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GLP-1s

Semaglutide vs liraglutide

Robbie Puddick
Written by

Robbie Puddick

Medically reviewed by

Fiona Moncrieff

8 min read
Last updated February 2024
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Jump to: Semaglutide VS liraglutide: weight loss | Semaglutide VS liraglutide: type 2 diabetes | Semaglutide VS liraglutide: side effects and safety | Take home message

Semaglutide is generally more effective than liraglutide at supporting weight loss and reducing blood sugar levels for people living with obesity and type 2 diabetes.

Head-to-head randomised controlled trials have shown that semaglutide supports weight loss of around 15%, compared to 5-6% with liraglutide.

These studies have also shown that semaglutide is more effective at reducing blood sugar levels (measured by HbA1c) than liraglutide by around 0.5%, or 5.5mmol/mol.

Semaglutide also seems to lead to fewer adverse events and side effects. So, if you’re looking for a medication to help with weight loss and manage blood sugar levels, semaglutide is the better option.

However, you must consult your doctor or local healthcare team before purchasing any medications privately. You might be able to receive a prescription for these medications if you’re eligible.

Semaglutide and liraglutide are GLP-1 receptor agonists (GLP-1s). A class of medications that have received FDA approval to support weight loss and type 2 diabetes in the U.S.

They’re now available in the UK under Wegovy, Ozempic (semaglutide), and Saxenda (liraglutide).

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What are GLP-1s?

GLP-1s are a type of medication that’s used to help with weight loss. They work by mimicking a hormone called GLP-1 that the body naturally produces after eating.

The hormone GLP-1 helps to regulate blood sugar levels by stimulating insulin production and slowing down the rate at which food leaves the stomach. It also acts on the brain to reduce appetite and support weight loss.

GLP-1 receptor agonists mimic GLP-1 and can be injected under the skin once or twice a day (liraglutide) or once a week (semaglutide), and the dose tends to increase before you reach a maintenance dose.

Semaglutide and liraglutide dosing schedules:

They may cause side effects, such as nausea, vomiting, or constipation, but these usually subside after a few weeks when your body adjusts.

Not a magic pill

These medications are designed as additional tools for weight management interventions and shouldn’t be considered lifelong medications.

Instead, they should be used to help you kickstart your weight loss journey while you commit to living a healthier lifestyle.

At Second Nature, we’ve been trusted by the NHS since 2017 to support people with type 2 diabetes and obesity to lose weight and manage their blood sugar levels and lead healthier lifestyles for the long term.

If you’re considering using semaglutide or liraglutide but need support in making positive changes to your lifestyle, Second Nature could be an option for you.

In 2022, the NHS published data in the BMJ that compared the weight loss outcomes of five providers in the National Diabetes Prevention Programme.

Second Nature was more than twice as effective at supporting weight loss than the other four providers.

Otherwise, keep reading as we dig into the science of semaglutide and liraglutide and which one is more effective for weight loss, type 2 diabetes, and their side effects.

1) Do you lose more weight on semaglutide or liraglutide?

Research suggests semaglutide supports more weight loss than liraglutide.

A meta-analysis investigated the impact of semaglutide and liraglutide and suggested that semaglutide was more effective at supporting weight loss.

Similarly, another study found that 1mg of semaglutide leads to an average of 6.5kg weight loss, compared to 3.1kg with liraglutide.

However, the studies used to compare the two drugs were from individual trials, comparing one of the medications with a placebo (a sugar pill). They hadn’t yet been compared directly with one another.

Fortunately, a randomised controlled trial was conducted in 2022 investigating the impact of once-weekly 2.4 mg semaglutide and daily 3 mg liraglutide on weight loss in individuals living with obesity. These doses were the maximum currently available and recommended.

The results showed that the 2.4mg semaglutide group participants lost 15.8% of their body weight compared to 6.4% in the 3mg liraglutide group.

Key points:

  • Semaglutide is more effective at supporting weight loss than liraglutide
  • Studies comparing individual trials investigating the drugs suggest semaglutide is at least twice as effective as liraglutide
  • A recent randomised controlled trial comparing the highest available doses of the medication showed that semaglutide was nearly three times more effective than liraglutide

2) What’s better for blood sugar, semaglutide or liraglutide?

The meta-analysis mentioned above also measured HbA1c (average blood sugar levels) and found that semaglutide was more effective at lowering HbA1c than liraglutide.

The analysis showed that 1 mg semaglutide reduced HbA1c levels by 0.56% (6 mmol/mol), 0.47% (5.2mmol/mol) and 0.3% (3.3mmol/mol) more than liraglutide 0.6 mg, 1.2 mg, and 1.8 mg.

Similarly, another study found that 1mg of semaglutide leads to an average reduction in HbA1c of 1.8%, compared to 1.3% with liraglutide.

The randomised controlled trial mentioned above investigated the impact of once-weekly 2.4 mg semaglutide and daily 3 mg liraglutide on weight loss and blood sugar in individuals living with obesity but without type 2 diabetes.

The results showed that 2.4 mg semaglutide reduced fasting plasma glucose levels by 8.3 mg/Dl compared to 4.3mg/Dl with 3mg liraglutide. Suggesting semaglutide is almost twice as effective at reducing blood sugar levels than liraglutide.

Another marker of type 2 diabetes is how much insulin is in your blood. Individuals with type 2 diabetes have insulin resistance, often displayed in high insulin levels.

This trial showed that semaglutide reduced insulin levels by 27.8% compared to 15.4% with liraglutide.

