Aims/hypothesis <p>People with type 1 diabetes are recommended to modify insulin dosing and/or carbohydrate intake before, during and after exercise to manage blood glucose levels and prevent hypoglycaemia. An exercise strategy that produces a more consistent glycaemic response may facilitate glycaemic management around exercise, thereby reducing barriers to exercise related to blood glucose concentration, such as fear of hypoglycaemia, for people with type 1 diabetes. The aim of this study was to compare the consistency of the glycaemic response to resistance exercise performed in the morning while fasted vs in the afternoon after eating.</p> Methods <p>Twelve adults with type 1 diabetes, HbA_1c &lt;85 mmol/mol (10.0%), aged 18–55 years and without contraindications to resistance exercise completed six identical resistance exercise sessions, three in the morning while fasted (AM-FAST) and three in the afternoon in a fed state (PM-FED). The six sessions were completed in a random order in an unblinded, crossover trial, supervised at the Physical Activity and Diabetes Laboratory at the University of Alberta. We compared the within-participant standard deviation (wpSD) of the capillary blood glucose response to AM-FAST vs PM-FED sessions. Capillary glucose was measured pre-exercise, immediately post exercise and 30 min after exercise. Continuous glucose monitoring data were analysed from immediately post exercise up to 24 h after exercise.</p> Results <p>The wpSD of the change in capillary glucose during exercise was lower for AM-FAST (1.0±1.1 mmol/l) than PM-FED (1.5±1.0 mmol/l; <i>p</i>=0.029). There was no difference in the wpSD between conditions during the subsequent 30 min seated recovery (<i>p</i>=0.76). During exercise capillary glucose increased by 1.4±1.9 mmol/l for AM-FAST and decreased by 0.9±2.3 mmol/l for PM-FED (<i>p</i>=0.017). There was a greater percentage of time in hyperglycaemia in the 6 h post-exercise period following AM-FAST vs PM-FED (56.7% [27.2, 67.9] vs 33.0% [22.6, 41.5]; <i>p</i>=0.003, respectively).</p> Conclusions/interpretation <p>The glycaemic response to AM-FAST was more consistent and characterised by increases in glucose concentration, whereas the glycaemic response to PM-FED was less consistent and produced decreases in glucose concentration. Performing resistance exercise while fasted may reduce barriers to exercise for people with type 1 diabetes due to a more consistent glycaemic response that is less likely to cause hypoglycaemia during exercise.</p> Trial registration <p>ClinicalTrials.gov NCT05168488.</p> Funding <p>Dexcom Canada provided in-kind funding in the form of Dexcom G6 transmitters, sensors and receivers. LifeScan Canada provided in-kind funding in capillary glucose testing strips. JEY was supported by a Heart and Stroke Foundation of Canada Alberta New Investigator Award.</p> Graphical Abstract <p></p>