INS and diabetes mellitus: Finally, insulin-requiring subjects demonstrated a higher 3D-SI than diabetic subjects not taking insulin or those without diabetes (DM on insulin: 0.63 ± 0.15 vs. DM not on insulin: 0.57 ± 0.14 vs. non-DM: 0.55 ± 0.13; P = 0.001; Fig. 1).