Metrics in pregnancy: is it the time for new glycaemic goals for pregnant women with type 1 diabetes? An experience with advanced hybrid closed loop.

Introduction: Recommended pregnancy specific Time in Range (TIR) 63-140 mg/dl is a quite wide range and, even if the goal of > 70% is achieved, the specific targets for fasting and mean glycaemia, which are much lower than 140 mg/dl, could not be complied. This case series aimed to explore the performance of an Advanced Hybrid closed Loop (AHCL) in pregnancy on a stricter glycaemic range.

Methods: We collected retrospective data about recommended glucose metrics and an hypothetic TITR 63-95 mg/dl, more suitable for fasting periods, from 11 type 1 diabetes patients, using Medtronic MiniMed™ 780G, with glucose target 100 mg/dl and Active Insulin Time 2 h, from preconceptional phase until delivery.

Results: TIR 63-140 mg/dl quickly improved throughout pregnancy, with progressively improving HbA1c and no significant changes in Time Below Range (TBR). TITR 63-95 mg/dl was 26% in the 1st trimester, 20% in the 2nd and 30% in the 3rd, corresponding to 6, 5 and 7 h per day, less than the hypothetic 8/24 hours of fasting. TAR > 140 reduced more compared to TAR > 95, reflecting a greater improve in postprandial values than in fasting.

Conclusions: Although the AHCL Medtronic MiniMed™ 780G helped improving glycaemic control during pregnancy, our patients spent very few hours in the range 63-95 mg/dl, probably because they did not reach fasting glucose goals. A stricter TIR may be hypothesized for pregnant women too, as an additional goal along with TIR 63-140 mg/dl, but studies are needed to explore the consequences on maternal and fetal outcomes.