Insulin In Human Milk:Effect Of Correlation Factors

ObjectiveTo determine the human milk insulin concentrations of healthy lactating mothers and gestational diabetes mellitus(GDM) or gestational impaired glucose tolerance(GIGT) lactating mothers in Beijing, and to evaluate the variations between human milk insulin concentrations in colostrum and mature milk, which were collected from healthy lactating mothers. To study and research if human milk insulin concentrations are affected by such correlative factors as maternal age, gestational age, mode of delivery, body mass index(BMI) and feeding patterns. To explore if human milk insulin has some effect on growth and developments of neonates.MethodsAn observational study was carried out in the department of obstetrics and pediatrics in PUMCH, including148healthy lactating mothers,30GDM and16GIGT lactating mothers with their neonates. Colostrum and mature milk samples were collected, together with relative data such as maternal age, gestational age, mode of delivery, BMI, feeding patterns and the blood glucose level in the duration of pregnancy of GDM and GIGT lactating mothers. The indexes of body length, weight and head circumference of these neonates were recorded and followed up for6weeks and3months after birth. The human milk insulin concentrations were determined by radioimmnuoassay.Results(1). The colostrum insulin concentrations were29.24(17.60,47.27) μU/ml, and the insulin concentrations of mature milk at the sixth week and on the third month were37.68(26.39,56.11)μU/ml and37.14(29.88,52.01)μU/ml respectively.(2). The insulin concentrations of colostrum were not significantly different from that of the mature milk at the sixth week, in the group of healthy lactating mothers. However, in the GDM/GIGT group, the colostrum insulin concentrations [28.81(13.84,43.14) μU/ml]were significantly lower than that of the mature milk at the sixth week]57.50(36.70,82.73) μU/ml](P=0.000).(3). No significant differences were observed in the colustrum insulin concentrations between the group of healthy lactating mothers and the GDM/GIGT group, yet of the insulin concentrations in the mature milk at the sixth week, the healthy group [35.88(25.91,46.85)μU/ml] was lower than that of the GDM/GIGT group[57.50(36.70,82.73) μU/ml](P=0.015).(4). The colustrum insulin concentrations of uterine-incision delivery mothers[23.64(14.90,38.51)μU/ml] were apparently lower than that of vaginal delivery ones [38.89(23.14,65.54)μU/ml](P=0.000), but no differences occurred in the mature milk at the sixth week.(5). The insulin concentrations of mature milk at the sixth week in mixed feeding cases [42.58(26.60,73.06)μU/ml] were significantly higher than that of breast feeding cases[36.32(26.00,46.16)μU/ml]. In addition, the human milk insulin concentrations of mixed feeding cases were significantly increased in postpartum duration.(6). Both concentrations of insulin in the colostrum and mature milk at the sixth week were positively correlated with maternal BMI (P<0.01), respectively.(7). The insulin concentrations of colostrum and mature milk were not significantly influenced by maternal age, gestational age, neonates gender.(8). In breast feeding cases, body length, weight and head circumference of neonates were not influenced by the insulin concentrations of colostrum and mature milk.ConclusionsThe human milk insulin concentrations in GDM/GIGT group were significantly increased in the duration of lactation, with no variations in the healthy mothers group. The mode of delivery had significant effect on the colostrum insulin concentrations, in addition, the insulin concentrations of the mature milk at the sixth week were significantly influenced by GDM/GIGT and the feeding patterns in postpartum duration. The human milk insulin concentrations were positively correlated with maternal BMI. No evidences showed the effects of human milk insulin on the development and growth of neonates.