High-intensity breastfeeding improves insulin sensitivity during early post-partum period in obese women with gestational diabetes

Aim: To investigate whether high-intensity breastfeeding (HIB) reduces insulin resistance during early post-partum period in women with gestational diabetes (GDM), independent of post-partum weight change (PWC). Materials and methods: In this multicentre prospective study, we included Japanese women with GDM who underwent a 75-g oral glucose tolerance test (OGTT) during early post-partum. We measured plasma insulin during OGTT to obtain a homeostasis model of assessment of insulin resistance (HOMA-IR). We defined the condition in which infants were fed by breastfeeding alone or greater than or equal to 80% of the volume as HIB, and other statuses, including partial and nonbreastfeeding, as non-HIB. We investigated the association between post-partum HOMA-IR and the breastfeeding status after adjusting for confounders including PWC. Results: Among 222 women with GDM who underwent the OGTT at 7.9 ± 2.3 weeks post-partum with a PWC of −7.8 ± 3.4 kg, although the rate of abnormal glucose tolerance (prediabetes and diabetes) did not differ between the groups (33% vs 32%), the HOMA-IR in the HIB women (n = 166) was significantly lower than that in the non-HIB women (n = 56) (1.12 ± 0.85 vs 1.72 ± 1.43, P = 0.0002). The effect of the HIB was independently associated with lower HOMA-IR after adjusting for confounders including PMC. However, the subgroup analysis according to their pre-pregnancy obesity states showed that the effect was seen only in the obese subjects (BMI ≥ 25). Conclusions: In obese Japanese women with GDM, HIB has a significant effect in reducing insulin resistance during early post-partum, independent of the post-partum weight loss.