Observations on the value of mass indiscriminate screening for diabetes mellitus based on a five-year follow-up

Persons screened for diabetes in 1969 by a two-hour post-Glucola capillary blood glucose determination (cutoff 140 mg./100 ml.) were retested in 1974. In matched positive/negative pairs, the relative risk for diabetes five years later was 22 times greater in the positive subjects. However, about half the 1969 positive subjects retested negative in 1974. Sixty per cent of these had had 1969 blood glucose concentrations less than 180 mg./100 ml. and 70 per cent had already failed to retest positive in 1969. In contrast, of the 1969 positive subjects who had evidence of diabetes in 1974, 60 per cent had 1969 blood glucose concentrations greater than 180 mg/100 ml. and 75 per cent had retested positive in 1969. Treatment status (diet versus medication) in 1974 of the 1969 positive subjects was related to the degree of hyperglycemia exhibited in 1969 and in 1974 as well as to the impregnation of the diagnosis into the patient by his physician. We conclude that the misassignment (intentional or unintentional) of a diagnosis of diabetes mellitus to borderline hyperglycemic individuals occurs with sufficient frequency in indiscriminate mass screening programs to question their value. Efforts now expended in such programs should be directed to targeted populations to improve individual and public benefits.