Closed-Loop Insulin Delivery Versus Sensor-Augmented Pump Therapy in Older Adults With Type 1 Diabetes (ORACL): A Randomized, Crossover Trial

Objective

To assess the efficacy and safety of closed-loop insulin delivery compared with sensor-augmented pump therapy among older adults with type 1 diabetes.

Research Design and Methods

This open-label randomized (1:1), crossover trial compared 4 months of closed-loop versus sensor-augmented pump therapy. Eligible adults were aged ≥60 years, with type 1 diabetes (duration ≥10 years), using an insulin pump. The primary outcome was continuous glucose monitoring (CGM) time in range (TIR; 3.9–10.0 mmol/L).

Results

Thirty participants (mean age 67 years [SD 5]; median type 1 diabetes duration 38 years [IQR 20–47]) were randomized, n=15 to each sequence; all completed the trial. The mean TIR was 75.2% (6.3) during the closed-loop stage and 69.0% (9.1) during the sensor-augmented pump stage (difference 6.2 percentage points [95% CI 4.4, 8.0]; P <0.0001). All prespecified CGM metrics favored closed loop over sensor-augmented pump; benefits were greatest overnight. Closed loop reduced CGM time <3.9 mmol/L during 24 h/day by 0.5 percentage points (0.3, 1.1; P = 0.0005) and overnight by 0.8 percentage points (0.4, 1.1; P <0.0001) compared with sensor-augmented pump. There was no significant difference in HbA_1c between closed-loop versus sensor-augmented pump stages (7.3% [7.1–7.5] | 56 mmol/mol [54–59] versus 7.5% [7.1–7.9] | 59 mmol/mol [54–62], respectively; P = 0.13). Three severe hypoglycemia events occurred during the closed-loop stage and two occurred during the sensor-augmented pump stage; no hypoglycemic events required hospitalization. One episode of diabetic ketoacidosis occurred during the sensor-augmented pump stage; no serious adverse events occurred during the closed-loop stage.

Conclusion

Closed-loop therapy is an effective treatment option for older adults with long duration type 1 diabetes and no safety issues were identified. These older adults had higher TIR accompanied by less time below range during closed-loop than sensor-augmented pump therapy. Of particular clinical importance, closed loop reduced the time spent in hypoglycemic range overnight.