Background: Hybrid closed loop (HCL) technology is now standard of care for women with type 1 diabetes in pregnancy in the United Kingdom, but there is minimal evidence to guide HCL use in the preconception period, peripartum, and postnatally. We used real-world data to assess whether HCL use offered benefits upon glycemia in the preconception, peripartum, and postnatal periods.
Methods: This single-center retrospective observational study assesses the effect of HCL use upon HbA1c and continuous glucose monitoring (CGM) metrics, including time-in-range (TIR; 3.9-10.0 mmol/L; 72-180 mg/dL) or pregnancy time-in-range (TIRp; 3.5-7.8 mmol/L; 63-140 mg/dL) before (n = 46), during (n = 21), and after (n = 25) pregnancy. Data (mean (SD)) were analyzed using paired t tests (limit P < .05).
Results: Preconception initiation of HCL was associated with a reduction of HbA1c from 62.4 (14.0) to 54.2 (7.7) mmol/mol at three to six months (7.9 (1.3) to 7.1 (0.7) %; P < .0001). The TIR increased from 49% at baseline to 65% at one week (P < .001) and 72% at six months (P < .001) after initiation. Time-below-range (TBR) fell from 3.2% at baseline to 2.1% at one week (P = .006) and 2.1% at three months (P = .042). Pregnancy initiation of HCL was associated with a reduction of HbA1c from 61.2 (14.6) to 48.1 (8.6) mmol/mol at three months (n = 36; P < .0001) and increased TIRp (37% baseline to 57% after one week; P < .0001). Patients using HCL postnatally at one month had TIR 70% and TBR 1.8%.
Conclusions: When started preconception or in pregnancy, HCL significantly reduces HbA1c at three months and improves TIR by 15% to 20% within one week.
Keywords: hybrid closed loop; post natal; preconception; pregnancy; type 1 diabetes.