In July 2023, Italy experienced a sub-tropical anticyclone resulting in an exceptional heatwave across the country. Exposure to hot ambient conditions and heat stress have been linked to increased cardiovascular mortality and morbidity in individuals with diabetes, who also face distinct challenges in maintaining glycaemic control during extreme weather conditions. As global temperatures continue to rise, it becomes imperative to investigate how heatwaves influence diabetes management and to explore strategies to mitigate their effects. This study evaluated the impact of the 2023 heatwave in Rome on glycemic control in individuals with insulin-treated diabetes. Ambulatory glucose profile (AGP) data were available during the heatwave period (July 12 to July 25, 2023) and for a two-week period prior to the heatwave (June 17 to June 30, 2023), considered as a reference time. AGPs were obtained by either flash glucose monitoring (FGM) or continuous glucose monitoring (CGM) system. In our population (n=68, age: 50.3±17.8 years, BMI: 25.8±4.7 kg/m2, 46% females), sensor derived parameters of glycaemic control significantly changed between the pre- and heatwave period. We reported mean 4.6% TIR increase during the heatwave compared to the reference period (p=0.019), paralleled by reduced TAR (p=0.019) and TBR (p=0.026). At the multivariate analysis, sensor scan adherence was predictive of TIR change during the heatwave independent of age, sex, BMI, type of diabetes and insulin delivery system (p<0.001). Our study results highlight the importance of consistent monitoring and adherence to sensor scanning during extreme weather conditions to optimize diabetes management.