Low prevalence of hypoglycaemia documented by continuous glucose monitoring during breastfeeding in women with type 1 diabetes who use carbohydrate counting – a preliminary report

Aim: To evaluate the glucose levels over 24 hours and at night-time during breastfeeding, and to compare weight and insulin requirements before and after pregnancy in women with type 1 diabetes. Methods: Prospective study of 13 consecutive breastfeeding women (mean 31.8 (SD ±4.0) years, 46% nulliparous) with type 1 diabetes for 22 (±8.6) years. All were experienced in carbohydrate counting. Eight women (62%) were on insulin pump. At 34 (±9.5) and 68 (±18.7) days after singleton delivery, blinded continuous glucose monitoring (CGM) was applied for six days. Thereafter insulin dose was adjusted. Results: At 34 and 68 days after delivery glucose levels were similar over 24 hours (8.2 (±1.4) and 8.2 (±1.8) mmol/l, p=0.94) and at night-time (8.2 (±1.6) and 8.0 (±2.3) mmol/l, p=0.79). The percentage of time spent with CGM <4.0 mmol/l was similar over 24 hours (median 5.8 (range 0-12.2) and 3.4 (0-19.7), p=0.58) and at night-time (3.3 (0-12.0) and 5.4 (0-36.1), p=0.15). The number of episodes with mild hypoglycaemia in the previous week was lower at 68 than at 34 days (3 (0-10) vs. 4 (1-16)), but this did not reach statistical significance, p=0.15. Insulin dose tended to be 20% lower at 34 days than before pregnancy (0.41 (±0.14) vs. 0.53 (±0.18) IE/kg/24-h, p=0.08). Maternal weight at 34 days was close to pre-pregnancy weight (72.6 (±10.1) vs. 71.1 (±10.9) kg, p=0.54). Conclusion: Breastfeeding women with type 1 diabetes, who use carbohydrate counting, return to pre-pregnancy weight within a month after delivery and have a low prevalence of hypoglycaemia documented by CGM.