多次取样的静脉糖耐量试验中胰岛素分泌率的测定和计算

Estimation of insulin secretion rate in multiple sampled intravenous glucose tolerance test

目的 在体内C 肽动力学二室模型及标准参数法基础上 ,计算多次取样的静脉糖耐量试验 (FSIVGTT)中胰岛素分泌率 (ISR)。方法 15例糖耐量正常者及 11例 2型糖尿病者均行口服糖耐量试验 (OGTT)及FSIVGTT。所有标本用己糖激酶法测定葡萄糖 ,用放免法测定胰岛素 (INS)、C 肽 ,根据自编计算机程序 ,计算各时点ISR。结果 FSIVGTT中 ,对照组INS、C 肽浓度高峰出现于 4min时 ,无明显第二分泌峰 ;2型糖尿病组只有 5例于 0～ 4min时有小的分泌峰 ,曲线高峰于 6 0～ 80min。对照组ISR曲线第一分泌峰于 2min ,较INS及C 肽曲线提前 (P =0 .0 0 0 ) ,2 2min时出现第二个明显的分泌峰 ;11例 2型糖尿病者的ISR曲线均在 2～ 4min(中位数 2min)出现了小的分泌峰。结论 在用血INS及C 肽浓度作为评价 β细胞功能的指标时 ,应考虑其体内分布、清除过程的影响 ;对 2型糖尿病组 ,ISR曲线能较好地反映其第一时相INS分泌 ,在对照组 。

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 β 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.