What is Janumet (Sitagliptin and Metformin)?

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Last updated: April 29, 2025View editorial policy

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From the Guidelines

Janumet is a prescription medication used to treat type 2 diabetes, containing two active ingredients: sitagliptin and metformin hydrochloride, which work together to increase insulin levels and decrease glucose production in the liver. According to the most recent evidence from 1, metformin is a commonly used medication for type 2 diabetes, effective and safe, and reduces risks of microvascular complications, cardiovascular events, and death. Sitagliptin, a DPP-4 inhibitor, helps increase insulin levels after meals and decrease the amount of sugar made by the body. Janumet is typically taken twice daily with meals, and common dosages include 50/500 mg, 50/1000 mg, and 100/1000 mg (sitagliptin/metformin).

This medication is not for treating type 1 diabetes or diabetic ketoacidosis. Patients should be aware of potential side effects, including stomach upset, diarrhea, and headache, as well as the rare but serious risk of lactic acidosis, which can occur with metformin use, especially in patients with renal impairment 1. However, the risk of lactic acidosis is very rare, and metformin may be safely used in people with estimated glomerular filtration rate ≥30 mL/min/1.73 m² 1.

Key points to consider when prescribing Janumet include:

  • Monitoring renal function and adjusting the dose accordingly
  • Being aware of the potential for gastrointestinal side effects and mitigating them with gradual dose titration and/or using extended-release formulation
  • Considering the benefits of metformin in reducing cardiovascular risk and microvascular complications
  • Using Janumet as part of a comprehensive diabetes management plan that includes diet, exercise, and regular blood sugar monitoring.

From the FDA Drug Label

SITAGLIPTIN/METFORMIN 50/850MG

Janumet is a combination of sitagliptin and metformin, as indicated by the drug label 2.

  • It contains 50mg of sitagliptin and 850mg of metformin.

From the Research

Definition and Composition of Janumet

  • Janumet is a fixed-dose combination of sitagliptin and metformin HCL, manufactured by Merck Pharmaceuticals 3, 4.
  • It is used for the treatment of patients with type 2 diabetes who are inadequately controlled by sitagliptin or metformin alone or together in free-dose combination form 3.

Mechanism of Action

  • Sitagliptin, an inhibitor of the enzyme DDP-4, assists patients with type 2 diabetes mellitus to achieve glycemic control by potentiating insulin secretion and reducing glucagon secretion in a glucose-dependent manner 5.
  • Metformin, a biguanide compound, reduces glucose hepatic production and slightly improves insulin sensitivity 5.
  • The combination of sitagliptin and metformin has a complementary and possibly additive effect on glycemic control 3, 4.

Indications and Dosage

  • Janumet is indicated in the treatment of type 2 diabetes and is currently reimbursed in Belgium after failure of metformin monotherapy or the prior demonstration of the efficacy of adding sitagliptin to metformin 5.
  • The recommended dosage is 50/850 mg or 50/1,000 mg, twice daily 5.

Safety and Tolerance

  • The tolerance profile of Janumet is rather good, with digestive side effects and contraindications (risk of lactic acidosis in case of renal insufficiency) attributable to metformin 5.
  • Janumet improves glucose control without inducing hypoglycemia or weight gain 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Fixed-dose combination of sitagliptin and metformin for the treatment of type 2 diabetes.

Diabetes, metabolic syndrome and obesity : targets and therapy, 2009

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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