Bacha Fida, Saad Rola, Gungor Neslihan, Arslanian Silva A
Division of Pediatric Endocrinology, Metabolism and Diabetes Mellitus, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Diabetes Care. 2004 Feb;27(2):547-52. doi: 10.2337/diacare.27.2.547.
Adiponectin is an adipose tissue protein that enhances insulin sensitivity and has antiatherogenic properties. The present study investigated the relationship of adiponectin levels in adolescents to 1) obesity and body fat distribution and 2) insulin sensitivity and the components of syndrome X.
Twenty-three normal-weight and 26 obese adolescents had fasting adiponectin, lipid profile, and proinsulin measurements performed. Hepatic and peripheral insulin sensitivity were assessed with constant-rate [6,6-(2)H(2)]glucose infusion and a 3-h hyperinsulinemic-euglycemic clamp, respectively. Body composition was evaluated by dual-energy X-ray absorptiometry, and visceral adipose tissue (VAT) and subcutaneous adipose tissue were measured by computed tomography scan at the L(4)-L(5) level.
Obese adolescents had approximately 50% lower adiponectin than normal-weight adolescents. Moreover, obese adolescents with high (111.8 +/- 9.3 cm(2)) versus low (55.4 +/- 2.1 cm(2)) VAT had lower adiponectin levels (6.2 +/- 0.9 vs. 9.0 +/- 1.0 microg/ml, P = 0.05). Plasma adiponectin correlated positively with peripheral and hepatic insulin sensitivity (r = 0.67, P < 0.001 and r = 0.54, P < 0.001, respectively) and HDL (r = 0.52, P < 0.001) and negatively with fasting proinsulin and the proinsulin-to-insulin ratio (r = -0.64, P < 0.001 and r = -0.43, P = 0.003, respectively). In a multiple regression analysis, adiponectin, independently and together with BMI, explained 73% (R(2) = 0.73, P < 0.001) of the variance in insulin sensitivity. Adiponectin, but not adiposity, was the significant independent determinant of the proinsulin-to-insulin ratio (R(2) = 0.18, P = 0.008) and of HDL (R(2) = 0.45, P < 0.001).
In summary, hypoadiponectinemia in youth is a strong and independent correlate of insulin resistance, beta-cell dysfunction, visceral adiposity, and syndrome X. The antidiabetogenic and antiatherogenic properties of adiponectin are evident early in life and compromised in youth-onset obesity.
脂联素是一种脂肪组织蛋白，可增强胰岛素敏感性并具有抗动脉粥样硬化特性。本研究调查了青少年脂联素水平与以下两方面的关系：1）肥胖及体脂分布；2）胰岛素敏感性及X综合征的组成成分。
对23名体重正常和26名肥胖青少年进行空腹脂联素、血脂谱及胰岛素原测量。分别通过恒速[6,6-(2)H(2)]葡萄糖输注及3小时高胰岛素-正糖钳夹评估肝脏和外周胰岛素敏感性。采用双能X线吸收法评估身体成分，通过计算机断层扫描在L(4)-L(5)水平测量内脏脂肪组织（VAT）和皮下脂肪组织。
肥胖青少年的脂联素水平比体重正常青少年低约50%。此外，VAT高（111.8±9.3 cm(2)）与VAT低（55.4±2.1 cm(2)）的肥胖青少年相比，脂联素水平更低（6.2±0.9 vs. 9.0±1.0 μg/ml，P = 0.05）。血浆脂联素与外周及肝脏胰岛素敏感性呈正相关（r = 0.67，P < 0.001和r = 0.54，P < 0.001），与高密度脂蛋白（HDL）呈正相关（r = 0.52，P < 0.001），与空腹胰岛素原及胰岛素原与胰岛素比值呈负相关（r = -0.64，P < 0.001和r = -0.43，P = 0.003）。在多元回归分析中，脂联素独立或与体重指数（BMI）共同解释了胰岛素敏感性变异的73%（决定系数R(2)=0.73，P < 0.001）。脂联素而非肥胖程度是胰岛素原与胰岛素比值（R(2)=0.18，P = 0.008）及HDL（R(2)=0.45，P < 0.001）的显著独立决定因素。
总之，青少年低脂联素血症是胰岛素抵抗、β细胞功能障碍、内脏肥胖及X综合征的一个强烈且独立的相关因素。脂联素的抗糖尿病和抗动脉粥样硬化特性在生命早期就很明显，而在青少年期肥胖中会受损。
