Explanatory variables of objectively measured physical activity, sedentary behaviour and sleep in adults with type 1 diabetes: A systematic review

This systematic review aimed to summarize knowledge on explanatory variables of PA, SB and sleep in adults with T1D to support the development of healthy lifestyle interventions. A systematic search of four databases (PubMed, Web of Science, Scopus and Embase) was performed. Only objective measurements of PA, SB and sleep were included and all explanatory variables were classified according to the socio-ecological model (i.e. intrapersonal, interpersonal, environmental and policy level). Risk of bias (ROB) (Joanna Briggs Institute appraisal checklists) and level of evidence (Evidence-Based Guideline Development) were assessed. Twenty-one studies were included (66.7% low ROB). Most explanatory variables were situated at the intrapersonal level. A favourable body composition was associated with more time spent in total PA and moderate-to-vigorous PA (MVPA). Men with T1D spent more time in MVPA than women and a younger age was associated with increased MVPA. Barriers to PA were indeterminately associated with MVPA and HbA1c showed an indeterminate association with sleep. Explanatory variables of SB and light PA were not studied in at least two independent studies. This review underscores the focus on the individual level to identify explanatory variables of movement behaviours in adults with T1D, despite the necessity for a socio-ecological approach to develop effective interventions. More evidence on psychological, interpersonal and environmental variables is needed as these are modifiable.