The association of breastfeeding with insulin resistance at 17 years: Prospective observations from Hong Kong's "Children of 1997" birth cohort.

Breastfeeding has many benefits for mother and infant. Whether breastfeeding also protects against type 2 diabetes is unclear. To clarify the role of breastfeeding in type 2 diabetes, we assessed the association of breastfeeding with insulin resistance in late adolescence in a birth cohort from a non-Western setting where breastfeeding was not associated with higher socio-economic position. We used multivariable linear regression, with multiple imputation and inverse probability weighting, to examine the adjusted associations of contemporaneously reported feeding in the first 3 months of life (exclusively breastfed, mixed feeding, or always formula-fed) with fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) at 17 years in a subset (n = 710, 8.6% of entire cohort) of the Hong Kong Chinese birth cohort "Children of 1997." We found a graded association of breastfeeding exclusivity in the first 3 months of life with lower fasting insulin and HOMA-IR (p-for-trend < .05), but not fasting glucose, at 17 years. Exclusively breastfed adolescents (7%) had nonsignificantly lowest fasting insulin and HOMA-IR, adjusted for sex, birth weight, parity, length of gestation, pregnancy characteristics, parents' education, and mother's place of birth. Exclusively breastfeeding for 3 months may be causally associated with lower insulin resistance in late adolescence. Further follow-up studies into adulthood are required to clarify the long-term protection of breastfeeding from type 2 diabetes.