Key takeaways:
Metformin is a first-choice medication that’s been used for decades to treat Type 2 diabetes. It’s available as an immediate-release tablet, an extended-release tablet, and a liquid.
Rybelsus (semaglutide) is a newer oral Type 2 diabetes medication. In addition to lowering blood glucose (sugar), it also has body weight and cardiovascular benefits.
Your healthcare team will consider factors such as your treatment goals, health history, and risk factors when determining whether Rybelsus, metformin, or both are right for you.
Rybelsus and metformin are both available as brand-name medications. But you can also find metformin as a lower-cost generic. GoodRx can help make your prescription more affordable.
Save on related medications
If you’re living with Type 2 diabetes, there are many treatments available to help manage your blood glucose (sugar). For many people, metformin is the first medication prescribed. It’s affordable, effective, and has been a mainstay of treatment for decades.
But newer options are also available. One of them is Rybelsus (semaglutide), the pill version of the same active ingredient found in Ozempic injections.
Both Rybelsus and metformin are taken by mouth, but they work in different ways and play different roles in diabetes treatment. Here are seven key differences between Rybelsus and metformin to know about.
Good to know: Rybelsus (oral semaglutide) comes in two formulations. The original formulation (R1) continues to be sold as Rybelsus. The newer formulation (R2) is now sold under the brand name Ozempic, like the injections. For simplicity, this article refers to oral semaglutide as Rybelsus throughout.
1. Rybelsus and metformin work differently to treat Type 2 diabetes
Both Rybelsus and metformin work well for treating Type 2 diabetes. Each has been shown to lower hemoglobin A1C — a 3-month average of blood sugar levels — by a little over 1%. But they work in different ways to have this effect.
Rybelsus is a glucagon-like peptide-1 (GLP-1) receptor agonist that’s FDA approved for adults. It works by mimicking the actions of GLP-1, a gut hormone your body makes naturally. These actions help manage blood sugar levels a few different ways, including:
Stimulating your pancreas to release insulin after eating
Reducing how much sugar your liver makes
Slowing down how fast your stomach empties
Metformin is a biguanide medication that’s approved for people ages 10 and older. It works to manage blood sugar by:
Reducing how much sugar your body absorbs
Slowing your liver from making more sugar
Helping your body’s natural insulin work better to lower blood sugar
Rybelsus and metformin can work together to help lower blood sugar levels. For this reason, you may be prescribed both at the same time.
2. Rybelsus and metformin have different dosage schedules and instructions
Rybelsus and metformin are both oral medications. But there can be some differences with how often and when you take them. For example, Rybelsus is taken once daily on an empty stomach. Metformin is taken 1 to 3 times daily with meals.
When taken by mouth, semaglutide (the active ingredient in Rybelsus) isn’t absorbed very well. Because of this, you should take Rybelsus first thing in the morning on an empty stomach with no more than 4 oz of plain water. Then, wait at least 30 minutes before eating, drinking, and taking other oral medications.
Metformin comes in a few different dosage forms: immediate-release (IR) tablets, extended-release (ER) tablets, and an oral liquid. No matter the form, it’s recommended to take metformin with a meal to reduce side effects. The IR tablets and liquid are taken 1 to 3 times daily, and the ER tablets are usually taken once daily.
3. Rybelsus is also approved for its cardiovascular benefits
In addition to lowering blood sugar, Rybelsus is FDA approved to reduce the risk of major adverse cardiovascular events (MACE), which include heart attack, stroke, or cardiovascular death, among certain people with Type 2 diabetes. Metformin has long been associated with possible heart benefits, but it doesn’t have the same FDA approval as Rybelsus.
If you have heart disease or are at high risk for it, experts often recommend a GLP-1 medication like Rybelsus. During clinical trials, Rybelsus lowered the risk of MACE by 14% compared to placebo (a pill without medication) in this group.
4. Rybelsus and metformin can cause different side effects
Both Rybelsus and metformin commonly cause digestion-related side effects, such as nausea and vomiting, diarrhea, and abdominal pain. In most cases, these side effects tend to improve or go away over time. Here’s how Rybelsus and metformin side effects compare.
| Rybelsus side effects | Metformin side effects |
|---|---|
Common side effects:
Less common but serious side effects:
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Common side effects:
Less common but serious side effects:
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Rybelsus and metformin both have boxed warnings — the FDA’s strongest warning for medications. Rybelsus has a boxed warning for an increased risk of thyroid C-cell tumors because of findings from animal studies. Metformin has a boxed warning for lactic acidosis, which is when lactic acid builds up in your blood.
For this reason, certain people may be told to avoid Rybelsus or metformin. Others might require close monitoring. Your healthcare team will consider your health history and other factors when determining if Rybelsus or metformin is safe for you to take.
5. Rybelsus and metformin have different interactions to consider
Rybelsus and metformin can interact with other medications. For example, both can potentially cause your blood sugar to drop too low if they’re combined with certain other diabetes medications. But each medication also has other interactions to be aware of.
| Examples of Rybelsus interactions | Examples of metformin interactions |
|---|---|
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Make sure your prescriber and pharmacist have a current medication list to check for other possible interactions. In some cases, such as with Rybelsus, they need to adjust when you take other medications to manage potential interactions.
6. Rybelsus may be more likely to cause weight loss than metformin
If you’re living with Type 2 diabetes, weight loss might be one of your treatment goals. While it’s not approved for weight loss, Rybelsus has been shown to help people lose weight. Weight loss is also possible with metformin, though typically not as much.
