Can non-responders be ‘rescued’ by increasing exercise intensity? A quasi-experimental trial of individual responses among humans living with pre-diabetes or type 2 diabetes mellitus in Canada

Introduction Exercise is recommended to improve glycaemic control. Yet, individual changes in glycaemic control following exercise can vary greatly, meaning while some significantly improve others, coined ‘non-responders’, do not. Increasing the intensity of exercise may ‘rescue’ non-responders and help generate a response to training. This trial will identify non-responders to changes in glycated haemoglobin (HbA1c) across inactive individuals living with pre-diabetes or type 2 diabetes mellitus following an aerobic exercise programme and evaluate if increasing training intensity will elicit beneficial changes to ‘rescue’ previously categorised non-responders. Methods and analysis This study will recruit 60 participants for a two-phase aerobic exercise training programme. Participants will be allocated to a control group or assigned to an intervention group. Control participants will maintain their current lifestyle habits. During phase 1, intervention participants will complete 16 weeks of aerobic exercise at an intensity of 4.5 metabolic equivalents (METs) for 150 min per week. Participants will then be categorised as responders or non-responders based on the change in HbA1c. For phase 2, participants will be blocked based on responder status and randomly allocated to a maintained intensity, or increased intensity group for 12 weeks. The maintained group will continue to train at 4.5 METs, while the increased intensity group will train at 6.0 METs for 150 min per week. Ethics and dissemination Results will be presented at scientific meetings and submitted to peer-reviewed journals. Publications and presentations related to the study will be authorised and reviewed by all investigators. Findings from this study will be used to provide support for future randomised control trials. All experimental procedures have been approved by the Research Ethics Board at the University of New Brunswick (REB: 2018–168). Trial registration number NCT03787836.