This study addressed the difficulties encountered in identifying severely insulin-resistant patients who have genetic or acquired insulin receptor dysfunction. The authors underlined the critical need for a simple and highly specific screening test for diagnosing these disorders. In this regard, they had reported previously that plasma adiponectin levels were paradoxically elevated in these receptoropathies in contrast to other forms of severe insulin resistance. They therefore sought to assess the diagnostic performance of adiponectin levels as well as insulin growth factor binding protein-1 (IGFBP-1) and sex hormone-binding globulin (SHBG), which are both insulin responsive, in 20 patients with insulin receptor mutations, 14 patients with type B insulin resistance, and 81 patients with other forms of severe insulin resistance. The authors found that adiponectin levels >7 ug/ml in severe insulin resistance had a 97% positive predictive value for insulin receptoropathy and adiponectin levels <5 ug/ml a 97% negative predictive value. Similar analyses were performed for IGFBP-1 and SHBG but neither performed as well as adiponectin. These results indicate that plasma adiponectin assessment in patients with severe insulin resistance could be a simple and inexpensive means of discriminating among patients with insulin receptoropathies. The findings also suggest that plasma IGFBP-1 and SHBG may be useful alternatives but are less accurate as diagnostic discriminators.
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