Beta-amino tetrahydroimidazo (1, 2-a) pyrazines and tetrahydrotrioazolo (4, 3-a) pyrazines as dipeptidyl peptidase inhibitors for the treatment or prevention of diabetes

A method of treating Type 2 diabetes comprising administering to a mammalian patient in need of such treatment a therapeutically effective amount of a first compound of the formula:

• or a pharmaceutically acceptable salt thereof, and a therapeutically effective amount of a second compound selected from the group consisting of:
• (a) other dipeptidyl peptidase IV (DP-IV) inhibitors;
• (b) insulin sensitizers selected from the group consisting of (i) PPARγ agonists, other PPAR ligands, PPARα/γ dual agonists, and PPARα agonists, (ii) biguanides, and (iii) protein tyrosine phosphatase-1B (PTP-1B) inhibitors;
• (c) insulin or insulin mimetics;
• (d) sulfonylureas or other insulin secretagogues;
• (e) α-glucosidase inhibitors;
• (f) glucagon receptor agonists;
• (g) GLP-1, GLP-1 mimetics, and GLP-1 receptor agonists;
• (h) GIP, GIP mimetics, and GIP receptor agonists;
• (i) PACAP, PACAP mimetics, and PACAP receptor 3 agonists;
• (j) cholesterol lowering agents selected from the group consisting of(i) HMG-CoA reductase inhibitors, (ii) sequestrants, (iii) nicotinyl alcohol, nicotinic acid or a salt thereof, (iv) PPARα agonists, (v) PPARα/γ dual agonists, (vi) inhibitors of cholesterol absorption, (vii) acyl CoA:cholesterol acyltransferase inhibitors, and (viii) anti-oxidants;
• (k) PPARδ agonists;
• (l) antiobesity compounds;
• (m) ileal bile acid transporter inhibitors;
• and
• (n) anti-inflammatory agents.