is already solid

Beyond diabetes and obesity, GLP-1 drugs have now earned regulatory approval in several new areas.

A trial of more than 17,000 people found semaglutide (the active drug in Ozempic/Wegovy) cut the risk of serious heart attacks and strokes by 20%, even in people without diabetes.

In a trial of almost 1,200 patients, semaglutide outperformed a placebo in treating a type of advanced liver disease.

Tirzepatide (Mounjaro) has also been shown to significantly reduce the severity of sleep apnoea, mostly because weight loss puts less pressure on the airways.

GLP-1s and cancer: promising but no clinical trial evidence

Obesity is a risk factor for at least 13 cancers, so reducing weight using GLP-1 drugs can also be expected to limit cancer risk. This was shown in a study of 86,000 adults with obesity. It found GLP-1 users had a 17% lower cancer risk.

New data suggests GLP-1 users were also less likely to see cancer spread to other organs, but this work is yet to be verified by other researchers. The anti-inflammatory effects of these drugs, which appear to work independently of weight loss, may be playing a role.

However, there have not yet been any well-controlled clinical trials that establish the link between GLP-1 drugs and preventing cancer.

Endometriosis: early but promising signs

Endometriosis affects roughly one in ten women of reproductive age. This is where tissue similar to the womb lining grows outside the uterus.

Because GLP-1 receptors are also present in reproductive tissue, these medications have shown promise in improving symptoms, with a survey of 161 women supporting this.

But, similar to cancer, there are no randomised human trials.

Addiction and smoking

GLP-1 receptors are concentrated in the brain’s reward pathways. These same circuits drive cravings for alcohol, nicotine and drugs.

An analysis of more than 1.3 million people found GLP-1 users had significantly lower rates of opioid overdose and alcohol intoxication.

A randomised trial found semaglutide reduced drinking in people with alcohol use disorder.

Early quit-smoking trials are encouraging, too.

The brain: the least clear picture for GLP-1 therapy

This is where the story gets genuinely complicated.

There are real biological reasons GLP-1 drugs could help with neurodegeneration and mental ill-health. They reduce brain inflammation, interact with dopamine (the brain’s motivation chemical) and support the gut-brain axis (the communication network that carries signals to and from the gut and brain) .

However, current clinical evidence is conflicting.

For Alzheimer’s disease, researchers gave 204 participants with mild to moderate disease liraglutide (a GLP-1 that pre-dated Ozempic) and measured how much brain volume they lost. Those taking the drug showed significantly less shrinkage in key brain regions, including their temporal lobe and overall grey matter.

However, a large phase 3 trial of oral semaglutide found it wasn’t effective at slowing clinical disease progression.

Similarly, exenatide (another earlier GLP-1) showed no evidence for disease modification in a phase 3 Parkinson’s disease trial.

For mental health, current evidence is also mixed. Meta-analyses and large cohort studies show significant reductions in depression and anxiety scores among GLP-1 users.

But a separate observational study found people on these drugs had almost double the risk of major depression.

Another paper found that people with a genetic tendency toward low dopamine levels may face higher risk of depression and suicidal thoughts on these medications.

There are also case reports of serious psychiatric episodes appearing within weeks of starting treatment.

We don’t yet know who these drugs will help, and who they could seriously harm.

What we need to be cautious about

Crucially, most of the new uses for these medications haven’t yet been tested in proper clinical trials. Large real-world studies are useful, but they can’t rule out crucial confounding factors. This means the effects may be due to external influences.

For example, most major GLP-1 trials have enrolled people with obesity or diabetes. People with mental health conditions, neurodegenerative diseases, or addiction were largely excluded. Yet, these are the very populations now being considered for treatment.

Long-term effects are also unknown. A study of more than 200,000 patients found a 2–2.5 times higher risk of drug-induced pancreatitis (dangerous inflammation of the pancreas) .

Rapid weight loss also strips lean muscle, not just fat, affecting strength and metabolism, especially in older adults.

Studies have also indicated these medications carry a risk for thyroid cancer, prompting a warning on drug labels, but evidence is highly conflicting.

Time and further research will tell, but there are genuine safety concerns associated with the widespread use of these medications.

So, while the science here is genuinely exciting, we should continue to approach with informed caution.

Paul Joyce receives funding from The Hospital Research Foundation, Cancer Council SA, and the Australian Research Council. He is director of the Australian Controlled Release Society.