The correlation between the plasma insulin, and glucose concentration was studied in healthy Korean adults consisting of 20 males and 22 females of 16 to 38 years of age. The blood samples of above subjects were obtained through cubital vein at arbitrary times, during their usual working hours. Plasma insulin was assayed by means of double antibody system of radioimnmunoassy technics, and blood glucose was determined by means of Van Slyke-Folch method. Results were as follows: 1. There were no differences in the blood sugar levels in relation to the plasma insulin concentration either by sex or age. 2. In the case, when the plasma insulin concentration was within $200m{mu}D/ml$, the correlation between the insulin, and glucose concentration existed, the ratio of which was expressed as; Plasma glucose concentration(mg/dI)=$91.9+0.08{ imes}Insulin$ concentration r=0.62 3. Insulinogenic index was 12.4%, which was somewhat higher than other reports. 4. It is suggested that the correlation between plasma insulin and glucose concentration could be determined at arbitrary times instead of fasting times.