Compounds are provided that modulate the glucagon-like peptide 1 (GLP-1) receptor, as well as methods of their synthesis, and methods of their therapeutic and/or prophylactic use. Such compounds can act as modulators or potentiators of GLP-1 receptor on their own, or with incretin peptides such as GLP-1(7-36), GLP-1(9-36), and oxyntomodulin, or with peptide-based therapies, such as exenatide and liraglutide, and have the following general structure (where “” represents either or both the R and S form of the compound): where A, B, C, R1, R2, R3, R4, R5, n, p and q are as defined herein.