[Estimation of insulin secretion rate in multiple sampled intravenous glucose tolerance test].
OBJECTIVE
To measure and calculate insulin secretion rate(ISR) in multiple sampled intravenous glucose tolerance test (FSIVGTT) according to the two compartment model and standard parameters of the kinetics of connecting peptide (C-P) in vivo.


METHODS
15 subjects with normal glucose tolerance and 11 type 2 diabetic patients took part in the study. Oral glucose tolerance test (OGTT) and FSIVGTT were performed. Glucose concentrations were measured by hexokinase method. Insulin (INS) and C-P concentrations were measured by radioimmunoassay. A computer procedure devised by our laboratory was used to calculate the value of ISR at each time point.


RESULTS
In the control group, serum INS and C-P concentrations reached the peak at 4 min, the second peak was not obvious. In type 2 diabetes, only 5 subjects had a small peak within 4 min, two curves reached its peak between 60 and 80 min. In the control group, ISR reached its peak 2 min after injection of glucose, that was earlier than INS and C-P curves in time sequence (P = 0.000), the second obvious peak was shown at 22 min. In type 2 diabetes, an obvious but small peak of ISR was shown at 2 min and all the patients had this peak.


CONCLUSIONS
It is necessary to take the process of metabolic clearance of INS and C-P into consideration, when blood concentration of INS and C-P were used as indexes to evaluate the secretion function of beta-cells. The ISR profile is more sensitive for investigation of the second phase of insulin secretion in the control group and the first phase in type 2 diabetes group.
Ran
J
J
Endocrinology Department, Memorial Hospital, Sun Yat-Sen University of Medical Sciences, Guangzhou 510120, China.
Cheng
H
H
Li
F
F
Liu
S
S
Xiao
H
H
Chen
M
M
Huang
X
X
D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D011863:Radioimmunoassay
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin