There are many advantages of combining incretin therapy [glucagon-like peptide-1 
(GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors] with 
insulin therapy as a glucose-lowering strategy in type 2 diabetes. One important 
advantage is the complementary mode of the mechanistic action of incretin and 
insulin therapy. Another advantage is the reduction in risk of hypoglycemia and 
weight gain when adding incretin therapy to insulin. Several clinical trials 
have studied the addition of GLP-1 receptor agonists [exenatide BID (twice 
daily), lixisenatide, albiglutide] or DPP-4 inhibitors (vildagliptin, 
sitagliptin, saxagliptin, alogliptin, linagliptin) to ongoing insulin therapy or 
adding insulin to ongoing therapy with a GLP-1 receptor agonist (liraglutide). 
These studies show improved glycemia in the presence of limited risk for 
hypoglycemia and weight gain with the combination of incretin therapy with 
insulin. This article reviews the background and clinical studies on this 
combination.