Higher rates of large‐for‐gestational‐age newborns mediated by excess maternal weight gain in pregnancies with Type 1 diabetes and use of continuous subcutaneous insulin infusion vs multiple dose insulin injection

Abstract

Aims To compare glycaemic control, maternal and neonatal outcomes in pregnancies with Type 1 diabetes, managed either by continuous subcutaneous insulin infusion, multiple daily insulin injection or switch from multiple daily insulin injection (MDI) to continuous subcutaneous insulin infusion (CSII) in early pregnancy. Research design and methods Data from 339 singleton pregnancies were retrospectively reviewed. HbA1c values were measured preconception and in each trimester. In a secondary analysis, use of CSII pre‐pregnancy was compared with initiation of CSII during pregnancy. Results MDI was used in 140 pregnancies (41.3%) and CSII was used in 199 (58.7%), including 34 pregnancies (10.0%) during which the women switched to CSII. In pregnancies during which CSII was used duration of diabetes [median (interquartile range) 16.0 (8.0–23.0) years vs 11.0 (5.5–17.5) years; P<0.001] was longer, and the Institute of Medicine recommendations for appropriate weight gain were exceeded more often (64.8% vs. 50.8%; P=0.01). CSII use and pre‐pregnancy BMI were independent predictors of excess weight gain. There was no difference in glucose control, but CSII was associated with higher birth weight [median (interquartile range) 3720 (3365–4100) g vs 3360 (3365–4100) g; P<0.001] and higher large‐for‐gestational‐age (LGA) rate (44.7% vs. 33.6%; P=0.04) than MDI. HbA1c concentration in the third trimester and excess weight gain were predictive of LGA infants [odds ratio 2.33 (95% CI 1.54–3.51); P<0.001 and 1.89 (95% CI 1.02–3.51); P=0.04]. In pregnancies where CSII therapy was initiated in the first trimester and in those with pre‐pregnancy use, similar glucose control and outcome was achieved. Conclusions There was no advantage of CSII with respect to glycaemic control and neonatal outcomes. The rate of LGA neonates was higher in the CSII group, possibly mediated by excess maternal weight gain, which was more frequent than in women treated with MDI.

Why might pumps fail in pregnant women with Type 1 diabetes?

“…The authors of both these studies stated that CSII and MDI were not randomly allocated in their studies, which may have led to selection bias. For the study by Hauffe et al ., CSII‐treated women had an average duration of diabetes that was 5 years longer, with almost twice the rate of microvascular complications (non‐significant), which suggests more unstable and difficult‐to‐treat diabetes ; however, these differences were not present in the CONCEPPT trial, in which pump‐treated women were more likely to be married, to have received preconception vitamin replacement therapies and to have a higher education level , as is usually reported when CSII users are compared with MDI users. For both studies, the proportion of women who smoked during pregnancy was twice as high among women on MDI .…”

“…For the study by Hauffe et al ., CSII‐treated women had an average duration of diabetes that was 5 years longer, with almost twice the rate of microvascular complications (non‐significant), which suggests more unstable and difficult‐to‐treat diabetes ; however, these differences were not present in the CONCEPPT trial, in which pump‐treated women were more likely to be married, to have received preconception vitamin replacement therapies and to have a higher education level , as is usually reported when CSII users are compared with MDI users. For both studies, the proportion of women who smoked during pregnancy was twice as high among women on MDI . Smoking is associated with less gestational weight gain and fewer large‐for‐gestational‐age babies , and it may protect against maternal hypertensive disorders, as mentioned in the article by Feig et al .…”

“…We read with interest the article by Hauffe et al . , who reported higher rates of large‐for‐ gestational‐age newborns and greater maternal gestational weight gain in women with Type 1 diabetes who were treated with continuous subcutaneous insulin infusion (CSII), compared with those treated with multiple daily insulin injections (MDI) during pregnancy. A few months previously, Feig et al .…”

“…These reports call into question the use of CSII in most pregnant women with Type 1 diabetes: 58.7% in the study by Hauffe et al . .…”

“…and Feig et al . hypothesized that postprandial hyperglycaemia may not be well controlled on CSII . After bolus infusion, which takes some minutes, the metabolic actions from infused vs injected insulin are not considered to be fundamentally different .…”