Continuous glucose monitoring (CGM) has highlighted the gap that exists between our expectations of tight metabolic control and the realities of actually achieving this, particularly during type 1 diabetes pregnancy. Longitudinal measurements indicate that despite overall good HbA1c levels, pregnant women with type 1 diabetes spend 8 h/day with blood glucose levels above the recommended targets. New closed-loop (CL) or artificial pancreas approaches integrate insulin pump delivery (CSII) with CGM via computerized algorithms.
The vital component of a CL system for use during pregnancy is a control algorithm which can function safely despite the physiological changes in glucose turnover, endogenous glucose production, and insulin kinetics. We have defined these changes in type 1 diabetes pregnancy and completed proof-of-concept phase I feasibility studies evaluating overnight CL, in early (1216 weeks) and late (2832 weeks) gestation. Pilot feasibility studies demonstrated near-normal overnight glucose control (85100% time within the target range of 3.57.8 mmol/l), during early and late gestation. In a subsequent 24-h crossover study comparing CL vs conventional CSII, CL achieved excellent overnight control (95100% time in target), with 80% overall time in target, during meals, snacks and physical activity. Phase II unsupervised home studies evaluating the feasibility, safety and efficacy of CL in real-life home settings are currently underway with encouraging preliminary data.
The next challenge is to translate promising preliminary results into real-life benefits for mothers with type 1 diabetes and their offspring.