Impact of heatwaves on glycemic control in adults with type 1 diabetes using hybrid closed-loop systems

To evaluate the effect of the August´s 2023 heatwaves over glycemic control in adults with type 1 diabetes (T1D) treated with advance hybrid closed-loop systems (AHCL). Cross-sectional retrospective analysis of adult patients with T1D in Castilla-La Mancha (south-central Spanish region) using AHCL during the August´s 2023 heatwaves period. Primary outcome was change in time in range (TIR) 3.0-10 mmol/L (70-180 mg/dL) of interstitial glucose after the end of the heatwaves period. A total of 193 T1D patients were analyzed. TIR remained constant after the end of the heatwaves period (0.5% [95% CI -0.3, 1.3; P = 0.236]). No differences were observed among the rest of glycometric index. The percentage of patients meeting all the recommendations of the International Consensus of Time in Range was similar during the heatwaves period than after it ended (44.6% vs. 45.6%, P = 1.000). Finally, the percentage of time in automatization and daily insulin dose also stayed stable (0.5% [95% CI -1.4, 2.4; P = 0.601] and 0.0 UI/day [95% CI -1.0, 1.0; P = 0.981], respectively). Adults with T1D treated with AHCL maintained glycemic control during August´s 2023 heatwaves. These data raise the possibility that AHCL systems could help protect T1D patients from the effects of heatwaves on glycemic control.