Beta-amino heterocyclic dipeptidyl peptidase inhibitors for the treatment or prevention of diabetes

A compound of the formula I:

• wherein:
• Ar is phenyl which is unsubstituted or substituted with 1-5 of R3, wherein R3 is independently selected from the group consisting of:
• (1) halogen,
• (2) C1-6alkyl, which is linear or branched and is unsubstituted or substituted with 1-5 halogens,
• (3) OCl-6alkyl, which is linear or branched and is unsubstituted or substituted with 1-5 halogens, and
• (4) CN;
• X is selected from the group consisting of:
• (1) N, and
• (2) CR2;
• R1 and R2 are independently selected from the group consisting of:
• (1) hydrogen,
• (2) CN,
• (3) C1-10alkyl, which is linear or branched and which is unsubstituted or substituted with 1-5 halogens or phenyl, which is unsubstituted or substituted with 1-5 substituents independently selected from halogen, CN, OH, R4, OR4, NHSO2R4, SO2R4, CO2H, and CO2C1-6alkyl, wherein the CO2Cl-6alkyl is linear or branched,
• (4) phenyl which is unsubstituted or substituted with 1-5 substituents independently selected from halogen, CN, OH, R4, OR4, NHSO2R4, SO2R4, CO2H, and CO2C1-6alkyl, wherein the CO2C1-6alkyl is linear or branched, and
• (5) a 5- or 6-membered heterocycle which may be saturated or unsaturated comprising 1-4 heteroatoms independently selected from N, S and O, the heterocycle being unsubstituted or substituted with 1-3 substituents independently selected from oxo, OH, halogen, C1-6alkyl, and OC1-6alkyl, wherein the C1-6alkyl and OC1-6alkyl are linear or branched and optionally substituted with 1-5 halogens;
• R4 is C1-6alkyl, which is linear or branched and which is unsubstituted or substituted with 1-5 groups independently selected from halogen, CO2H, and CO2C1-6alkyl, wherein the CO2C1-6alkyl is linear or branched;
• and pharmaceutically acceptable salts thereof and individual diastereomers thereof.