Optimising self-management in youth with type 1 diabetes to improve short-term glycaemic control: OPTIMISE Study

Participants will be randomised to one of 16 experimental groups comprised of a 4-week 'no intervention' phase or up to four 4-week interventions that are delivered during the same 4-week intervention phase (i.e., a participant randomised 'Yes' to all candidate components will receive all four interventions within a single 4-week intervention phase). Delivery will be 1-to-1. Adherence to the intervention will be assessed via self-report on the study exit evaluation questionnaire. Continuous glucose monitoring (CGM): A Dexcom G6 transmitter and 4 Dexcom G6 sensors will be provided at the baseline study visit (intervention education duration - approximately 30 minutes). Participants will wear the interstitial glucose sensors per manufacturer's guidelines (on their abdomen, buttocks, upper arm). The sensor does not require calibration. Sensors are changed every 10 days. A trained research nurse will provide education on using the G6 for glucose monitoring based on the manufacturer's guidelines, supervise the first sensor being applied by the participant, and sync the glucose readings to the Dexcom G6 app on a personal smartphone. All CGM systems will be synced to Dexcom Clarity, a password-protected website for accessing CGM data. Participants' glucose patterns will be reviewed at the 14-day follow-up visit (intervention education duration - approximately 15 minutes). If time in range (sensor glucose values 3.9-10.0 mmol/L) is <70% then the CGM system low and high alert settings may be adjusted to encourage action to treat out-of-range levels. Participants in this study group will be required to wear both a Dexcom G6 sensor and a FreeStyle Libre Pro sensor during the final 2 weeks of the intervention phase. Sleep extension: All participants will receive sleep hygiene education from a trained research nurse at the baseline visit (education duration - approximately 15 minutes). The sleep hygiene educational materials were developed for New Zealand adolescents in an unrelated study and are being used with permission. At the baseline visit (intervention duration - approximately 5 minutes), those who are allocated 'Yes' to sleep extension will be asked to go to bed one hour earlier than their usual bedtime on weekdays and weekends (as determined by their baseline median “lights out” time on weekdays and weekends collected via self-report) each night for the remaining trial duration while maintaining their usual wake up time. A follow-up will be conducted at the 14-day visit to assess progress towards achieving an extra hour of sleep each night and revising sleep extension to 45 minutes or 30 minutes if having difficulty achieving a full hour of sleep extension (intervention duration approximately 15 minutes). Participants will not be provided with a device that provides them with feedback on their sleep activity. Snacking education and goalsetting: At the baseline visit (intervention duration - approximately 15 minutes), a trained research nurse will provide practical snacking education, including a handout of healthy snack options and the importance of timing and frequency of snacks to avoid grazing. Educational materials provided have been adapted for the New Zealand context from "Snacking 101: An explainer for people living with T1D"(https://jdrf.org.au/snacking-101-an-explainer-for-people-living-with-t1d/) with permission. Participants will select a snacking-specific behaviour to change and set a goal to achieve the change during the 4-week intervention phase. A follow-up will be conducted at the 14-day visit to assess progress towards completing the goal and revising the goal as needed (intervention duration approximately 15 minutes). Participants will not be provided with a food diary to track their progress towards their goal. Values-guided self-management: a research fellow trained in Acceptance and Commitment Therapy will meet with participants allocated 'Yes' to this candidate component for a single 30-60 minute session in person or via freely available teleconference software (Zoom) within one week of the baseline visit. The session will focus on identifying what matters to the participant (their values), how diabetes has been an obstacle to valued-living, and setting a goal to change one diabetes-specific behaviour that cultivates valued-living. Barriers to achieving the goal will be explored, with mindfulness and acceptance strategies taught to overcome challenges as relevant. A follow-up will be conducted at the 14-day visit to assess progress towards completing the goal and revising the goal as needed (intervention duration approximately 15 minutes).