Brief Answer:
Different drugs but same class of drug, both effective.

Detailed Answer:
Hello and welcome,

Onglyza is saxagliptin and Januvia is sitagliptin. So they are different medications but in the same class.

There aren't a lot of articles to compare them, but I did find one medical article on their use in diabetes 2 stating the following:

"Abstract
Sitagliptin and saxagliptin are oral hypoglycemic agents inhibitors of DPP-4, indicated in the treatment of type 2 diabetes mellitus in combination with metformin, in patients who have not achieved adequate glycemic control. In our study we enrolled 128 decompensated type 2 diabetes patients while on metformin maximum dosage. In both sitagliptin and saxagliptin groups we observed a significant reduction in fasting glucose, glycated hemoglobin, weighing, BMI, triglycerides, while the reduction in total cholesterol, LDL cholesterol did not reach statistical significance. There was no suspension of therapy, adverse events appeared minor and temporary. In conclusion, our observations highlight the almost identical efficacy of sitagliptin and saxagliptin."

So it appears that their actions and effectiveness are very similar, even if they are not identical medications.

I hope this information helps. Please let me know if I can provide further information or clarification.

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