From the Guidelines
Janumet is a combination medication containing sitagliptin and metformin that is used to treat type 2 diabetes mellitus, and it is typically prescribed when diet and exercise alone are not enough to control blood sugar, or when patients need both medications and would benefit from taking them as a single pill. It works by helping to control blood sugar levels through two different mechanisms: sitagliptin is a DPP-4 inhibitor that increases insulin release and decreases glucagon secretion, while metformin reduces glucose production in the liver and improves insulin sensitivity in the body's tissues.
- Janumet is not suitable for treating type 1 diabetes or diabetic ketoacidosis.
- Patients should be aware that metformin carries a rare risk of lactic acidosis, particularly in those with kidney problems, and regular kidney function monitoring is necessary while taking this medication, as stated in the 2025 standards of care in diabetes 1.
- Common side effects may include stomach upset, diarrhea, and upper respiratory infections.
- The choice of medication added to metformin is based on the clinical characteristics of the patient and their preferences, including the presence of established ASCVD or indicators of high ASCVD risk, other comorbidities, and risk for specific adverse drug effects, as well as safety, tolerability, and cost, as recommended in the 2021 standards of medical care in diabetes 1.
- A patient-centered approach should be used to guide choice of pharmacological agents, considering patient preferences, cost, and potential side effects of each class, effects on body weight, and hypoglycemia risk, as emphasized in the 2014 standards of medical care in diabetes 1.
From the Research
Janumet Overview
- Janumet is a fixed-dose combination of sitagliptin and metformin, used to treat type 2 diabetes 2, 3.
- Sitagliptin is a specific inhibitor of dipeptidylpeptidase-4, which blocks the rapid degradation of incretin hormones, resulting in a potentiation of insulin secretion and reduction of glucagon secretion in a glucose-dependent manner 2, 4.
- Metformin is a biguanide compound that reduces glucose hepatic production and slightly improves insulin sensitivity 2.
Indications and Usage
- Janumet is indicated in the treatment of type 2 diabetes, particularly in patients who are not adequately controlled by taking either sitagliptin or metformin alone, or for patients who are currently taking both simultaneously 3.
- It is also used as an initial combination therapy, usually with fixed-dose combinations of sitagliptin/metformin, or as add-on therapy to metformin or to other antihyperglycaemic drugs, with or without metformin 5.
Pharmacokinetics and Bioequivalence
- A study compared the bioequivalence of sitagliptin and metformin HCl extended-release tablets versus Janumet XR in healthy volunteers under fasting and fed conditions, and found that the test drug was bioequivalent to the reference drug 6.
- The study demonstrated that sitagliptin 100 mg and metformin 1000 mg produced by Nanjing Chia-Tai Tianqing Pharmaceutical Company was bioequivalent to the branded Janumet XR, and both drugs were well tolerated 6.
Efficacy and Safety
- Janumet has been shown to improve glucose control without inducing hypoglycaemia or weight gain 2, 3.
- Sitagliptin has been shown to be safe and effective at 100 mg daily doses, and when given in combination with metformin, the effect on glycemic control is thought to be complementary and possibly additive 3, 5.
- The tolerance profile of Janumet is rather good, with digestive side effects and contraindications attributable to metformin 2.