Effect of daily insulin delivery variability on glycemic outcomes in patients with type 1 diabetes mellitus using an automated insulin delivery system

Automated insulin delivery (AID) systems are central to managing type 1 diabetes mellitus (T1DM), using continuous glucose monitoring (CGM) to adjust basal insulin (BI). Certain systems, such as the MiniMed™ 780G, also provide automated correction boluses (AB), while manual boluses (MB) are administered in response to carbohydrate intake. Despite the adaptive nature of these technologies, the influence of variability in individual insulin delivery components on glycemic outcomes remains insufficiently characterized. This retrospective study analyzed 7,710 patient-days from 257 T1DM patients (236 adults, 21 pediatric) using the MiniMed™ 780G system for over six months. Variability in BI, AB, and MB-measured as BI-V%, AB-V%, and MB-V%-was assessed over 30-day periods and correlated with glycemic metrics including time in range (TIR70-180), time above/below range (TAR, TBR), glucose coefficient of variation (CV), and glucose management index (GMI). Multivariate and ROC analyses were conducted. Mean TIR70-180 exceeded 70 % in both groups. AB-V% (36.9 %) was significantly higher than BI-V% (16.8 %) and MB-V% (19.1 %). MB-V% was negatively associated with TIR and positively with TAR, while AB-V% showed the opposite. AB-V% >32.3 % and MB-V% ≤18.2 % predicted achieving TIR > 70 %. Variability in insulin delivery, especially AB and MB, affects glycemic control in T1DM. Monitoring and optimizing these components may improve AID system effectiveness.