by boosting GLP-1 (glucagon-like peptide-
1) it may cause the lower stomach valve to remain shut. Without Metformin
in your body, this merely leads to a feeling of fullness and upper abdominal bloat. But if you have Metformin in your system, it may lead to much worse stomach distress.
Let your doctor know if you develop something that "just does not seem right." While it may not be a Januvia side effect, your doctor should be told so he/she is able to diagnose and treat the problem.