Postprandial glucose control with hybrid closed-loop systems in adults with type 1 diabetes

Background: Hybrid Closed-Loop Systems (HCLS) may not perform optimally on postprandial glucose control. Moreover, the performance may vary between different systems. Aim: To evaluate how first-generation and advanced HCLSs manage meals varying in carbohydrates, fat, and protein. Materials and methods: According to a cross-sectional design, 7-day food records and HCLS reports from 120 adults with type 1 diabetes (MiniMed 670G, n=40; MiniMed 780G, n=49; Control-IQ, n=31) were analyzed. Breakfasts (n=570), lunches (n=658), and dinners (n=619) were divided according to the median of their Carbohydrate(g) / Fat(g) plus Protein(g) ratio (C/FP). After breakfast (4 hours), lunch (6 hours), and dinner (6 hours), CGM metrics and early and late glucose incremental-AUCs and delivered insulin doses were evaluated. The association of C/FP and type of HCLS with postprandial glucose and insulin patterns was analyzed by univariate ANOVA with a two-factor design. Results: Postprandial glucose time-in-range 70-180 mg/dl was optimal after breakfast (78.3±26.9%), lunch (72.7±26.1%), and dinner (70.8±27.3%), with no significant differences between users of different HCLS. Independent of C/FP, late glucose-iAUC after lunch was significantly lower in Control-IQ users than 670G and 780G users (p<0.05), with no significant differences at breakfast and dinner. Postprandial insulin pattern (Ins3-6h minus Ins0-3h) differed by type of HCLSs at lunch (p=0.026) and dinner (p<0.001), being the early (Ins0-3h) higher than the late insulin dose (Ins3-6h) in 670G and 780G users with an opposite pattern in Control-IQ users. Conclusion: The three HCLSs examined showed similar abilities to manage the glucose response to meals with different proportions of carbohydrates, fat, and protein. This was obtained through different automatic insulin delivery patterns.