Type II diabetes is characterised by tissue resistance to insulin and is widespread in industrialised societies. A link between obesity and type II diabetes has long been suspected but details of the mechanism were unknown. Now, a newly discovered hormone described in 18 January Nature is proposed as the essential link between obesity and type II diabetes.

Michell Lazar and colleagues from University of Pennsylvania School of Medicine found that adipocytes secrete a unique signalling protein, which they call 'resistin' (for resistance to insulin). They showed that in mice bred to have both diet-induced and hereditary diabetes the resistin levels are higher than in controls. A commonly used anti-diabetic drug (rosiglitazone) reduces the resistin levels and administering an anti-resistin antibody improves blood sugar and insulin action in mice with diet-induced obesity (Nature 2001, 409:307-312). The role of resistin in normal physiology is not known.