Breastfeeding at night is rarely followed by hypoglycaemia in women with type 1 diabetes using carbohydrate counting and flexible insulin therapy

Abstract

Aims/hypothesis Hypoglycaemia in association with breastfeeding is a feared condition in mothers with type 1 diabetes. Thus, routine carbohydrate intake at each breastfeed, particularly at night, is often recommended despite lack of evidence. We aimed to evaluate glucose levels during breastfeeding, focusing on whether night-time breastfeeding induced hypoglycaemia in mothers with type 1 diabetes. Methods Of 43 consecutive mothers with type 1 diabetes, 33 (77%) were included prospectively 1 month after a singleton delivery. Twenty-six mothers (mean [SD] age 30.7 [5.8] years, mean [SD] duration of diabetes 18.6 [10.3] years) were breastfeeding and seven mothers (mean [SD] age 31.7 [5.6] years, mean [SD] duration of diabetes 20.4 [6.2] years) were bottle-feeding their infants with formula. All were experienced in carbohydrate counting using individually tailored insulin therapy with insulin analogues (45% on insulin pump, 55% on multiple daily injections). Thirty-two women with type 1 diabetes, matched for age ±1 year and BMI ±1 kg/m 2 , who had not given birth or breastfed in the previous year, served as a control group. Blinded continuous glucose monitoring (CGM) for 6 days was applied at 1, 2 and 6 months postpartum in the breastfeeding mothers who recorded breastfeeds and carbohydrate intake at each CGM period. CGM was applied at 1 month postpartum in the formula-feeding mothers and once in the control women. The insulin dose was individually tailored after each CGM period. Results The percentage of night-time spent with CGM <4.0 mmol/l was low (4.6%, 3.1% and 2.7% at each CGM period in the breastfeeding mothers vs 1.6% in the control women, p = 0.77), and the breastfeeding mothers spent a greater proportion of the night-time in the target range of 4.0-10.0 mmol/l (p = 0.01). Symptomatic hypoglycaemia occurred two or three times per week at 1, 2 and 6 months postpartum in both breastfeeding mothers and the control women. Severe hypoglycaemia was reported by one mother (3%) during the 6 month postpartum period and by one control woman (3%) in the previous year (p = 0.74). In breastfeeding mothers at 1 month, the insulin dose was 18% (−67% to +48%) lower than before pregnancy (p = 0.04). In total, carbohydrate was not consumed in relation to 438 recorded night-time breastfeeds, and CGM <4.0 mmol/l within 3 h occurred after 20 (4.6%) of these breastfeeds. Conclusions/interpretation The percentage of night-time spent in hypoglycaemia was low in the breastfeeding mothers with type 1 diabetes and was similar in the control women. Breastfeeding at night-time rarely induced hypoglycaemia. The historical recommendation of routine carbohydrate intake at night-time breastfeeding may be obsolete in mothers with type 1 diabetes who have properly reduced insulin dose with sufficient carbohydrate intake. Trial registration ClinicalTrials.gov NCT02898428

Insulin Pump Settings During Breastfeeding in Women with Type 1 Diabetes

“…Target SMPG was 4.0-10.0 mmol/L. 8 Seven of the 13 women used CGM continuously, whereof 1 woman accepted to use additional Ipro CGM for this study. All routine CGM devices used Enlite2 sensors and the open CGM data of the remaining six women were used for analysis.…”

“…This was an explorative study of 13 consecutive breastfeeding women with type 1 diabetes on insulin pump therapy who also participated in a previously published cohort study, 8 which included 33 women with type 1 diabetes where hypoglycemia was investigated with intermittent CGM after delivery. This study was a secondary analysis and included all women on insulin pump therapy who were breastfeeding for at least 1 month after delivery and whose insulin pump uploads were available during breastfeeding.…”

“…The women were encouraged to continue normal daily living during each 6-day CGM recording period without changing breastfeeding, food, or exercise patterns. 8 Capillary blood glucose was measured for calibration with a Contour Ò Next glucometer (Ascensia Diabetes Care Denmark Aps) 1 and 3 h after insertion. The women were recommended to perform at least four self-monitoring of plasma glucose (SMPG) measurements daily, before main meals and before bedtime.…”

“…The prevalence of hypoglycemia was low in both groups and breastfeeding at night-time rarely induced hypoglycemia. 8 The insulin doses were individually reduced immediately after delivery and the women consumed sufficient amounts of carbohydrate during daytime. 8 In 2019, an international consensus group recommended that nonpregnant adults with diabetes using CGM spend >70% of time in the range 3.9-10.0 mmol/L and <4% of time <3.9 mmol/L.…”

“…8 The insulin doses were individually reduced immediately after delivery and the women consumed sufficient amounts of carbohydrate during daytime. 8 In 2019, an international consensus group recommended that nonpregnant adults with diabetes using CGM spend >70% of time in the range 3.9-10.0 mmol/L and <4% of time <3.9 mmol/L. 9 The insulin pump settings include the following five components: (1) basal insulin rates, (2) carbohydrate-toinsulin ratio, (3) insulin sensitivity factor, (4) target plasma glucose, and (5) insulin action time.…”