Janumet (sitagliptin/metformin) for type 2 diabetes: a patient's guide

Janumet dosages

You should discuss any concerns or questions about dosage with your prescribing physician. Janumet is available in different strengths and ratios. 

• Janumet tablets: The tablet strength indicates each tablet's amount of sitagliptin/metformin. Typical dosages may involve taking one or two tablets daily, usually with meals, to ensure optimal absorption and reduce the risk of gastrointestinal side effects. Janumet tablets come in different strengths: 

  • Janumet (sitagliptin 50 mg/metformin 500 mg)

  • Janumet (sitagliptin 50 mg/metformin 1000 mg)

  • Janumet (sitagliptin 100 mg/metformin 1000 mg)

• Janumet XR: Janumet XR is an extended-release formulation, allowing for once-daily dosing. This extended-release feature allows for a gradual release of the active ingredients throughout the day, providing a more consistent and sustained effect on blood sugar levels. The tablet strength (e.g., 100 mg/1000 mg) indicates the sitagliptin/metformin content. The usual recommendation is to take Janumet XR with your evening meal. The convenience of a once-daily regimen may make it easier to stick with the treatment. Janumet XR also comes in varying strengths: 

  • Janumet XR (sitagliptin 100 mg/metformin HCl 1000 mg)

  • Janumet XR (sitagliptin 50 mg/metformin HCl 500 mg)

  • Janumet XR (sitagliptin 50 mg/metformin HCl 1000 mg)

• Maximum dose: The maximum recommended dose of Janumet is typically determined by the healthcare provider based on the patient's response to treatment and individual factors. Always adhere to the prescribed dosage and administration instructions provided by your doctor.

• Missed dose: If you miss your dose, don’t double up on the next dose. Instead, continue with your regular dosing schedule.

• Timing: The timing of taking Janumet can depend on the specific formulation. For Janumet XR, an extended-release formulation, taking the medication with your evening meal is often recommended to ensure a consistent release of the active ingredients throughout the day. For other formulations, the general guideline is to take Janumet with meals to maximize absorption and reduce the likelihood of gastrointestinal side effects.

• Nighttime intake: While taking Janumet XR with your evening meal is recommended due to its extended-release mechanism, the timing for other formulations during the day can vary. Following your healthcare provider's instructions for the specific prescription is essential.

• Before or after food: Janumet is typically taken with meals to synchronize its effects with food intake. This helps optimize the medication's action on blood sugar levels and reduces the risk of gastrointestinal side effects.

Monitoring and follow-up

If you are prescribed sitagliptin, it is crucial to maintain regular monitoring and follow-up appointments with your doctor. These appointments are opportunities to assess the medication's effectiveness, address any concerns, and make necessary adjustments to your diabetes management plan. Your doctor will guide you on the necessary monitoring procedures, which may include:

• Blood sugar levels: Regular monitoring of blood sugar levels is fundamental in evaluating the effectiveness of sitagliptin. Your doctor may recommend specific times for checking blood sugar, and the results will inform adjustments to your treatment plan.

• Hemoglobin A1c tests: Periodic hemoglobin A1c tests provide a broader picture of your average blood sugar levels over time. These tests help assess the overall effectiveness of diabetes management, including the impact of sitagliptin.

• Kidney function tests: Sitagliptin, like other diabetes medications, may require monitoring of kidney function. Your doctor may order kidney function tests to ensure the medication is well-tolerated and does not adversely affect your kidneys.

• Follow-up appointments: These will allow for ongoing assessment of your response to sitagliptin. During these appointments, your doctor can address any side effects, discuss lifestyle factors, and make necessary adjustments to optimize your diabetes care.

• Symptom improvement: Reducing diabetes symptoms, such as excessive thirst, frequent urination, and fatigue, may indicate effective medication management.

• New or worsening symptoms: The emergence of new or worsening diabetes symptoms may prompt a reassessment of your medication regimen to ensure optimal management.

Common side effects

Janumet may come with some common mild, temporary side effects.

• Upper respiratory tract infections

• Stuffy or runny nose

• Headache

Warnings and precautions for specific patient groups

Who should not use Janumet:  

• Type 1 diabetics: You should not use Janumet if you have type 1 diabetes, as it has not been studied to show benefit or be safe for this condition. 

• History of pancreatitis: Do not take Janumet if you’ve had pancreatitis before, as it can increase the risk of repeat episodes.

• Pregnant patients: Janumet should only be used when needed, with the potential benefits justifying potential risks to the fetus. Approval from your OBGYN would be necessary before starting.

• Nursing mothers: Sitagliptin phosphate/metformin is not recommended for lactating mothers.

Caution should be used in the following when considering Janumet: 

• Elderly patients: Caution is advised when prescribing Janumet to elderly patients due to a potentially higher risk of renal impairment.

• Patients with a history of heart failure (CHF): Several types of DPP4 inhibitors other than Janumet have been associated with worsening CHF. Talk to your doctor about your history before making a shared decision about using Janumet.

• X-ray tests that use contrast agents: Janumet should be temporarily stopped before such tests and restarted only after assessing kidney function as they may temporarily impair kidney function.

• Patients with liver problems:  The medication should also be used cautiously in patients with liver problems, necessitating regular monitoring of liver function.

• Alcohol: Caution is advised when consuming alcohol with Janumet, as it can potentiate the risk of lactic acidosis.

Serious side effects

Rare but severe side effects associated with Janumet include pancreatitis, allergic reactions, kidney issues, and joint pain. Stomach pains, nausea, vomiting, and other gastrointestinal symptoms, or any other unusual or severe symptoms, should be promptly reported to your doctor for a thorough evaluation. Patients should also be alert for the rare but severe condition of lactic acidosis associated with metformin, a component of Janumet.

A severe notable side effect linked to Janumet is hypothermia, particularly when used in conjunction with specific medications, marked by a dangerously low body temperature. Patients must be attuned to symptoms like shivering, confusion, or drowsiness and seek immediate medical attention if such signs emerge. 

Additionally, cases of hypotension (low blood pressure) and resistant bradyarrhythmias (slow heart rate) have been reported, particularly in those with pre-existing cardiovascular conditions. Patients with a history of heart issues should be closely monitored, and any signs of dizziness, fainting, or irregular heart rhythms should be promptly communicated to a healthcare professional.