RADIOIMMUNOASSAY MAY OVERESTIMATE INSULIN IN NON-INSULIN-DEPENDENT DIABETICS

We have compared insulin concentrations measured by radioimmunoassay (RIA) in plasma from 50 fasting non‐insulin‐dependent diabetics (NIDDM) with those measured by a new monoclonal antibody‐based two‐site immunoradiometric assay (IRMA) of insulin (which has no significant cross‐reaction with proinsulin‐like molecules). We find that the RIA measures the sum of the insulin and proinsulin like molecules and that the IRMA insulin concentrations are 38% of those measured by the RIA in those diabetic subjects. We conclude that the importance of insulin deficiency in NIDDM may have been obscured by this error. Copyright © 1990, Wiley Blackwell. All rights reserved