Safety and Efficacy of an Adaptive Bolus Calculator for Type 1 Diabetes: A Randomized Controlled Crossover Study

Background: The Advanced Bolus Calculator for Type 1 Diabetes (ABC4D) is a decision support system using the artificial intelligence technique of case-based reasoning to adapt and personalize insulin bolus doses. The integrated system comprises a smartphone application and clinical web portal. We aimed to assess the safety and efficacy of the ABC4D (intervention) compared with a nonadaptive bolus calculator (control). Methods: This was a prospective randomized controlled crossover study. Following a 2-week run-in period, participants were randomized to ABC4D or control for 12 weeks. After a 6-week washout period, participants crossed over for 12 weeks. The primary outcome was difference in % time in range (%TIR) (3.9-10.0 mmol/L [70-180 mg/dL]) change during the daytime (07:00-22:00) between groups. Results: Thirty-seven adults with type 1 diabetes on multiple daily injections of insulin were randomized, median (interquartile range [IQR]) age 44.7 (28.2-55.2) years, diabetes duration 15.0 (9.5-29.0) years, and glycated hemoglobin 61.0 (58.0-67.0) mmol/mol (7.7 [7.5-8.3]%). Data from 33 participants were analyzed. There was no significant difference in daytime %TIR change with ABC4D compared with control (median [IQR] +0.1 [-2.6 to +4.0]% vs. +1.9 [-3.8 to +10.1]%; P = 0.53). Participants accepted fewer meal dose recommendations in the intervention compared with control (78.7 [55.8-97.6]% vs. 93.5 [73.8-100]%; P = 0.009), with a greater reduction in insulin dosage from that recommended. Conclusion: The ABC4D is safe for adapting insulin bolus doses and provided the same level of glycemic control as the nonadaptive bolus calculator. Results suggest that participants did not follow the ABC4D recommendations as frequently as control, impacting its effectiveness. Clinical Trials Registration: clinicaltrials.gov NCT03963219 (Phase 5).