Substituted [1,2,4]triazolo[4,3-a]pyrazines as antidiabetics

A compound of Formula I:

• or a pharmaceutically acceptable salt or stereoisomer thereof,
• wherein:
• R1 is:
• (i) a saturated or unsaturated monocyclic aliphatic ring, wherein the ring is optionally substituted with one or more substituents independently selected from the group consisting of halogen, CN, CH3, CH2CH3, CH(CH3)2, NH(CH3), N(CH3)2, NHC(O)CH3, OH, OCH3, ═O, S(O)2CH3, S(O)2NH2, and cyclopropyl;
• (ii) a saturated or unsaturated monocyclic aliphatic ring fused with cyclopropane, wherein the ring system is optionally substituted with one or more substituents independently selected from the group consisting of halogen, CN, CH3, CH2CH3, CH(CH3)2, NH(CH3), N(CH3)2, NHC(O)CH3, OH, OCH3, ═O, S(O)2CH3, S(O)2NH2, and cyclopropyl;
• (iii) a saturated or unsaturated monocyclic aliphatic ring fused with cyclobutene, wherein the ring system is optionally substituted with one or more substituents independently selected from the group consisting of halogen, CN, CH3, CH2CH3, CH(CH3)2, NH(CH3), N(CH3)2, NHC(O)CH3, OH, OCH3, ═O, S(O)2CH3, S(O)2NH2, and cyclopropyl;
• or
• (iv) a monocyclic aromatic ring, wherein the ring is optionally substituted with one or more substituents independently selected from the group consisting of halogen, CN, CH3, CH2CH3, CH(CH3)2, NH(CH3), N(CH3)2, NHC(O)CH3, OH, OCH3, ═O, S(O)2CH3, S(O)2NH2, and cyclopropyl;
• R2 is absent, —CH2—, —(CH2)2—, —(CH2)3—, —(CH2)4—, —C(O)—, —N(R)—, —NH(CH2)n—, —S—, —S(O)—, or —S(O)2—;
• R3 is absent, —CH2—, —(CH2)2—, —(CH2)3—, —(CH2)4—, —N(R)—, —NH(CH2)n—, —S—, —S(O)—, or —S(O)2—;
• each R is independently H, CH3, or CH2CH3;
• each n is independently 1, 2, 3, or 4;
• and
• n1 is 1 or 2.