This was indicated by expression patterns that point towards specific cell–cell communications in islets of diabetes-resistant OB mice (Fig. 7a,b), which may affect downstream targets like Id4, Ltbp4 and Stat3. TGFβ1 secretion by M2-like macrophages has positive effects on beta cells via Smad signalling [56]. This evidence concerns the gene LTBP4 and diabetes mellitus.