INS and Hyperglycemia: In contrast, in a study of young (ages 23-25) and older (ages 64-66) adults using a hyperglycemic clamp technique, defects in beta cell function in older individuals were only observed with pre-existing impaired glucose tolerance (IGT) or Type 2 diabetes; normoglycemic older individuals had a similar insulin response to hyperglycemia as their younger counterparts [9].