INS and type 2 diabetes mellitus: Although metformin addresses some of the primary defects in insulin response (decreases hepatic glucose production and improves insulin sensitivity) [1,2] and is considered first-line pharmacologic treatment for type 2 diabetes [2,3], the American Diabetes Association and other guidelines recommend combination therapy when glycated hemoglobin (HbA1c) goal (<7% or ≤6.5%) [2-4] is not achieved or maintained over a 3- to 6-month period [2].