Glycemic Outcomes in Baseline Hemoglobin A1C Subgroups in the International Diabetes Closed-Loop Trial

Abstract

Using a closed-loop system significantly improves time in range (TIR) 70-180 mg/dL in patients with type 1 diabetes (T1D). In a 6-month RCT, 112 subjects were randomly assigned to closed-loop control (Tandem Control-IQ) after obtaining 2 weeks of baseline Continuous glucose monitoring (CGM) data from sensor-augmented pump therapy. We compared glycemic outcomes from baseline to end of study among subgroups classified by baseline HbA1c levels. All HbA1c subgroups showed an improvement in TIR due to reduction of both hyperglycemia and hypoglycemia. Those with HbA1c <6.5% improved mostly by reducing nocturnal hypoglycemia due to the automated basal insulin adjustments. Those with HbA1c ≥8.5% improved mostly by reducing daytime and nocturnal hyperglycemia due to both automated basal insulin adjustments and correction boluses during the day. There does not appear to be any reason to exclude individuals with T1D from automated insulin delivery based on their HbA1c. Clinical Trial Identifier: NCT03563313.

Keywords: Closed-loop system; Continuous glucose monitoring; Glycemic management; International Diabetes Closed-Loop Trial; Time in range; Type 1 diabetes.

FIG. 1.

Change in daytime (A) versus nighttime (B) glycemic control and median number of boluses per 24 h (C), by baseline HbA1c subgroups. (A) Solid black shows <70 mg/dL, solid white shows 70–180 mg/dL, and striped bar shows >180 mg/dL. (B) Solid black shows <70 mg/dL, solid white shows 70–180 mg/dL, and striped bar shows >180 mg/dL. (C) Solid blue bar shows manual boluses with Announced CHO (meal boluses), solid white bar shows manual boluses with No CHO (correction boluses), and solid red bar shows Automated Correction Boluses.