218-OR: Revisiting the Rule of 500: Data-Driven Insights from Sensor Augmented Pump Therapy

Abstract

The rule of 500 is widely used to calculate the insulin to carbohydrate ratio (ICR) for T1D patients, where ICR is calculated as 500/ total daily dose (TDD) with TDD being the average daily sum of basal+bolus insulin. We analyzed data from the Tidepool Big Data Donation Project for 100 participants on sensor-augmented pump (SAP) therapy, to compute a new ICR prediction factor (ICR-PF) defined as the TDD multiplied by the ICR. Glucose level, bolus delivery, basal delivery, ICR, and correction factor were continuously recorded. For each month of data, we calculated the average daily TDD. For reliable results, we selected a subset of patients for further analyses who showed successful post-meal glycemic control, defined as both average rise in glucose and variability of glucose rise (standard deviation) below 30 mg/dL; 66 out of 72 adults (91.7%) and 18 out of 28 pediatrics (64.3%) demonstrated successful control as per these criteria. Baseline demographics for this subset are provided in Table 1. Adults had a slightly lower ICR-PF of 356.0 [261.8,437.7] (median[IQR]), compared to pediatric participants (405.5 [286.4,488.5], p = 0.35 ). The computed ICR-PF varied across the months of pump use for both adult (coefficient of variation 10.6% [6.6,14.6]%) and pediatric participants (10.9% [9.4,19.9]%, p = 0.17). Our results show the promise of a novel data-driven, personalized ICR-PF for optimizing glycemic control in T1D. Disclosure S. Barua: None. A. Zhang: None. A. Sabharwal: None. D. Desalvo: Consultant; Self; Insulet Corporation, Research Support; Self; Insulet Corporation, Speaker’s Bureau; Self; Dexcom, Inc.