Anyone dealing with type 2 diabetes quickly bumps up against the question: which medication works best? Metformin has been around for decades, sort of the old reliable. It’s almost everyone’s starting point, thanks to its proven ability to lower blood sugar by reducing glucose production in the liver and improving insulin sensitivity. You’ve probably heard about metformin—even people without diabetes talk about it for off-label uses like weight loss.
GLP-1 agonists, with names like semaglutide, liraglutide, and dulaglutide, belong to a much newer family. They mimic a hormone (GLP-1) in your body that helps lower blood sugar after eating, makes you feel full, and slows how fast your stomach empties. Originally, these were injectables, but pills are finally hitting shelves too. The way they work—hitting multiple pathways—makes them stand out from most older diabetes drugs.
One key thing to know: metformin is almost always a pill, while GLP-1 agonists are still mostly shots, usually once weekly or daily. That difference alone puts some people off. But there’s no denying the buzz around GLP-1 drugs; they’re getting headlines for helping patients lose substantial weight and for potentially protecting the heart and kidneys as well as controlling diabetes.
So what happens when we compare them directly? Start with the big question—how well do they actually lower blood sugar?
Here’s the thing: metformin works really well for the majority of people right out of the gate. In clinical trials, it typically drops HbA1c levels—the number your doctor cares about most—by around 1-1.5%. For many Australians diagnosed today, that’s enough to hit the immediate target.
But GLP-1 agonists usually score even higher in studies. Randomised trials, like the landmark SUSTAIN-7 and AWARD-6, found drugs such as semaglutide and dulaglutide cut HbA1c by as much as 1-2%. That edge seems small on paper, but if your blood sugar is stubborn, it can be a game changer. People who take GLP-1 agonists also tend to shed more weight—a big bonus given how particularly stubborn weight loss is with diabetes. In one real-world study from 2023, semaglutide users lost on average 5-8 kg more than those on metformin alone.
A key fact: almost every international guideline still says start with metformin, unless you have heart or kidney problems, or extreme obesity. But more specialists are pushing for GLP-1 agonists sooner rather than later, because of those weight and heart benefits. After all, the majority of type 2 diabetes patients eventually need two or more drugs. So why not address the broader picture sooner?
"The latest evidence shows GLP-1 agonists not only lower blood sugar more than metformin alone, but also help achieve meaningful weight loss and reduce major cardiovascular events,” says Dr. Amanda Thornton, endocrinologist at the Royal Melbourne Hospital.
There’s more nuance here, too. Metformin is less likely than a GLP-1 to cause low blood sugar, and it works at a lower cost. GLP-1s, however, are showing up as the clear winners for people at risk of heart attack or stroke. Some, like semaglutide, are even approved to help with weight loss for people without diabetes.
When you start comparing medications, side effects can make or break the right choice. Metformin’s big drawback is digestive upset: think nausea, diarrhoea, and sometimes a metallic taste. For most, this fades in a few weeks—especially if you take it with food or choose the extended-release version.
GLP-1 agonists have their own brand of squeamishness. About half of people experience some sort of stomach trouble when they first start: queasiness, vomiting, and sometimes diarrhoea or constipation. The nausea is famous, but often gets better after a month. Still, for some, it’s too much—even with careful ‘step-up’ dosing. There are rare but important risks, too: cases of pancreatitis have happened, and people with certain family histories (like thyroid cancer) should be extra cautious.
What about longer-term safety? Metformin, after all these years, is considered incredibly safe except for people with severe kidney problems. But a few people on metformin can develop vitamin B12 deficiency, so it’s something to watch for on blood tests every year or two.
Compare this to GLP-1 agonists, which are so new we’re still gathering all the long-term data. The diabetes community is excited by evidence that these drugs can help prevent heart attacks, kidney troubles, and strokes—especially in people with existing cardiovascular issues. Still, real-world experience is less than a decade old, which means some safety questions linger. Balancing the impressive upsides against uncommon but real risks is part of every decision.
Worried about weight gain? Metformin is usually weight-neutral; it won’t help you lose much, but you shouldn’t gain either. GLP-1s, on the other hand, consistently trigger weight loss, sometimes significant, even in people who’d previously struggled with the scales for years.
If you’re digging into these side effects to help guide your next prescription, you might also want to see an up-to-date guide on alternatives to metformin for diabetes, since there’s more than just the old blue pill and the new injectables on offer.
This is where people in real life hit speed bumps. Metformin is famously cheap—some scripts fill for only a few dollars with a concession card under the Australian PBS. Even without subsidies, it’s affordable here and across the globe.
GLP-1 agonists, unfortunately, are pricey. As of 2025 in Australia, standard PBS rebates only cover these drugs for certain subsets of patients, usually those who’ve failed on other therapies or have established cardiovascular disease. Out of pocket, they can run from $120 to $150 per month (or more), which stings even for well-insured folks. That’s a big ask when diabetes treatment is for life.
| Medication | Typical Monthly Cost (AUD) | PBS Subsidy Available? |
|---|---|---|
| Metformin | $5 - $20 | Yes, widely |
| Liraglutide | $130 - $160 | Limited |
| Semaglutide | $125 - $150 | Limited |
You’ve also got to factor in that GLP-1 agonists might not be available at all in rural or regional pharmacies, and there’s occasionally a supply crunch—especially when social media drives demand. If you’re traveling, metformin takes up no luggage space and is temperature stable, while GLP-1s travel in coolers with ice bricks unless you have the pill form, which only one brand currently does with broad distribution.
Tip: Anyone struggling to afford new diabetes treatments should talk to their GP or endocrinologist, as patients in certain risk groups may become eligible for subsidised GLP-1 therapy after demonstrating need, especially if other options have failed or side effects become intolerable. Don’t assume paying full price is the only way.
This isn’t an abstract debate—it plays out in clinics every day. Take Jenny, a 58-year-old with newly-diagnosed type 2 diabetes and a family history of heart disease. Her GP started her on metformin (easy, cheap, worked quite well), but weight loss was tough, and her cholesterol stayed stubbornly high. A switch to semaglutide helped with both: better blood sugar AND 7 kilos gone in six months, but it involved out-of-pocket expenses and monthly scripts at the major pharmacy downtown.
Then there’s Glenn, a tradie with a physically demanding job in the heat. He tried GLP-1, but the nausea made it impossible to keep working. Going back to metformin made life much smoother. For some, convenience is king—and swallowing a small, stable pill before tea wins out over needles and unpredictable tummy upsets.
When picking a first-line therapy, doctors usually ask:
There is no universal right or wrong here. Some people love the appetite suppression of GLP-1 agonists and are happy to trade up for cost and weekly injections; others don’t want the hassle or hit to their pharmacy bill. Both drugs can be combined if single therapy doesn’t get blood sugars to target—metformin plus a GLP-1 is actually a really common combo now in specialist clinics around Australia.
Just don’t get discouraged if you need to try more than one option. Modern diabetes management is all about personalization. Keep up regular check-ins with your care team, and check for the latest guidelines. In 2024, the American Diabetes Association pointed out how quickly the landscape is shifting: “Optimal diabetes therapy increasingly means tailoring medications to individual goals, side-effect tolerances, and wallet size,” said their recent Standards of Care report.
Curiosity pays off as well—medication marketing changes month by month, and what’s too expensive or hard to find today could become mainstream by 2026 or later. Stay open to new studies and updated recommendations so you’re not getting stuck with yesterday’s options.
Written by Diana Fieldstone
View all posts by: Diana Fieldstone