A new study published in Clinical Nutrition investigated the relationship between breastfeeding, maternal obesity, and maternal glucose metabolism postpartum, with beta cell function as a primary outcome measure. This prospective study recruited 106 pregnant women (44% obese) who underwent a 75 g, 2-hour oral glucose tolerance test (OGTT) between the 3rd and 5th months postpartum. The relationship between breastfeeding status, maternal prolactin concentrations, maternal obesity, and fasting and dynamic indices of glucose metabolism was tested. It was noted that during the study visit at a mean of 122 days after delivery, 47% of the obese women and 68% of non-obese women were breastfeeding. The findings revealed that lactation and higher prolactin concentrations were associated with lower pre-pregnancy weight and lower postpartum insulin concentrations. In addition, prehepatic beta-cell function was decreased in both obese and non-obese lactating women. Prehepatic beta-cell function and Stumvoll 1st phase insulin secretion index, but not BMI, were independently and negatively associated with breastfeeding and circulating prolactin concentrations. Hence, it was concluded that beta-cell function during lactation relates to breastfeeding and circulating prolactin concentrations, independent of obesity. It was stated that the well-known positive effects of lactation on maternal and offspring outcomes might reflect a causative relationship of higher breastfeeding rates in metabolically healthier women.