Aim: Hypoglycemia in association with breastfeeding is a feared condition in women with type 1 diabetes. Thus, routine carbohydrate intake at each night-time breastfeeding is often recommended despite lack of evidence. We evaluated glucose levels during breastfeeding with focus on whether night-time breastfeeding induced hypoglycemia in women with type 1 diabetes.

Methods: Prospective study of 25 consecutive breastfeeding women (mean age 30.8 (SD ±5.9) years, 64% nulliparous, singleton pregnancy) with type 1 diabetes for 18.8 (±10.5) years. All were experienced in carbohydrate counting with 44% on insulin pump and 56% on multiple daily injections. At 33 (±7.2) and 66 (±14.2) days postpartum blinded continuous glucose monitoring (CGM) was applied for six days and the women recorded breastfeedings and carbohydrate intake.

Results: At both CGM periods mean glucose levels were similar at night (11 pm to 7 am) (8.3 (±1.7) and 8.7 (±2.5) mmol/l, p=0.56) and over 24 hours (8.4 (±1.5) and 8.7 (±2.1) mmol/l, p=0.56). The percentage of time <4.0 mmol/l was similar at night (median 5.8% (range 0-20.8) and 3.1% (0-36.1), p=0.24) and over 24 hours (5.0% (0-19.8) and 3.9% (0-22.8), p=0.75). At 33 days postpartum maternal weight was close to the pre-pregnancy weight (79.1 (±15.0) vs. 75.6 (±14.2) kg, p=0.50) while insulin dose was 18% lower than before pregnancy (p=0.04). A total of 340 night-time breastfeedings were recorded with 2 (0-4) breastfeedings per night. Carbohydrate was ingested at 42 (12%) of the breastfeedings. CGM <4.0 mmol/l within three hours after night-time breastfeeding occurred after 5% of breastfeedings.

Conclusion: Despite almost 300 night-time breastfeedings without carbohydrate intake, hypoglycemia within 3 hours after breastfeeding was rare. The recommendation of routine carbohydrate intake at night-time breastfeeding in women with type 1 diabetes on modern insulin treatment who count carbohydrate may be obsolete.


L. Ringholm: None. A.B. Roskjær: None. S. Engberg: None. H.U. Andersen: Advisory Panel; Self; Novo Nordisk A/S. Stock/Shareholder; Self; Novo Nordisk A/S. Advisory Panel; Self; AstraZeneca. E. Hommel: None. A.L. Secher: None. P. Damm: Advisory Panel; Self; Novo Nordisk A/S. Other Relationship; Self; Novo Nordisk A/S. E.R. Mathiesen: Speaker's Bureau; Self; Novo Nordisk A/S. Other Relationship; Self; Novo Nordisk A/S, Novo Nordisk Foundation, Novo Nordisk A/S.

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