Meneilly G S, Elahi D, Minaker K L, Sclater A L, Rowe J W
Division on Aging, Harvard Medical School, Boston, Massachusetts.
J Clin Endocrinol Metab. 1989 Mar;68(3):566-71. doi: 10.1210/jcem-68-3-566.
While normal aging is characterized by resistance to insulin-mediated glucose disposal (IMGU), the effect of age on noninsulin-mediated glucose disposal (NIMGU), which is responsible for the majority of basal glucose uptake, has not been completely evaluated. These studies were conducted on healthy nonobese young (n = 10; age, 20-30 yr) and old (n = 10; age, 62-80 yr) men. Each subject underwent two paired studies in random order. In all studies a [3H]glucose infusion was used to measure glucose uptake and production rates, and somatostatin (500 micrograms/h) was infused to suppress endogenous insulin release. In study A, plasma glucose was kept close to fasting levels (approximately 5.6 mmol/L) using an euglycemic clamp protocol for 4 h. Plasma insulin decreased to less than 20 pmol/L within 15 min and remained suppressed thereafter in all studies. Steady state (15-240 min) plasma glucagon levels were slightly greater in the elderly [young, 86 +/- 5 (+/- SE); old, 98 +/- 2 ng/L; P less than .05]. Basal glucose uptake was similar in both groups (young, 877 +/- 21; old, 901 +/- 24 mumol/min). Glucose uptake during the last hour of the study (180-240 min) was used to represent NIMGU, because insulin action was assumed to be absent by this time. NIMGU was less in the elderly (young, 744 +/- 18; old, 632 +/- 32 mumol/min; P less than 0.01). In study B, plasma glucose was kept at about 11 mmol/L for 4 h using a hyperglycemic clamp protocol. Plasma insulin decreased to less than 20 pmol/L within 15 min and remained suppressed thereafter in all studies. Steady state plasma glucagon levels were slightly but not significantly higher in the elderly (young, 88 +/- 6; old, 100 +/- 4 ng/L). Basal glucose uptake (young, 910 +/- 27; old, 883 +/- 25 mumol/min) and NIMGU (young, 933 +/- 36; old, 890 +/- 16 mumol/min; P = NS) were similar in both young and old subjects. We conclude that aging is associated with impairment in NIMGU only in the basal state, which may explain in part the increase in fasting glucose with age.
正常衰老的特征是对胰岛素介导的葡萄糖处置（IMGU）产生抵抗，然而，年龄对非胰岛素介导的葡萄糖处置（NIMGU）的影响尚未得到全面评估，而NIMGU负责大部分基础葡萄糖摄取。这些研究是在健康的非肥胖年轻男性（n = 10；年龄，20 - 30岁）和老年男性（n = 10；年龄，62 - 80岁）中进行的。每位受试者按随机顺序接受两项配对研究。在所有研究中，使用[3H]葡萄糖输注来测量葡萄糖摄取和生成速率，并输注生长抑素（500微克/小时）以抑制内源性胰岛素释放。在研究A中，采用正常血糖钳夹方案将血浆葡萄糖维持在接近空腹水平（约5.6毫摩尔/升）4小时。在所有研究中，血浆胰岛素在15分钟内降至低于20皮摩尔/升，并在此后一直保持被抑制状态。老年组的稳态（15 - 240分钟）血浆胰高血糖素水平略高（年轻组，86±5（±标准误）；老年组，98±2纳克/升；P＜0.05）。两组的基础葡萄糖摄取相似（年轻组，877±21；老年组，901±24微摩尔/分钟）。研究最后一小时（180 - 240分钟）的葡萄糖摄取用于代表NIMGU，因为此时假定胰岛素作用已不存在。老年组的NIMGU较低（年轻组，744±18；老年组，632±32微摩尔/分钟；P＜0.01）。在研究B中，采用高血糖钳夹方案将血浆葡萄糖维持在约11毫摩尔/升4小时。在所有研究中，血浆胰岛素在15分钟内降至低于20皮摩尔/升，并在此后一直保持被抑制状态。老年组的稳态血浆胰高血糖素水平略高，但无显著差异（年轻组，88±6；老年组，100±4纳克/升）。年轻和老年受试者的基础葡萄糖摄取（年轻组，910±27；老年组，883±25微摩尔/分钟）和NIMGU（年轻组，933±36；老年组，890±16微摩尔/分钟；P = 无显著差异）相似。我们得出结论，衰老仅在基础状态下与NIMGU受损有关，这可能部分解释了空腹血糖随年龄增加的现象。
