Insulin dynamics of breast- or formula-fed overweight and obese children.

Objective: The aim of the present study was to evaluate the association between the type of early feeding and indices of insulin metabolism in 8-year-old overweight and obese children.
Methods: The sample included 350 overweight (body mass index [BMI] ≥1.036 standard deviation score [SDS]) and obese (BMI ≥1.645 SDS) children and 33 normal-weight control subjects who had been exclusively breast-fed or formula-fed for 4 months or longer. Parameters of insulin sensitivity and secretion were derived from 120-minute oral glucose tolerance tests.
Results: Overweight and obese formula-fed children (N = 165) were more insulin resistant than breast-fed individuals (N = 185; Whole-Body Insulin Sensitivity Index 5.1 ± 2.3 vs 6.6 ± 2; p < 0.0001) despite having the same degree of obesity (BMI z-score 1.8 ± 0.4 vs 1.7 ± 0.4 SDS; p = 0.5). They compensated for enhanced insulin resistance by augmenting insulin secretion (Insulinogenic Index 6.8 ± 3.6 vs 5.2 ± 2.5 μIU/mL × mg/mL(-1); p < 0.0001). Thus, they presented with a disposition index similar to that of breast-fed children (34.6 ± 15 vs 30.8 ± 19.2; p = 0.4), Formula feeding was associated with greater catch-up growth in the first month (odds ratio 2.49, 95% confidence interval 1.97 to 3.01; p < 0.0001) and between months 6 and 12 of life (odds ratio 4.62, 95% confidence interval 3.58 to 5.67; p < 0.0001).
Conclusions: In comparison with breast-feeding, formula feeding seems to be associated with reduced insulin sensitivity and increased insulin secretion in overweight and obese children.