The effect of high-intensity breastfeeding on postpartum glucose tolerance in women with recent gestational diabetes

BACKGROUND Although breastfeeding is expected to reduce the incidence of diabetes in women with gestational diabetes, the effect has not been clearly confirmed. We examined whether or not high-intensity breastfeeding reduces the incidence of abnormal glucose tolerance and investigated the effect of high-intensity breastfeeding on insulin resistance during the first year postpartum in Japanese women with current gestational diabetes. METHODS In this retrospective study, we included women with gestational diabetes who underwent postpartum 75 g oral glucose tolerance test during the first year (12-14 months) postpartum from 2009 to 2011 at a single tertiary perinatal care center in Japan. High-intensity breastfeeding was defined as the condition in which infants were fed by breastfeeding alone or 80% or more of the volume. We investigated the effect of high-intensity breastfeeding on the prevalence of postpartum abnormal glucose tolerance and the postpartum homeostasis model of assessment of insulin resistance (HOMA-IR), after controlling for confounders, including prepregnancy obesity and weight changes during pregnancy and postpartum. RESULTS Among 88 women with gestational diabetes, 46 (52%) had abnormal glucose tolerance during the postpartum period. High-intensity breastfeeding women (n = 70) were significantly less likely to have abnormal glucose tolerance than non-high-intensity breastfeeding women (n = 18) (46% vs. 78%, p = 0.015). High-intensity breastfeeding was also associated with a lower HOMA-IR at 12-14 months postpartum than non-high-intensity breastfeeding (1.41 ± 1.02 vs. 2.28 ± 1.05, p = 0.035). Those associations remained significant after controlling for confounders. At least six months of high-intensity breastfeeding had a significant effect on lowering both the abnormal glucose tolerance prevalence and HOMA-IR compared with non-high-intensity breastfeeding. CONCLUSIONS In Japanese women with gestational diabetes, high-intensity breastfeeding ≥6 months had a protective effect against the development of abnormal glucose tolerance during the first year postpartum through improving insulin resistance, independent of obesity and postpartum weight change.