Sitagliptin (Januvia) and Metformin: When Do You Need Both

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If you're living with Type 2 diabetes, there's a good chance you're taking metformin to help keep your blood glucose (sugar) within a healthy range. Metformin is effective and has been recommended as a first-choice medication by experts for many years. But for many people, taking metformin by itself doesn't help lower glucose levels enough.

When this happens, prescribers may suggest taking a second medication. One popular "add-on" medication choice is sitagliptin (Januvia). This oral medication can give people greater glucose reduction, helping them to reach their health goals.

But how do sitagliptin and metformin work together to manage Type 2 diabetes? And are there risks with the combination?

How do sitagliptin and metformin work?

Sitagliptin and metformin both help lower blood glucose and hemoglobin A1C (HbA1c or A1C). Your A1C represents your average glucose levels over the past 2 to 3 months. But each medication works in different ways.

Sitagliptin is a dipeptidyl peptidase-4 inhibitor (DPP-4 or "gliptin" for short). It works by blocking the DPP-4 enzyme (protein). This helps raise natural levels of gut hormones, such as glucagon-like peptide-1 (GLP-1), that help regulate digestion. With more GLP-1 in the body, the pancreas releases more insulin when you eat and the liver makes less glucose. Over time, this lowers your blood glucose and A1C levels.

Metformin is a biguanide medication. It works in three main ways to help lower glucose:

• It makes your body more sensitive to its natural insulin.

• It lowers the amount of glucose you absorb from your intestines after eating.

• It decreases the amount of glucose that your liver makes.

Why are sitagliptin and metformin sometimes prescribed together?

Prescribers may recommend adding sitagliptin if metformin isn't lowering your A1C enough but you're very close to your target range. On average, sitagliptin reduces A1C by up to 0.8%. So it could give you the extra push you need to meet your goal.

Experts often recommend starting metformin shortly after you've been diagnosed with Type 2 diabetes. Metformin on its own, can reduce A1C by up to 2%. After several months of taking it, your prescriber should recheck your A1C levels to see how it's working for you. If your levels aren't within your goal on your dosage of metformin, your prescriber may decide to prescribe a second medication.

There are many choices when it comes to oral diabetes medications. Deciding which diabetes medication you should add to metformin is an individualized choice. Your prescriber will consider multiple factors, such as your current A1C, body mass index (BMI), other health conditions, and risk for low blood glucose (hypoglycemia). They should also consider your insurance coverage and medication costs.

Sitagliptin is one possible option that's safe to combine with metformin. Sitagliptin can be a possible choice to add to metformin if you're close to reaching your target A1C and just need a little more support to reach your goal. But there's no single diabetes treatment regimen that's best for everyone. So don't be surprised if your medications are different from a friend or family member who has Type 2 diabetes.

Can you take sitagliptin without metformin?

Most people take sitagliptin with metformin. It's not common for people to take it by itself. As mentioned above, metformin is a common first-choice diabetes medication and is a key part of most people's regimens.

But there are some cases when you may not be able to take metformin, like if you're allergic to it or you have severe kidney disease. In these cases, people may take add-on medications alone. While sitagliptin is generally safe when taken by itself, it's not as effective as other metformin alternatives. These other options provide greater A1C reduction than sitagliptin.

How are sitagliptin and metformin taken?

Sitagliptin is an oral tablet. It's recommended to take it by mouth once a day with or without food. You can take sitagliptin at any time of the day, but it's best to take it around the same time each day. Most people take the 100 mg dose. But people with kidney problems may need to take a lower 25 mg or 50 mg dose.

Metformin is available as an oral tablet and liquid. The tablets come in immediate-release (IR) or extended-release (ER) forms. Most people take metformin IR once or twice a day. It's recommended to take metformin ER once a day with your evening meal. Both metformin IR and ER should be taken with food to help prevent upsetting your stomach (a common side effect). People usually start metformin at 500 mg and slowly increase their dose over time to minimize stomach irritation.

It can be difficult to remember to take multiple pills at different times throughout the day. To help with this, sitagliptin and metformin are also available in one combined pill. It comes as a twice-daily IR tablet (Janumet) and a once-daily ER tablet (Janumet XR). Both forms should be taken with food.

This combination pill can be a convenient option to help lower the number of pills you take in a day. One downside, however, is that the pill comes in fixed doses, which can make adjusting your dosage more difficult.

Can you lose weight on sitagliptin and metformin?

Don't expect to see significant weight loss while taking sitagliptin or metformin. Sitagliptin is considered "weight neutral," meaning that most people don't lose or gain body weight while taking it. Metformin is mostly considered weight neutral as well. But some people may lose a modest amount of weight while taking it.

If you're considered overweight or obese, even losing a small amount (3% to 7%) of body weight can help improve your blood glucose. But medications shouldn't be the only method for helping you to lose weight. Combining them with a diabetes-friendly diet and regular exercise is recommended for both glucose balance and weight management.

Are there any specific risks with taking sitagliptin and metformin together?

It's safe for most people to take sitagliptin and metformin together. But keep in mind that each medication comes with its own side effects. And even if two medications are safe to combine, you might still experience side effects from one or both.

Sitagliptin's most common side effects are mild cold symptoms and headache. It can also increase your risk of hypoglycemia if you take it with insulin or sulfonylureas such as glipizide (Glucotrol XL). Very rare but serious sitagliptin side effects include pancreatitis (swelling of the pancreas), new or worsening heart failure, and kidney problems.

Metformin's most common side effects are diarrhea, nausea, and vomiting. Taking metformin with food can help reduce these common side effects. And they tend to get better or resolve over time. Metformin carries a risk for a very rare side effect called lactic acidosis. People with certain health conditions, such as severe kidney disease, may have a higher risk for this side effect.

Before starting either medication, your prescriber will likely check your kidney health. If you have kidney disease, you may need to take a lower dosage of sitagliptin, metformin, or both. Be sure to provide your prescriber and pharmacist with a full list of your medications. This can help your healthcare team screen for and prevent potential interactions.

How to save on sitagliptin and metformin

Sitagliptin and certain forms of metformin are available as brand-name medications. But you can also find them as lower-cost generics. The combination pill is currently only available as a brand-name medication. GoodRx can help you navigate the ways to save on your prescription.

• Save on metformin. 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 $4.00with a free GoodRx discount.

• Save on generic sitagliptin. Sitagliptin's manufacturer offers the medication for $80 per month when purchased through a certain pharmacy. GoodRx can help you access these savings and transfer your prescription if needed.

• Save on Januvia. If you have commercial insurance, you may be eligible to pay as little as $5 for Januvia using a savings card from the manufacturer. If you're uninsured or underinsured, you may be eligible for Januvia's patient assistance program, which offers the medication free of cost.

• Save on Janumet. If you have commercial insurance, you may be eligible to pay as little as $5 per month for Janumet or Janumet XR using a savings card from the manufacturer. If you're uninsured or underinsured, you may be eligible for Janumet's patient assistance program, which offers the medication free of cost.

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