SPP1 and Glucose intolerance: Finally, OPN deficiency protected against age-dependent VAT fibrosis (Supplemental Figure 2G) and glucose intolerance and tended to reduce insulin resistance (Supplemental Figure 2, H and I), despite higher body weight, fat mass, and adipocyte size in OPN–/– mice compared with their WT littermates (Supplemental Figure 2, J–L).