Pham TT, Ivaska KK, Hannukainen JC, et al. - This cross-sectional and longitudinal study was undertaken to determine whether bone marrow adipose tissue (BMAT) is an insulin sensitive tissue, and if the insulin sensitivity is altered in obesity or type 2 diabetes (T2DM). The investigation was carried out in a clinical research center. For this analysis, BMAT glucose uptake was evaluated in 23 morbidly obese patients (9 with T2DM) and 9 healthy controls with normal body weight. Glucose uptake was also evaluated in another 11 controls during cold exposure. Findings suggested that insulin enhances glucose uptake in human BMAT. For obese patients with T2DM, the femoral BMAT insulin sensitivity was reduced compared with controls but improved after bariatric surgery. In addition, gene expression analysis showed that BMAT was distinct from brown and white adipose tissue. BMAT is a metabolically active, insulin sensitive and molecularly distinct fat depot that can play a role in the metabolism of whole body energy.