Reproducibility of the Oral Glucose Tolerance Test

Results are presented of a study undertaken to explore the reproducibility of the 100 gm. oral glucose tolerance test. Over 400 male volunteers from an institutional population, who were not known to be diabetic, participated in a program which included a series of six tests for each individual over a period of one year. Ten men were tested daily, and each retested at intervals of approximately two months. Bloods were drawnat fasting, one, two and three hours after the administration of a 100-gm. glucose drinkand duplicate determinations were obtained on the Auto- Analyzer. Average blood glucose levels for the total group remained stable over time. However, blood glucose levels for individuals varied considerably. On single tests, some of the men exhibited borderline or diagnostic test readings, but in no case was this consistent over all tests. Some of the factors which contribute to individual variance are considered briefly. Implications of the data on interpretation of the results of oral glucose tolerance tests are presented.