Glycaemic patterns during breastfeeding with postpartum use of closed-loop insulin delivery in women with type 1 diabetes

Abstract

Aims/hypothesis: This study aimed to describe the relationship between breastfeeding episodes and maternal glucose levels, and to assess whether this differs with closed-loop vs open-loop (sensor-augmented pump) insulin therapy.

Methods: Infant-feeding diaries were collected at 6 weeks, 12 weeks and 24 weeks postpartum in a trial of postpartum closed-loop use in 18 women with type 1 diabetes. Continuous glucose monitoring (CGM) data were used to identify maternal glucose patterns within the 3 h of breastfeeding episodes. Generalised mixed models adjusted for breastfeeding episodes in the same woman, repeat breastfeeding episodes, carbohydrate intake, infant age at time of feeding and early pregnancy HbA_1c. This was a secondary analysis of data collected during a randomised trial (ClinicalTrials.gov registration no. NCT04420728).

Results: CGM glucose remained above 3.9 mmol/l in the 3 h post-breastfeeding for 93% (397/427) of breastfeeding episodes. There was an overall decrease in glucose at nighttime within 3 h of breastfeeding (1.1 mmol l^-1 h^-1 decrease on average; p=0.009). A decrease in nighttime glucose was observed with open-loop therapy (1.2 ± 0.5 mmol/l) but was blunted with closed-loop therapy (0.4 ± 0.3 mmol/l; p<0.01, open-loop vs closed-loop).

Conclusions/interpretation: There is a small decrease in glucose after nighttime breastfeeding that usually does not result in maternal hypoglycaemia; this appears to be blunted with the use of closed-loop therapy.

Keywords: Breastfeeding; Closed-loop insulin delivery; Continuous glucose monitoring; Hypoglycaemia; Insulin pump therapy; Type 1 diabetes.

Fig. 1

Glycaemic response to (a) nighttime breastfeeding (open-loop therapy, n=57 breastfeeding episodes; closed-loop therapy, n=70 breastfeeding episodes) and (b) daytime breastfeeding (open-loop therapy, n=103 breastfeeding episodes; closed-loop therapy, n=197 breastfeeding episodes). Data are presented as medians (central solid lines) and interquartile ranges (shaded areas); blue, open-loop therapy; orange, closed-loop therapy. In (a), p<0.01 for decreased in blood glucose within 3 h of the initiation of breastfeeding with use of closed-loop vs open-loop therapy