If you've heard the term GLP-1 tossed around lately—on social media, in doctor's offices, or weight loss ads—you’re not alone. Usually, it's tied to brand names like Ozempic and Zepbound. But what is the meaning of GLP-1 as it pertains to type 2 diabetes, obesity, and metabolic health?
While touted as a "skinny shot," there's more to know about GLP-1 agonist medications before you consider if it's right for you. It helps to understand how GLP-1 medications work.
As an investigative journalist reaching middle age and fighting a battle to regain my health, I wanted to know as much as possible about an injection I might be putting into my body. Here's what I found to help you make an educated decision.
What Is GLP-1?
GLP-1 stands for glucagon-like peptide-1, a hormone your body naturally makes in the gut after you eat. It plays a key role in managing blood sugar and appetite.
The hormone tells your pancreas to release insulin, slows how fast food leaves your stomach, and sends “I’m full” signals to your brain. In other words, it helps you avoid blood sugar spikes and overeating.
People with type 2 diabetes or obesity often have impaired GLP-1 function—or their bodies don’t respond to it properly.
But here’s the thing: doctors don’t actually test your GLP-1 levels to figure this out. That’s because GLP-1 is a fast-moving hormone that changes throughout the day depending on what you eat. It’s hard to measure accurately with a standard blood test.
Instead, doctors look at the bigger picture: your blood sugar, A1C levels (which show your average blood sugar over three months), insulin resistance, body mass index (BMI), and other metabolic markers. If those numbers are off, it can suggest that your body isn’t using GLP-1 the way it should.
From that data, doctors diagnose conditions like diabetes or obesity and decide whether a GLP–1–based medication might help.
GLP-1 Terminology
For far too long I thought the name in GLP-1s was "glycogen," but it's "glucagon." Here's some hep to understand the difference in similar sounding terms.
Glucose is the basic sugar your body uses for energy. It’s what your blood sugar measures.
Glycogen is how your body stores extra glucose—kind of like a backup energy supply kept in your liver and muscles.
Glucagon is a hormone that tells your liver to break down glycogen and release glucose into your bloodstream when your blood sugar gets too low.
Also, if you're wondering what a peptide is, that's a short chain of amino acids—basically, tiny proteins. Think of them as small but powerful building blocks that help your body communicate and function. They're naturally made in the body, but synthetic peptides are also used in medicine, skincare, and supplements.
Your body uses peptides to send signals between cells, regulate hormones, support healing, and trigger specific biological responses. Some peptides act like messengers (like GLP-1), telling your body when to release insulin, grow tissue, or reduce inflammation.
Is there a GLP-2?
Yes! AS the GLP-1 name suggests, more than one glucagon-like peptide works inside our bodies.
GLP-1 helps control blood sugar and appetite, while GLP-2 focuses on keeping your gut lining healthy and supporting nutrient absorption—same hormone family, but totally different jobs.
GLP-1 helps regulate insulin, slows digestion, and reduces appetite.
GLP-2 is more involved in gut health and nutrient absorption.
GLP-2’s main job is to support gut health by helping the intestines grow, repair, and absorb nutrients. Treating low GLP-2 levels (usually with medication like Gattex) is used for rare conditions like short bowel syndrome, not for diabetes or weight management.
What Is GIP?
GIP is a hormone released by your gut when you eat, especially foods with fat or carbs. It helps your body release insulin to manage blood sugar levels, but only when glucose is present.
Unlike GLP-1, GIP doesn’t affect appetite as much—instead, it helps regulate how your body stores and uses energy.
GLP-1 and GIP work together to help your body manage blood sugar after eating. GLP-1 boosts insulin, slows digestion, and helps you feel full, while GIP also triggers insulin release and influences how your body stores fat.
What is a GLP-1 Agonist?
Now that we understand the GLP-1 meaning as a hormone, let's get into the class of drugs known as GLP-1 agonists. That's where we find options like Ozempic, Wegovy, and Zepbound.
A GLP-1 agonist is a medication that mimics the natural GLP-1 hormone in your body. The word "agonist" comes from Greek, meaning “contestant” or “actor.” In medicine, it refers to a substance that activates a receptor to produce a biological response.
So a GLP-1 agonist "acts like" the real hormone and stimulates the same effects—just longer and often stronger.
Two of the most widely discussed medications in the GLP-1 category are semaglutide and tirzepatide.
Understanding the Difference between Semaglutide and Tirzepatide
Semaglutide and tirzepatide are both injectable medications used to help manage blood sugar and support weight loss—but they work a little differently.
Semaglutide (sold under brand names like Ozempic, Wegovy, and Rybelsus) is a GLP-1 agonist, which means it mimics the GLP-1 hormone to boost insulin, slow digestion and reduce appetite.
Tirzepatide (sold as Mounjaro and Zepbound) goes a step further. It targets both GLP-1 and GIP. Because of this, tirzepatide is known as a dual agonist and shows greater weight loss results in some clinical studies.
In short, both work on GLP-1 pathways, but tirzepatide adds another hormone into the mix.
Why Choose Semaglutide if Tirzepatide Shows Better Results?
