High lactation index is associated with insulin sensitivity

The aim of the study was to evaluate the contribution of lactation to insulin sensitivity in women 12 to 18 month postpartum using an oral glucose tolerance test (OGTT). Mean lactation index (LI), a scoring system that considers the establishment and maintenance of the lactation was used. Lactation index was calculated according to the number of months of breast-feeding per child with a maximum of 72 points. The mean LI was calculated by dividing the total number of points by the number of children. A cutoff point of 72 was considered for the LI. We investigated the inverse of the homeostasis model assessment (HOMA(Sens)) and the Cederholm index. Healthy women went through standardized interview and anthropometry. After a 10- to 12-h overnight fast, a 2-h OGTT was performed. Multiple regression analysis was performed with HOMA(Sens) and Cederholm index, which were adjusted for parity, percentage body fat, LI and presence/absence of breast-feeding. Both HOMA(Sens) and Cederholm index were negatively associated with percentage body fat (P<.01), and Cederholm index was positively associated with LI (P=.01). Mean 120-min insulin levels were significantly lower in women with LI=72 when compared with LI<72 women. Insulin sensitivity measured by the Cederholm index is positively associated with prolonged and sustained lactation, while percentage body fat presented a negative association. In this way, sustained lactation-associated metabolic changes are considered protective to women's health.