Liu Juan, Li Yan-bing, Shao Hong, Li Yue-xia, Yuan Yong-hong, Xiao Yi-Bin, Weng Jian-ping
Department of Endocrinology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.
Zhonghua Yi Xue Za Zhi. 2007 May 15;87(18):1252-5.
To investigate the function of islet beta cells in subjects with normal glucose tolerance (NGT), impaired glucose regulation (IGR), and type 2 diabetes mellitus (T2DM). Different indexes of insulin secretion, including DeltaI30/DeltaG30, AIR or HOMAbeta, were compared.
178 subjects without overt diabetes were classified into three groups according to the results of 75 g oral glucose tolerance test (OGTT): NGT group (n = 68), IGR group (n = 75), and T2DM group (n = 35). Intravenous glucose tolerance test (IVGTT) was carried out 1 approximately 3 days later in all participants, with measurement of plasma insulin. The ratio of insulin-to-glucose levels increment during the first 30 min of OGTT (DeltaI30/DeltaG30) and the acute insulin response (AIR) in IVGTT were used as indexes of early insulin secretion. Homeostasis model assessment of insulin secretion (HOMAbeta) was another indicator of insulin secretion. The fasting plasma proinsulin level (FPI) was measured and the ratio fasting proinsulin to fasting insulin (PI/I) was calculated. HOMA insulin resistance index (HOMA IR) was used to assess the insulin resistance.
The DeltaI30/DeltaG30 and AIR of the IGR group, adjusted by age, sex, and BMI, were both significantly lower than those of the NGT group. But the HOMAbeta of the IGR group was only slightly lower than that of the NGT group. Compared with the NGT subjects, the T2DM patients had a very severe islet beta cell dysfunction (84% decrease in AIR, 70% decrease in DeltaI30/DeltaG30 and 62% decrease in HOMA beta). When the DeltaI30/DeltaG30 was adjusted by HOMR IR, the extent of impairment in early insulin response was similar to that of AIR (87% versus 84% lower than that of the NGT group). The FPI and ratio of proinsulin to insulin were higher in the T2DM subjects compared with the NGT subjects (24.4 pmol/L +/- 18.0 pmol/L vs 10.9 pmol/L +/- 6.7 pmol/L; and 14.7% +/- 10.5% vs. 10.0% +/- 6.5%, both P < 0.05). There was a significantly positive correlation between DeltaI30/DeltaG30 and AIR (r = 0.75, P < 0.001).
In the stage of IGR, an evident deficit in phasic insulin secretion after glucose load and a decreasing HOMAbeta are exhibited. In addition to this, qualitative decrease of insulin secretion appears in the DM stage. AIR is a reliable index of isletbeta cell function. DeltaI30/DeltaG30 is an alternative one in the subjects with NGT and IGR. But it should be adjusted by IR in diabetic patients.
研究糖耐量正常（NGT）、糖调节受损（IGR）和2型糖尿病（T2DM）患者胰岛β细胞的功能。比较胰岛素分泌的不同指标，包括DeltaI30/DeltaG30、急性胰岛素反应（AIR）或稳态模型评估胰岛素分泌指数（HOMAbeta）。
根据75g口服葡萄糖耐量试验（OGTT）结果，将178例无明显糖尿病的受试者分为三组：NGT组（n = 68）、IGR组（n = 75）和T2DM组（n = 35）。所有参与者在大约1至3天后进行静脉葡萄糖耐量试验（IVGTT），并测定血浆胰岛素。将OGTT前30分钟内胰岛素与葡萄糖水平的增量比值（DeltaI30/DeltaG30）和IVGTT中的急性胰岛素反应（AIR）作为早期胰岛素分泌指标。胰岛素分泌的稳态模型评估（HOMAbeta）是另一个胰岛素分泌指标。测量空腹血浆胰岛素原水平（FPI）并计算空腹胰岛素原与空腹胰岛素的比值（PI/I）。采用稳态模型评估胰岛素抵抗指数（HOMA IR）评估胰岛素抵抗。
经年龄、性别和体重指数校正后，IGR组的DeltaI30/DeltaG30和AIR均显著低于NGT组。但IGR组的HOMAbeta仅略低于NGT组。与NGT受试者相比，T2DM患者存在非常严重的胰岛β细胞功能障碍（AIR降低84%，DeltaI30/DeltaG30降低70%，HOMA beta降低62%）。当DeltaI30/DeltaG30经HOMA IR校正后，早期胰岛素反应的受损程度与AIR相似（比NGT组低87%对84%）。与NGT受试者相比，T2DM受试者的FPI和胰岛素原与胰岛素的比值更高（24.4 pmol/L±18.0 pmol/L对10.9 pmol/L±6.7 pmol/L；以及14.7%±10.5%对10.0%±6.5%，均P<0.05）。DeltaI30/DeltaG30与AIR之间存在显著正相关（r = 0.75，P<0.001）。
在IGR阶段，葡萄糖负荷后胰岛素的阶段性分泌明显不足，HOMAbeta降低。除此之外，在糖尿病阶段胰岛素分泌出现质的下降。AIR是胰岛β细胞功能的可靠指标。DeltaI30/DeltaG30是NGT和IGR受试者的替代指标。但在糖尿病患者中应经胰岛素抵抗校正。
