Scheen A J, Sturis J, Polonsky K S, Van Cauter E
Department of Medicine, University of Liège, Belgium.
Diabetologia. 1996 May;39(5):564-72. doi: 10.1007/BF00403303.
Normal insulin secretion includes oscillations with a period length of 80-150 min which are tightly coupled to glucose oscillations of similar period. To determine whether normal aging is associated with alterations in these ultradian oscillations, eight, modestly overweight, older men (65 +/- 5 years) and eight weight-matched young control subjects (25 +/- 4 years) were studied during 53 h of constant glucose infusion. Blood samples were collected every 20 min and insulin secretion rates were calculated by deconvolution. Ultradian oscillations of glucose and insulin secretion were evident in both groups. Pulse frequency was similar for glucose and insulin secretion, and was not affected by age. The absolute amplitude of the glucose oscillations was similar in both groups but their relative amplitude was slightly dampened in the older adults. Both the absolute and the relative amplitudes of insulin secretory oscillations were markedly reduced in the older subjects. The normal linear increase in the amplitude of insulin oscillations occurring with increasing amplitudes of glucose oscillations was still present in the older adults but analysis of covariance indicated that the slope was significantly lower than in the young control subjects (p < 0.0005), reflecting a decreased responsiveness of the beta cell to glucose changes. The temporal concordance between insulin and glucose oscillations, as estimated by pulse concomitancy and cross-correlation, was also lower in older subjects. The similarities between the alterations in the ultradian oscillations of insulin secretion and glucose in older healthy adults and those occurring in diabetic patients suggest that an impairment of beta-cell function may play a primary role in the deterioration of glucose tolerance in aging.
正常胰岛素分泌包括周期长度为80 - 150分钟的振荡，这些振荡与相似周期的葡萄糖振荡紧密耦合。为了确定正常衰老是否与这些超日振荡的改变有关，在持续葡萄糖输注53小时期间，对8名适度超重的老年男性（65±5岁）和8名体重匹配的年轻对照受试者（25±4岁）进行了研究。每20分钟采集一次血样，并通过反卷积计算胰岛素分泌率。两组均出现葡萄糖和胰岛素分泌的超日振荡。葡萄糖和胰岛素分泌的脉冲频率相似，且不受年龄影响。两组葡萄糖振荡的绝对幅度相似，但老年人中其相对幅度略有衰减。老年受试者胰岛素分泌振荡的绝对幅度和相对幅度均明显降低。随着葡萄糖振荡幅度增加，胰岛素振荡幅度正常的线性增加在老年人中仍然存在，但协方差分析表明，其斜率显著低于年轻对照受试者（p < 0.0005），这反映了β细胞对葡萄糖变化的反应性降低。通过脉冲伴随性和互相关估计，老年人中胰岛素和葡萄糖振荡之间的时间一致性也较低。健康老年人胰岛素分泌和葡萄糖超日振荡的改变与糖尿病患者的改变相似，这表明β细胞功能受损可能在衰老过程中糖耐量恶化中起主要作用。
