Pisu E, Diana A, Lombardi A, Cassader M, Pagano G
Acta Diabetol Lat. 1980 Apr-Jun;17(2):153-60. doi: 10.1007/BF02580997.
Glucose tolerance tends to decrease in healthy aged subjects without family history of diabetes. Either reduced insulin secretion or insulin resistance may be responsible. Insulin secretion and insulin sensitivity were studied in 7 aged subjects (68-75 years) and 8 young controls (21-27 years). A 1-mg i.v. glucagon and a 5-U/m2 body area i.v. insulin test were run in each subject at 07(00) and at 19(00) on two different days to detect diurnal variations. An arginine test was also performed to evaluate pancreatic glucagon behavior. In the evening, young subjects presented a glucose tolerance impairment with significantly decreased plasma insulin levels, and a reduced hypoglycemic effect of exogenous insulin. Resistance to both endogenous and exogenous insulin in the aged was observed in the morning without significant morning/evening variations. Since the response to contra-insular hormones (GH in the insulin test, glucagon in the arginine test) was the same in both age groups, their role in the phenomenon could be ruled out. It is suggested that in the aged a stable reduction in number and/or a change in affinity of insulin receptors may occur. In addition, since aging is seen to be associated with the disappearance of diurnal variations in glucose tolerance and insulin secretion and sensitivity, and since a reduction in the receptor level of young healthy subjects in the evening has been reported by some authors, it is suggested that aged subjects may be less able to modulate the binding of insulin to its peripheral receptors in the course of the day.
在无糖尿病家族史的健康老年受试者中，葡萄糖耐量往往会降低。这可能是由于胰岛素分泌减少或胰岛素抵抗所致。对7名老年受试者（68 - 75岁）和8名年轻对照者（21 - 27岁）的胰岛素分泌和胰岛素敏感性进行了研究。在两个不同的日子里，于上午7（00）和晚上19（00）对每位受试者进行了1毫克静脉注射胰高血糖素和每平方米体表面积5单位静脉注射胰岛素试验，以检测昼夜变化。还进行了精氨酸试验以评估胰腺胰高血糖素的行为。晚上，年轻受试者出现葡萄糖耐量受损，血浆胰岛素水平显著降低，外源性胰岛素的降血糖作用减弱。在早晨观察到老年人对内源性和外源性胰岛素均有抵抗，且早晚无明显差异。由于两个年龄组对对抗胰岛素激素（胰岛素试验中的生长激素、精氨酸试验中的胰高血糖素）的反应相同，因此可以排除它们在该现象中的作用。提示老年人可能出现胰岛素受体数量稳定减少和/或亲和力改变。此外，由于衰老与葡萄糖耐量、胰岛素分泌及敏感性的昼夜变化消失有关，且有作者报道年轻健康受试者在晚上受体水平降低，因此提示老年受试者在一天中可能较难调节胰岛素与其外周受体的结合。
