Cortisol secretion pattern in overweight/obese and normal-weight infants: a cross-sectional study.

Background The salivary circadian diurnal cortisol plays an important role in growth and development. Inappropriate levels may induce changes associated with an increased risk of obesity later in life. It is unknown if there are differences in cortisol secretion pattern between overweight/obese infants when compared with theirs peers in infancy. Thus, this study aimed to compare the salivary cortisol secretion pattern in overweight/obese and normal-weight infants. Methods Thirty-three (overweight/obese = 17 and normal weight = 16) infants between 6 and 24 months of age had saliva samples collected upon awakening (T1), 30 min after waking (T2), at 12:00 am or before the baby's meal (T3), and prior to bedtime (T4). Highly sensitive enzyme immunoassays were used for cortisol analyses. Results Salivary cortisol levels were similar between the groups: T1 (p = 0.22; 95% confidence interval [CI]: -5.65, 1.37), T2 (p = 0.24; 95% CI: -8.23, 2.17), T3 (p = 0.95; 95% CI: -3.16, 2.96), and T4 (p = 0.81; 95% CI: -1.39, 1.08); and no differences were observed between area under the curve (AUC) (p = 0.80; 95% CI: -4.58-13.66). The cortisol level reduced in T4 (95% CI: 1.35-2.96) compared to T1 (95% CI: 5.15-8.49) and T2 in the overweight/obese group (p < 0.001; 95% CI: 6.02-11.04). In the normal-weight group, the cortisol reduced in T3 (95% CI: 2.86-8.18) compared to T1 (95% CI: 5.64-12.28) and decreased until T4 (p = 0.001; 95% CI: 1.25-3.37). Conclusions The overweight/obese infant group presented a different pattern of cortisol secretion, although cortisol levels did not differ between the control group.