What is a known possible adverse effect of DPP-4 inhibitors?

DPP-4 inhibitors, which are a class of antidiabetic medications, primarily work by increasing the levels of incretin hormones, leading to increased insulin release and decreased glucagon levels. While evaluating the possible adverse effects, it's important to understand that DPP-4 inhibitors are generally well tolerated.

C is the correct choice because hay fever-like symptoms, such as nasal congestion, runny nose, and sinusitis, have been reported with DPP-4 inhibitors like saxagliptin and linagliptin. These symptoms can arise due to the immune system's response to the medication, which makes this side effect relevant.

On the other hand, weight gain is not commonly associated with DPP-4 inhibitors; in fact, they are often weight neutral or sometimes may lead to slight weight loss. Stomach gurgling is more indicative of general gastrointestinal discomfort but is not a well-documented specific side effect of this drug class. Erectile dysfunction has not been established as a common adverse effect directly linked to DPP-4 inhibitors in clinical studies.