According to evaluations of islet glucose-stimulated insulin secretion, including static and perfusion systems (10, 11), oral glucose tolerance test (61, 62), HOMA-β (63), intravenous glucose tolerance test (64, 65), and euglycemic insulin clamp (66), age-dependent functional decline of human β cells has been consistently reported, separate from insulin resistance. This evidence concerns the gene INS and Insulin resistance.