Breastfeeding effect on glucose tolerance assessment in women with previous gestational diabetes mellitus: A randomized controlled trial

Abstract Aims To test whether breastfeeding during the oral glucose tolerance test (OGTT) affects glucose and insulin outcomes (main outcome: 120 min plasma glucose). Methods A randomized crossover trial was conducted in 20 women with prior gestational diabetes mellitus. Each woman undertook two OGTTs in the first 3 months after delivery, breastfeeding the infant in one and avoiding breastfeeding in the other. Glucose and insulin were measured at 0, 30, 60 and 120 min. Statistics included: T‐test for paired data, general linear model (GLM) for repeated measures. Analysis of covariance (ANCOVA) was used to adjust for glucose and insulin values at 0 min. Statistical dispersion for GLM and ANCOVA outcomes is expressed as standard error. Results In the OGTTs with breastfeeding, higher values were observed for overall glucose and insulin concentrations, glucose and insulin peaks and individual time points of glucose (at 0, 30 and 60 min) and insulin (at 0 and 60 min) but without differences at 120 min (glucose 6.7 ± 0.3 vs. 6.9 ± 0.3 mmol/L, p = 0.506). The rate of abnormal tests was not different. ANCOVA confirmed higher postchallenge glucose values in the OGTT with breastfeeding and similar glucose values at 120 min. Conclusions According to the results of this randomized trial, we conclude that breastfeeding during the OGTT resulted in similar 120 min glucose concentration and glycaemic status categorization. However, breastfeeding during the OGTT led to clear differences in glucose and insulin values in the first hour, that warrant further studies.