Other markers of cardiovascular health, such as blood pressure, triglycerides, and VLDL, were all reduced to a greater extent with semaglutide.

Type 2 diabetes remission

No major trials on these drugs have reported remission, defined as having two blood readings of HbA1c below 48 mmol/mol (6.5%) separated by 6 months alongside the cessation of all type 2 diabetes medication.

However, two trials have reported the percentage of participants reaching the treatment target of an HbA1c below 48 mmol/mol (6.5%) by the end of the intervention.

A randomised controlled trial comparing once-weekly 2.4 mg of semaglutide to placebo in individuals living with type 2 diabetes showed that 67.5% of participants achieved an HbA1c below 48 mmol/mol (6.5%) after 68 weeks.

Similarly, a randomised controlled trial comparing liraglutide to placebo in individuals living with type 2 diabetes found that 56.5% of participants achieved an HbA1c below 48 mmol/mol (6.5%) after 56 weeks.

The number of participants who maintained these lower blood sugar levels and put their type 2 diabetes into remission after the intervention finished is unclear.

However, these studies suggest that both medications have the potential to support type 2 diabetes remission in a significant number of individuals if they’re able to maintain their weight loss and improve their lifestyle.

Key points:

  • Semaglutide is more effective at lowering blood sugar levels in both individuals living with and without type 2 diabetes
  • However, both medications have shown that a significant number of individuals can reduce their blood sugar levels below the diagnostic threshold of type 2 diabetes
  • Although not yet proven, type 2 diabetes is plausible with the use of both medications if these individuals can maintain their changes in the long term

3) Semaglutide vs liraglutide: side effects and safety

All medications have potential side effects, some severe, some mild but uncomfortable. Individual responses to medication will vary greatly, and GLP-1s are no exception.

The most common side effects observed in GLP-1s are nausea, which seems to occur in around 10-20% of participants, and gastrointestinal (GI) symptoms, such as bloating, constipation, and cramping, which affect around 5-10% of participants.

A meta-analysis compared the impact of liraglutide and four other medications we haven’t reviewed in this guide – on weight loss and the risk of adverse effects.

The results showed that while liraglutide was more effective at supporting weight loss, you were also more likely to discontinue the medication due to the severity of the side effects and adverse events.

Interestingly, recent studies suggest that semaglutide is not only more effective at supporting weight loss, but it’s also better tolerated than liraglutide.

A randomised controlled trial was conducted in 2022 investigating the impact of semaglutide and liraglutide on weight loss in individuals living with obesity.

Semaglutide was shown to be more tolerated than liraglutide. 3.2% of participants in the semaglutide group discontinued their treatment due to side effects, compared to 12.6% with liraglutide.

Over 80% of participants in both groups reported GI-related issues such as constipation, cramping, bloating, and diarrhoea.

7.9% of participants in the semaglutide group reported severe adverse events compared to 11% with liraglutide.

All symptoms were most common when doses were increased but appeared to subside after, with milder symptoms continuing throughout the intervention. No deaths were reported in either group.

Beyond this specific trial, a rare and severe side effect of liraglutide is the development of thyroid cancer. If you have a family history of thyroid cancer, you shouldn’t take liraglutide. The relationship between semaglutide and thyroid cancer isn’t clear.

Generally, GLP-1s are well tolerated and don’t appear to cause severe adverse events in most people.

It’s important to note that it’s generally not recommended for women to take GLP-1s while they’re looking to get pregnant, are currently pregnant, or are breastfeeding.

Key points:

  • Semaglutide and liraglutide lead to side effects, most commonly nausea and GI issues such as bloating and cramping
  • Severe side effects are rare but are more common with liraglutide than semaglutide
  • Semaglutide seems to be better tolerated, and fewer people discontinue their medication due to side effects than on liraglutide
  • All medications come with risks, and you must consult your healthcare team if you’re concerned about any side effects you experience

Take home message

The recent innovations in GLP-1 medications are pretty remarkable and have caused quite a stir in the world of healthcare.

We’re in new territory where obesity and type 2 diabetes medications treat an underlying cause instead of merely treating the symptoms to support better management.

However, these drugs shouldn’t be seen as miracle cures; they’re not designed to be used for life.

They’ve been designed to be taken alongside lifestyle changes that will enable you to eventually come off the medications and maintain your lower weight for the long term.

The harsh reality is that we still don’t know the long-term effects of these medications on our health. There are examples of drugs being withdrawn from the market as more long-term data comes to light.

Lorcaserin was a weight loss drug approved by the Food and Drug Administration (FDA) in the U.S. but was recently withdrawn as data indicated that it increased cancer risk.

The example of lorcaserin is why you must weigh the pros and cons when your doctor prescribes medication or before you purchase it yourself and start treatment. Report any side effects to your healthcare team.

GLP-1s are safe and effective for most people in the short to medium term, but we don’t have long-term data to be sure they’re not causing severe adverse effects elsewhere.

At Second Nature, we’re not against using medications to support people in making healthy changes and reducing their risk of chronic disease.

However, we don’t recommend using medications as a reason not to make healthy lifestyle changes. The causes of obesity and type 2 diabetes aren’t merely rooted in biology but also in psychology and sociology.

With these medications, you may lose weight and reduce blood sugar levels. But will you be happier? Will you be more fulfilled? Will you be content with your life and social relationships?

For that, you may need to consider a lifestyle change, and if that’s something you want to commit to alongside taking GLP-1 medications, Second Nature has launched a medication-supported programme.

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