Schwartz M W, Prigeon R L, Kahn S E, Nicolson M, Moore J, Morawiecki A, Boyko E J, Porte D
Department of Medicine, University of Washington School of Medicine, Seattle, USA.
Diabetes Care. 1997 Sep;20(9):1476-81. doi: 10.2337/diacare.20.9.1476.
Like insulin, the adipocyte hormone, leptin, circulates at levels proportionate to body adiposity. Because insulin may regulate leptin secretion, we sought to determine if plasma leptin levels are coupled to body adiposity via changes in circulating insulin levels or insulin sensitivity and whether leptin secretion from adipocytes is impaired in subjects with NIDDM.
We used multiple linear regression to analyze relationships between BMI (a measure of body adiposity) and fasting plasma levels of leptin and insulin in 98 nondiabetic human subjects (68 men/30 women) and 38 subjects with NIDDM (27 men/11 women). The insulin sensitivity index (Si) was also determined in a subset of nondiabetic subjects (n = 38).
Fasting plasma leptin concentrations were correlated to both BMI (r = 0.66, P = 0.0001) and fasting plasma insulin levels (r = 0.65, P = 0.0001) in nondiabetic men and women (r = 0.58, P = 0.0009 for BMI; r = 0.47, P = 0.01 for insulin). While the plasma leptin level was also inversely related to Si (r = -0.35; P = 0.03), this association was dependent on BMI, whereas the association between insulin and Si was not. Conversely, the relationship between plasma leptin and BMI was independent of Si, whereas that between insulin and BMI was dependent on Si. The relationship between plasma leptin levels and BMI did not differ significantly among NIDDM subjects from that observed in nondiabetic subjects.
We conclude that 1) body adiposity, sex, and the fasting insulin level are independently associated with plasma leptin level; 2) because NIDDM does not influence leptin levels, obesity associated with NIDDM is unlikely to result from impaired leptin secretion; and 3) insulin sensitivity contributes to the association between body adiposity and plasma levels of insulin, but not leptin. The mechanisms underlying the association between body adiposity and circulating levels of these two hormones, therefore, appear to be different.
与胰岛素一样，脂肪细胞激素瘦素的循环水平与身体肥胖程度成正比。由于胰岛素可能调节瘦素分泌，我们试图确定血浆瘦素水平是否通过循环胰岛素水平或胰岛素敏感性的变化与身体肥胖程度相关联，以及非胰岛素依赖型糖尿病（NIDDM）患者的脂肪细胞瘦素分泌是否受损。
我们使用多元线性回归分析了98名非糖尿病受试者（68名男性/30名女性）和38名NIDDM受试者（27名男性/11名女性）的体重指数（BMI，一种身体肥胖程度的衡量指标）与空腹血浆瘦素和胰岛素水平之间的关系。还在一部分非糖尿病受试者（n = 38）中测定了胰岛素敏感性指数（Si）。
在非糖尿病男性和女性中，空腹血浆瘦素浓度与BMI（r = 0.66，P = 0.0001）和空腹血浆胰岛素水平（r = 0.65，P = 0.0001）均相关（BMI的r = 0.58，P = 0.0009；胰岛素的r = 0.47，P = 0.01）。虽然血浆瘦素水平也与Si呈负相关（r = -0.35；P = 0.03），但这种关联依赖于BMI，而胰岛素与Si之间的关联则不依赖于BMI。相反，血浆瘦素与BMI之间的关系独立于Si，而胰岛素与BMI之间的关系则依赖于Si。NIDDM受试者中血浆瘦素水平与BMI之间的关系与非糖尿病受试者中观察到的情况没有显著差异。
我们得出以下结论：1）身体肥胖程度、性别和空腹胰岛素水平与血浆瘦素水平独立相关；2）由于NIDDM不影响瘦素水平，与NIDDM相关的肥胖不太可能是由瘦素分泌受损导致的；3）胰岛素敏感性促成了身体肥胖程度与血浆胰岛素水平之间的关联，但与瘦素无关。因此，身体肥胖程度与这两种激素循环水平之间关联的潜在机制似乎有所不同。
