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How long does it take for Januvia to work?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on May 11, 2023.

Official answer


Key Points

  • The effect of Januvia (generic name: sitagliptin) on your blood sugar levels may begin quickly, within the first 1 to 2 weeks. You may start to see your blood sugar drop after just a few doses.
  • However, Januvia is a drug used over the long-term for type 2 diabetes. It may take up to 24 weeks for the full therapeutic results with Januvia treatment, based on clinical studies. Most patients take medication for type 2 diabetes long-term, as there is no cure for this disease.
  • Don’t stop taking Januvia unless recommended by your doctor. If you stop taking it, your blood sugar levels will go back up.

Januvia is used in addition to diet and exercise to control blood glucose (sugar) in adults with type 2 diabetes. It is given as an oral tablet taken once daily with or without food. Your results may be different from other patients, so check with your doctor about your progress if you have a concern.

How does Januvia affect my blood sugar?

Januvia has been shown in studies that were 18 and 24 weeks long to have a beneficial effect on your blood sugar. Januvia is a drug you take on a daily basis as type 2 diabetes is a chronic (ongoing) medical condition.

A1C is a simple blood test that measures how well your blood sugar is controlled over several months. Your doctor will order these tests for you. A normal A1C level is typically below 7% for many type 2 diabetes patients, but this target number can vary and may need to be higher or lower. Ask your doctor what A1C goal is right for you.

In one study performed by the manufacturer, 229 patients with an A1C of 8.0% at the beginning of the study took Januvia 100 mg for 24 weeks.

  • At the end of the study, their A1C levels had dropped by 0.6%.
  • In patients who took an inactive placebo, their A1C levels went up by 0.2% compared to when they started the study.
  • About 36% to 41% of patients receiving Januvia had an A1C under 7% at the end of the study. Roughly 16% to 17% of patients in the inactive placebo group achieved an A1C under 7%.

When metformin was added on to Januvia treatment in 24-week studies, measures of blood sugar were also reduced.

  • The A1C was reduced by 0.7% from their starting A1C of 8.0% in those receiving Januvia + metformin; there was no change in the A1C in the placebo group.
  • About 47% of patients receiving Januvia + metformin had an A1C under 7% at the end of the study, compared to 18% in the placebo group.

How often do I take Januvia?

You will normally take Januvia once a day as directed by your doctor. You can take it in the morning or evening, but it’s best to try to take it at the same time each day.

What if I miss my Januvia dose?

If you miss a dose, take it as soon as you remember. If it’s time for your next dose, skip the medication and get back on your regular schedule. Don’t double up and take two tablets at the same time, or take one-half of a tablet. Januvia should not be cut in half or crushed.

Is Januvia safe?

Januvia is well-tolerated by most patients. However, there is always the risk for side effects with any medication. Be sure to talk to your doctor about side effects before you start treatment with Januvia.

Serious side effects with Januvia may include:

  • low blood sugar, especially when used with other medications for diabetes such as insulin or sulfonylureas drugs (such as glipizide or glimepiride)
  • pancreatitis (inflammation of the pancreas)
  • serious allergic reactions
  • heart failure
  • kidney problems, dialysis
  • severe joint pain (arthralgia)

A serious skin reaction called a bullous pemphigoid can occur with DPP-4 inhibitors such as Januvia. Call your doctor immediately if you develop blisters or the breakdown of the outer layer of your skin (erosion). You may need to stop taking Januvia.

Common side effects with Januvia (occurring in more than 5 out of every 100 patients):

  • upper respiratory tract infection
  • stuffy or runny nose
  • sore throat
  • headache

Bottom Line

  • Januvia (sitagliptin) is a type 2 diabetes medicine that can help you lower your blood sugar and reach your target goals, when used with diet and exercise.
  • Januvia works quickly to lower blood sugar, probably within the first one to two weeks. However, the full beneficial effect with Januvia may take several months, and you should continue to take it as prescribed by your doctor.
  • Most patients with type 2 diabetes take medication for the rest of their life, as there is no cure. If you stop taking Januvia, your blood sugar levels will mostly likely go back up unless your doctor has prescribed another drug regimen. Don’t stop taking Januvia unless your doctor has told you to discontinue treatment.

This is not all the information you need to know about Januvia for safe and effective use. Review the full Januvia information here, and speak to your health care provider if you have questions or concerns.


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