The author, an advocate of CDT testing for insurance applicants, senses considerable uncertainty among medical directors concerning the value of the test. This review of CDT literature and the history of CDT testing in insurance laboratories is an attempt to mitigate that confusion. Two principle problems are identified: 1) the expected sensitivity of the CDT test in insurance applicants will be 50% at most, usually considerably less. 2) adapting CDT testing to commercial laboratories has been, and still is, an unsolved problem for there remains an important disparity between the method used at Clinical Reference Laboratories and LabOne. Other important issues are also reviewed: gender differences, ethnicity, LFT's and CDT, and technical facts.