While tirzepatide may offer greater weight loss or blood sugar control in some studies, there are still a few good reasons why someone might choose semaglutide instead:
Longer track record: Semaglutide has been around longer, with more real-world data and clinical experience behind it. Some providers may feel more comfortable starting with it.
Insurance coverage: Semaglutide (especially as Ozempic) is often more widely covered by insurance, especially for diabetes. Tirzepatide may still face more hurdles or higher copays depending on the plan.
Side effect tolerance: Some people simply tolerate semaglutide better. Tirzepatide’s dual action may mean stronger results, but sometimes that also means stronger side effects.
Specific FDA approvals: Depending on a patient's health profile or insurance, one option or the other might be the only cost-effective way to get the help.
Personal or provider preference: Some people may respond better to semaglutide, or their healthcare provider may prefer to start with a single-hormone approach before stepping up to the dual agonist.
Bottom line: tirzepatide might do more on paper, but real-life choices depend on access, tolerance, insurance, and individual response. It’s not always about which is "stronger," but which is the better fit.
Understanding Your Options: Semaglutide vs. Tirzepatide
Semaglutide is sold under three brand names: Ozempic (for type 2 diabetes), Wegovy (for chronic weight management), and Rybelsus (an oral version, also for type 2 diabetes). Tirzepatide is marketed as Mounjaro for type 2 diabetes and Zepbound for weight loss.
Ozempic (semaglutide) — Approved for type 2 diabetes, this weekly injectable is what first put semaglutide on the map. It’s not technically a weight loss drug, but off-label use for that purpose helped it go viral.
Wegovy (semaglutide) —Same active ingredient as Ozempic but approved specifically for chronic weight management. Higher doses are used, and it’s become the go-to for non-diabetic patients with obesity.
Mounjaro (tirzepatide) — Developed by Eli Lilly, this drug mimics both GLP-1 and GIP, another hormone that helps with metabolism. Clinical trials showed it outperformed semaglutide for weight loss in many cases. Approved for diabetes, with weight-loss-specific versions emerging.
Zepbound (tirzepatide) — This is the weight loss–focused version of Mounjaro, approved by the FDA in late 2023. It’s made for people without diabetes who need help managing obesity.
In late 2024, Zepbound was also approved as a treatment for obstructive sleep apnea (OSA).
Drug companies run separate trials for each intended use—in this case, obesity and type 2 diabetes. So, while the medication is similar (or even identical), the approved use, recommended dose, and insurance coverage can vary depending on what the FDA has officially signed off on.
In full transparency, I only chose Zepbound because of the OSA approval. I'm just fed up with using a CPAP nightly. No, my insurance doesn't cover it, but I did manage to find the lowest price possible without coverage.
MORE: Understanding how medication patents work
Timeline of GIP and GLP-1 Discovery and Medications
1970s – GIP Discovered
GIP (originally called gastric inhibitory polypeptide) was first identified as a hormone that slowed stomach acid. Researchers later realized it plays a bigger role in insulin release after eating.
1980s – GLP-1 Identified
Scientists studying the proglucagon gene found that the gut produces GLP-1, a hormone that stimulates insulin and helps regulate blood sugar. It was officially isolated and named in the mid-to-late 1980s.
1990s – GLP-1’s Role in Appetite & Digestion Uncovered
Research expanded beyond insulin—GLP-1 was found to slow digestion, reduce appetite, and influence weight regulation. This opened the door to its use in obesity treatment.
2005 – First GLP-1 Drug Approved
Exenatide (Byetta) became the first GLP-1 receptor agonist approved by the FDA for type 2 diabetes. This marked the beginning of GLP-1–based drug development.
2012–2014 – Semaglutide Developed by Novo Nordisk
Building on earlier drugs like liraglutide (Victoza), researchers created semaglutide, a longer-lasting GLP-1 agonist with once-weekly dosing and stronger results.
2017 – FDA Approves Ozempic
Semaglutide was approved under the brand Ozempic for type 2 diabetes.
2019 – Rybelsus (Oral Semaglutide) Approved
This made semaglutide the first GLP-1 medication available in pill form.
2021 – Wegovy Approved for Weight Loss
A higher-dose version of semaglutide became the first GLP-1 drug FDA-approved for chronic weight management in people without diabetes.
2022 – Tirzepatide (Mounjaro) Approved
Eli Lilly’s tirzepatide, the first drug to target both GLP-1 and GIP receptors, was approved for type 2 diabetes.
2023 – Zepbound Approved for Weight Loss
Tirzepatide was FDA-approved under the name Zepbound for people with obesity or overweight conditions—ushering in a new era of dual-hormone weight loss treatments.
Need GLP-1 Nutrition & Fitness Help? Reach Out Today!
Legg Day Fitness is now offering GLP-1 coaching for those at any stage of the journey to lose weight or lessen the impact of diabetes using drugs like Ozempic and Zepbound. Through one-on-one or group coaching, you can reach your goals and maximize the benefits of your GLP-1 medication.
Have You Tried a GLP-1 Medication?
Yes
No, Don't Plan To
No, But Considering It
Maybe, Still Undecided
Comments