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

The impact of the quality and quantity of carbohydrate intake on glycaemic control and pregnancy outcome was evaluated with focus on pregnant women with type 1 diabetes. For women with type 1 diabetes, a gestational weight gain within the lower range of the guidelines of the Institute of Medicine (IOM) is generally recommended. A low-glycaemic index diet is considered safe, and has shown, positive effects on the glycaemic control and pregnancy outcomes for both healthy women, those with type 2 diabetic and gestational diabetes (GDM). In general, carbohydrate counting does improve glycaemic control in type 1 diabetes. A moderately low carbohydrate diet with a carbohydrate content of 40% of the calories results in better glycaemic control and comparable obstetric outcomes in type 2 diabetes and GDM when compared to a diet with a higher carbohydrate content, and is regarded safe in diabetic pregnancy. In type 1 diabetes pregnancy, a moderately low carbohydrate diet with 40% carbohydrates has been suggested; however, a minimum intake of 175 g carbohydrate daily is recommended. Despite limited evidence the combination of a low-glycaemic index diet with a moderately low carbohydrate intake, using carbohydrate counting can be recommended for pregnant women with type 1 diabetes.

In pregnant women with type 1 diabetes, a low but sufficient, intake of carbohydrates is important to aim for near normal glycemic control. However, knowledge about the carbohydrate intake in this group is limited. To assess the average quantity and quality of carbohydrate intake in pregnant women with type 1diabetes compared to healthy pregnant women and current dietary reference intakes. A narrative literature search was performed in PubMed, Embase, and Cochrane Library and by using a snow‐ball search technique to identify papers published on studies conducted in industrialized countries within the last 20 years. Intakes of carbohydrate were assessed qualitatively in relation to the Dietary Reference Intakes recommended by the American Diabetes Association and quantitatively as mean intake of dietary fiber. Five observational studies including 810 pregnant women with type 1 diabetes and 15 observational studies with a total of 118,246 healthy pregnant women were identified. The mean total carbohydrate intake was within the Acceptable Macronutrient Distribution Range (45%–64% of energy intake) in both groups. In pregnant women with type 1 diabetes, the average total intake was 218 ± 19 g/day, which was 20% (53 g/day) lower than in healthy pregnant women. Mean intake of dietary fiber in women with diabetes was lower than the recommended adequate intake for healthy women. With the limitations of pronounced heterogeneity across the included studies, pregnant women with type 1 diabetes reported a mean total carbohydrate intake, which was lower than in healthy pregnant women but still within the recommended range.

Background: We aimed to explore insulin pump settings in breastfeeding women with type 1 diabetes. Methods: Thirteen unselected breastfeeding women with type 1 diabetes on insulin pump therapy were included consecutively from April 2016 to October 2017. Blinded continuous glucose monitoring (CGM) for 6 days was applied at 1, 2, and 6 months after delivery. Recommendations were intake of 210 g carbohydrate daily while aiming for glucose target range 4.0-10.0 mmol/L and avoiding hypoglycemia. Immediately after delivery a reduction of total insulin dose by 30% of the prepregnancy dose was recommended. Insulin pump target glucose was 5.8 mmol/L. Results: Median diabetes duration was 22 (range 13-36) years. At 1, 2, and 6 months, 13, 11, and 8 women, respectively, were breastfeeding and spent ‡70.8% (25%-99%) of time in the glucose target range and £3.8% (0%-15.5%) of time with CGM <4.0 mmol/L at night-time and for 24 h. None of the women experienced severe hypoglycemia. HbA1c was 58 (47-72) mmol/mol and 52 (44-60) at 6 months and prepregnancy, respectively, P = 0.18. At 1, 2, and 6 months, the insulin pump settings remained almost stable with basal insulin rates (at 03.00, 08.00, 12.00, and 18.00) 14% lower and the carbohydrate-to-insulin ratios 10% higher than the prepregnancy settings. Conclusions: In breastfeeding women with type 1 diabetes who consumed sufficient amounts of carbohydrates and obtained appropriate glycemic control, the basal insulin rates were 14% lower and carbohydrate-to-insulin ratios 10% higher than before pregnancy. These data are useful when recommending insulin pump settings after delivery.

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 &lt;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 &lt;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. Disclosure 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.