INS and type 2 diabetes mellitus: Given that pre-diabetic older adults were comparable to the normoglycemic participants also in terms of HbA1c (P=0.152), insulin (P=0.084), and HOMA (P=0.095) indexes, except for an expected greater serum glycemia (P=0.001) markedly different from T2DM patients in glycemic profiles (P<0.001 for all these traits), pre-diabetic and normoglycemic older adults were merged into a single non-diabetic group for the purpose of providing power to the analyses.