As a GLP-1 receptor agonist, Rybelsus slows stomach emptying and affects areas of the brain that regulate hunger and fullness. Because of this, people taking it may feel less hungry and eat fewer calories, resulting in weight loss. Clinical trial data has shown average weight loss of up to about 10 lbs with Rybelsus, depending on the study.
Metformin, on the other hand, is generally considered weight neutral, though some people may experience modest weight loss while taking it. This is because of the way metformin works in the body. With it, your body makes less sugar and you might see small changes in appetite. These things can help with weight loss. Average weight loss with metformin is typically around 4 lbs to 6 lbs.
Some studies have shown that combining Rybelsus with metformin can lead to greater weight loss than taking metformin alone. Depending on your treatment goals, your healthcare team may recommend Rybelsus, metformin, or both.
Good to know: There are other GLP-1 medications that may provide even greater weight loss than Rybelsus, such as Ozempic and Mounjaro (tirzepatide). Semaglutide is also sold in higher doses specifically under the brand name Wegovy (pill and injection).
7. Metformin is available as lower-cost generics, while Rybelsus is brand name only
Metformin is available as a generic medication, while Rybelsus is currently available only as a brand-name product. This means metformin is usually much less expensive.
Generic metformin has been available for many years and is widely covered by insurance plans. It’s also generally affordable even if you don’t have insurance.
Rybelsus is a newer medication and doesn’t yet have lower-cost generics. Because of this, it typically costs significantly more than metformin. Most insurance plans cover Rybelsus, but prior authorization is often required. In some cases, you may need to try other medications first in a process called step therapy.
Can you take Rybelsus and metformin together?
Yes, you can take Rybelsus and metformin together. Many people with Type 2 diabetes start treatment with metformin. If additional blood sugar management is needed, your prescriber might suggest a medication like Rybelsus.
As mentioned, Rybelsus and metformin work in different ways and can have greater effects than either medication alone. This combination can help improve blood sugar levels and may also support weight loss.
In some cases, Rybelsus may be prescribed earlier in treatment, such as for people with heart disease. Your healthcare professional can help you decide whether metformin, Rybelsus, or a combination of both is the best option based on your health history and treatment goals.
How to save on Rybelsus and metformin
Rybelsus is available as a brand-name medication, and metformin comes as lower-cost generics. GoodRx can help you navigate the many ways to save on your prescription.
Save with GoodRx. GoodRx can help you save over 70% off the average retail price of the generic version of metformin. Generic metformin’s price at certain pharmacies is as low as $9.00 with a free GoodRx discount.
Save with a copay savings card. If you have commercial insurance, you may be eligible to pay as little as $25 for Rybelsus using a savings card from the manufacturer.
Frequently asked questions
Metformin isn’t typically considered “hard” on any specific organ when taken as prescribed. But it’s processed through the kidneys, so people with significantly reduced kidney function may not be able to take it safely. Your healthcare team will usually check your kidney function before starting metformin and periodically during treatment.
Anger or mood changes aren’t known to be common side effects of metformin. Most side effects involve the digestive system, such as nausea or diarrhea. That said, changes in blood sugar levels (either high or low) can sometimes affect mood or irritability.
If you notice unusual mood changes after starting metformin, talk to your healthcare professional to help determine the cause.
When taking Rybelsus, it’s important to avoid eating, drinking, or taking other medications for at least 30 minutes after your dose. This helps your body absorb the medication properly. It also helps to limit very large or fatty meals, which can worsen side effects like nausea.
Metformin isn’t typically considered “hard” on any specific organ when taken as prescribed. But it’s processed through the kidneys, so people with significantly reduced kidney function may not be able to take it safely. Your healthcare team will usually check your kidney function before starting metformin and periodically during treatment.
Anger or mood changes aren’t known to be common side effects of metformin. Most side effects involve the digestive system, such as nausea or diarrhea. That said, changes in blood sugar levels (either high or low) can sometimes affect mood or irritability.
If you notice unusual mood changes after starting metformin, talk to your healthcare professional to help determine the cause.
When taking Rybelsus, it’s important to avoid eating, drinking, or taking other medications for at least 30 minutes after your dose. This helps your body absorb the medication properly. It also helps to limit very large or fatty meals, which can worsen side effects like nausea.
The bottom line
Rybelsus (semaglutide) and metformin are both oral medications used to treat Type 2 diabetes. They work in different ways to help lower blood glucose (sugar) levels. Many people start with metformin. But Rybelsus also has body weight and cardiovascular benefits, which can make it a good option for certain people.
Talk with your healthcare team to learn more about whether Rybelsus, metformin, or both are possible treatments for you.
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References
American Diabetes Association. (2026). 10. Cardiovascular disease and risk management: Standards of Care in Diabetes—2026. Diabetes Care.
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Bu, Y., et al. (2021). Protective effects of metformin in various cardiovascular diseases: Clinical evidence and AMPK‐dependent mechanisms. Journal of Cellular and Molecular Medicine.
Kay, I. (2019). Is your mood disorder a symptom of unstable blood sugar? University of Michigan School of Public Health.
Li, Y., et al. (2024). Efficacy and safety of semaglutide combined with metformin in treating T2DM with overweight or obesity: a systematic review and meta-analysis. American Journal of Translational Research.
McGuire, D. K., et al. (2025). Oral semaglutide and cardiovascular outcomes in high-risk type 2 diabetes. The New England Journal of Medicine.
Novo Nordisk. (2026). Rybelsus (semaglutide) tablets, for oral use [package insert].
Rodbard, S., et al. (2020). Efficacy of oral semaglutide: Overview of the PIONEER clinical trial program and implications for managed care. AJMC.
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