DPP4 and Recurrent upper respiratory tract infections: Results from pre-marketing clinical trials of DPP4 inhibitors are inconsistent with some drugs showing a potential increased dose-dependent risk of upper respiratory tract infections (e.g., sitagliptin 100 mg 11.4%, 200 mg 14.8%, placebo 7.1%) and other drugs showing no increased risk (e.g., saxagliptin)15.