A Study of the Insulin and the C-Peptide Responses to Oral Glucose Load in Nondiabetic and Diabetic Subjects

정상인(正常人) 및 당뇨병환자(糖尿病患者)에서의 경구당부하시(經口糖負荷時) 혈중(血中) Insulin과 C-Peptide의 변동(變動)

The present study was undertaken to evaluate the significance of the insulin and the C-peptide rseponse to oral glucose loads in normal and diabetic subjects and to establish the effects of the obesity. In this study, the authors have measured plasma insulin and C-peptide by means of radioimmunoassay in 10 nonobese normal, 5 obese normal, 13 nonobese moderate diabetic patients, 9 obese moderate diabetic patients and 9 severe diabetic patients. The results obtained were as follows; 1. In 10 nonobese normal subjects, the plasma insulin level at fasting state and at 30, 60, 90, and 120 min after oral glucose loads were $15.7{\pm}3.4,\;48.3{\pm}9.8,\;40.4{\pm}6.7,\;37.4{\pm}6.5\;and\;26.0{\pm}4.2uU/ml(Mean{\pm}S.E.)$ and C-peptide were $1.9{\pm}0.3,\;3.9{\pm}0.6,\;6.3{\pm}0.6,\;5.7{\pm}0.5\;and\;4.0{\pm}0.5ng/ml$. The change of C-peptide was found to go almost parallel with that of insulin and the insulin value reaches to the highest level at 30 min whereas C-peptide reaches to its peak at 60min. 2. The plasma insulin level in 5 obese normal subjects were $38.9{\pm}12.3,\;59.5{\pm}12.3,\;59.2{\pm}17.1,\;56.1{\pm}20.0\;and\;48.4{\pm}17.2uU/ml$ and the C-peptide were $5.5{\pm}0.4,\;6.8{\pm}0.5,\;7.9{\pm}0.8,\;7.9{\pm}0.8\;and\;7.8{\pm}2.0ng/ml$. The insulin response appeared to be greater than nonobese normal subjects. 3. In 13 nonobese moderate diabetic patients, the plasma insulin levels were $27.1{\pm}4.9,\;44.1{\pm}6.0,\;37.3{\pm}6.6,\;35.5{\pm}8.1\;and\;34.7{\pm}10.7uU/ml$ and the C-peptide levels were $2.7{\pm}0.4,\;4.9{\pm}0.7,\;6.5{\pm}0.5,\;7.0{\pm}0.3\;and\;6.7{\pm}1.0ng/ml$. There was little significance compared to nonobese normal groups but delayed pattern is noted. 4. In 9 obese moderated diabetic patients, the plasma insulin levels were $22.1{\pm}7.9,\;80.0{\pm}19.3,\;108.0{\pm}27.0,\;62.0{\pm}17.6\;and\;55.5{\pm}10.1uU/ml$ and the C-peptide levels were $5.2{\pm}0.4,\;8.0{\pm}1.0,\;10.4{\pm}1.6,\;10.4{\pm}1.7\;and\;10.1{\pm}1.0ng/ml$ and its response was also greater than that of nonobese moderate diabetic patients. 5. The plasma insulin concentrations in 9 severe diabetic subjects were $8.0{\pm}3.8,\;12.1{\pm}3.5,\;16.8{\pm}4.6,\;19.6{\pm}5.2\;and\;15.0{\pm}5.0uU/ml$ and the C-peptide levels were $1.6{\pm}0.3,\;2.4{\pm}0.4,\;4.1{\pm}0.6,\;4.0{\pm}0.8\;and\;4.5{\pm}0.7ng/ml$ and the insulin and C-peptide responses were markedly reduced in severe diabetic groups. 6. There were-significant differences between each groups of patients on the magnitude of total insulin or C-peptide areas, the insulinogenic index and the C-peptide index.