Insulin Resistance, Acanthosis Nigricans, And Polycystic Ovaries Associated With A Circulating Inhibitor Of Postbinding Insulin Action

A 21-year-old woman with polycystic ovary syndrome, hirsutism, and acanthosis nigricans exhibited insulin resistance despite normal insulin binding, due to a circulating low molecular weight inhibitor affecting postbinding insulin action. Her serum inhibited insulin-stimulated lipogenesis in rat fat cells more than control serum. Treatment with clomiphene improved her symptoms and reduced serum inhibitory activity. The inhibitor was stable under various conditions and appeared to be a low molecular weight substance loosely bound to a higher molecular weight component. This suggested that her insulin resistance was linked to this circulating inhibitor.