Pre- and Post-Pubertal Leptin Levels in Subjects Born Very Preterm and Full-Term Small for Gestational Age in Relation to Measurements of Adipose Tissue

Background: Children born with low birth weight may be at risk of developing the metabolic syndrome. Aim: Determine body composition and metabolic profile with focus on adipose tissue and leptin from childhood to young adulthood in a cohort of subjects born very preterm with LBW or term-born small for gestational age (SGA) compared to controls. Methods: This follow-up cohort study included 82 adults (57% women), mean age 21 (range 19-22) years. Seventy-four (90%) of these had taken part in a pre-pubertal study at age 9 years and were re-examined. The adult cohort comprised of subjects born very preterm (<30 gestational weeks) (n= 31) (preterm), born SGA (n=24) and full-term normal-weight controls (n= 27). Demographics including target height were collected. Adipose tissue was estimated by impedance. Fasting levels of glucose, c-peptide, leptin, insulin, insulin growth factor (IGF) binding protein (BP)-1, IGF-I and glucagon were determined. Results: Preterm women weighed less (p<0.01) and had lower height SDS (p<0.05) compared with control women at follow-up. Preterm women had lower total adipose tissue percentage (24 (20–27) vs 29 (25–32) %, p=0.037), and trunk fat mass (19 (15–23) vs 26 (22–30)%, p=0.029) compared with control women, not seen in preterm men. Glucose or insulin did not differ between groups, but mean C-peptide was higher in SGA women compared with preterm women (p<0.05). Leptin levels did not differ between groups (p=0.86). Leptin was closely correlated with total adipose content in men (r= 0.79, p< 0.001) and in women (r= 0.84, p< 0.001). Leptin adjusted for adipose tissue was higher in all preterm compared with controls (p=0.017). In multiple regression analyses, 78% of the leptin variability was explained by adipose tissue percentage, insulin and gender (p<0.0001, n=76). In preterm men IGF-I was strongly correlated with adipose tissue percentage (r=0.77, p<0.001). Conclusion: In young adulthood, preterm women weigh less, were shorter and had lower adipose tissue percentage, and all preterm had higher leptin levels adjusted for adipose tissue. We speculate that the higher leptin levels in relation to adipose tissue in preterm might serve as protection to enhance insulin sensitivity. The higher C-peptide could indicate peripheral insulin resistance in SGA women. IGF-I could be of special importance to adipose tissue in preterm men.