Low serum adiponectin levels in subjects born small for gestational age: impact on insulin sensitivity

Increasing evidence point to the role of the adipose tissue on the insulin resistance associated with reduced fetal growth. Since adiponectin, exclusively produced by the adipose tissue, exerts an important insulin-sensitizing activity, it appears critical to investigate the effect of being born small for gestational age (SGA) on adiponectin production in adulthood and its relationship with insulin sensitivity.

Serum adiponectin concentrations were measured in 486 young adults born SGA, precisely selected on birth data, who were compared to 573 age-matched subjects born appropriate for gestational age (AGA). The relationship between serum adiponectin levels and insulin-resistance indices measured under OGTT were tested and compared between the two groups.

The SGA group demonstrated significantly reduced serum adiponectin levels than controls (12.6 +/- 6.9 vs 13.2 +/- 6.4 microg/ml, P = 0.02) and the difference remained significant when the key regulatory factors were taken into account (P = 0.008). In the AGA group, fasting I/G taken as an insulin-resistance index negatively correlated with serum adiponectin concentrations (P = 0.02), while the relationship followed a U-shape with increased fasting I/G ratio despite high concentrations of serum adiponectin in the SGA group (P = 0.12).

Subjects born SGA demonstrated significantly reduced serum adiponectin levels, which were not related to insulin-resistance indices in comparison to what observed in age-matched subjects born AGA. Although this defect in adiponectin production and in its insulin-sensitizing action remains to be elucidated at the molecular level, it strengthens the critical contribution of the adipose tissue in the metabolic complications associated with reduced fetal growth.