A retrospective review of records from hospitalized diabetic patients was undertaken to determine the concentration of serum beta-hydroxybutyrate (betaOHB) that corresponds to a HCO(3) level of 18 mEq/l, the threshold value for diagnosis in recently published consensus criteria. Simultaneous admission betaOHB and HCO(3) values were recorded from 466 encounters, 129 in children and 337 in adults.