None listed
Conditions
Brief summary
Appropriate nutrition is a cornerstone of type 2 diabetes management guidelines internationally. Dietary strategies which improve glucose control may prevent or delay the onset of diabetes-related complications including neuropathy, nephropathy, and retinopathy. Partial meal replacement and time-restricted eating are each dietary strategies which may lead to meaningful improvements in glucose control for people with type 2 diabetes. These interventions are also two very different approaches: one uses formula meal replacements to limit energy intake, while the other is primarily focused on changing meal timing rather than the quantity or quality of intake. As such, one intervention may be more (or less) acceptable than the other for different people and for different reasons. In this study we will consider the effect of these two dietary interventions on blood glucose control in 30 people with type 2 diabetes. In the time-restricted eating intervention, participants will consume their usual foods within a chosen 9- hour eating window (e.g. 8am-5pm or 10am-7pm). In the partial diet replacement intervention, participants will replace 2 of their usual meals with low-energy formula meal replacement products supplied by us. This is a crossover study, meaning participants will take part in both interventions for a period of 2 weeks each, separated by a 'washout period' (i.e. returning to normal eating patterns) of at least 2 weeks. We will quantify and compare the effects of these two interventions on glucose control, and conduct interviews to explore intervention acceptability and understand participants' experiences within the study. Our research questions are: among people with type 2 diabetes, which of these two dietary strategies (time-restricted eating or partial diet replacement) is more effective in improving glucose control, and which is more acceptable? While we hypothesise that both dietary interventions will result in improved glucose control, we expect that the acceptability of each intervention will vary depending on a number of individual and social factors.
Interventions
This study consists of two separate dietary interventions (time-restricted eating and partial diet replacement), each lasting two weeks. These will be preceded by a two-week period of baseline monitoring and separated by a minimum two-week washout period. During each of the baseline monitoring and washout periods, participants will be asked to adhere to their usual eating habits, with no further lifestyle advice provided. Participants will wear a continuous glucose monitoring (CGM) sensor to ass
This study consists of two separate dietary interventions (time-restricted eating and partial diet replacement), each lasting two weeks. These will be preceded by a two-week period of baseline monitoring and separated by a minimum two-week washout period. During each of the baseline monitoring and washout periods, participants will be asked to adhere to their usual eating habits, with no further lifestyle advice provided. Participants will wear a continuous glucose monitoring (CGM) sensor to assess glycaemic control during the two-week baseline monitoring period and each of the two-week dietary interventions. Throughout the duration of the study, participants will be asked to maintain their usual physical activity levels and will continue to receive usual care through their general practice. Interventions will be delivered by a member of the research team via five individual, face-to-face study visits held at baseline and before and after each two-week dietary intervention. Participants will also have an initial Zoom/phone call/in-person visit to assess eligibility and provide study information. ‘Check ins’ and additional support (if required) will be available via text, phone call, or email between visits. The expected duration of participation is eight weeks (longer if the participant requires additional time between visits and/or a washout period longer than two weeks). Study visits will be held in a local hospital/clinical/office space and are expected to last 30–60 minutes each. Study visits will include (as appropriate) administering the interventions, providing participants with required resources (e.g. meal replacement products; adherence checklists); application/removal of CGM sensors; data collection (e.g. weight; blood pressure; questionnaires; qualitative interviews); and post-intervention review of adherence checklists, diet records, and reported side effects. After completing both interventions, participants will be offered an optional in-person review of their continuous glucose monitoring results and (if appropriate) self-reported dietary intakes. This may include individualised nutrition education and advice. This review may take place during the final study visit or at a later date. Time-restricted eating intervention: In the time-restricted eating intervention, participants will be asked to maintain their usual food choices but to restrict their intake of all food and energy-containing beverages (e.g., tea/coffee with milk) to a self-selected 9-hour window ending no later than 7:00pm. No further dietary advice (e.g. food choice, portion size, diet quality, or meal timing within window) will be provided. Participants will be asked to adhere to the same self-selected eating window on as many days as possible during the entire two-week time-restricted eating intervention. For example, participants may choose to consume all food and energy-containing beverages between 10:00am and 7:00pm each day for two weeks, or between 8:45am and 5:45pm each day for two weeks. Participants may freely consume non-nutritive beverages (i.e., water, plain tea, black coffee, and zero-energy/diet drinks) throughout the intervention. Intervention adherence will be assessed using a three-day diet record (on paper or app-based) and a daily adherence checklist (including the time of the first and last eating occasion). These will be completed by participants and checked for accuracy at the next study visit. Partial diet replacement intervention: In the partial diet replacement intervention, participants will be asked to maintain their usual food choices, except for replacing any two main meals per day with the meal replacement products we provide. Participants will be asked to adhere to this approach on as many days as possible throughout the entire two-week partial diet replacement intervention, but the timing of meal/meal replacement consumption needn’t be the same each day. For example, participants might choose to consume meal replacements at breakfast and lunch with a ‘real food’ dinner on Day 1, followed by meal replacements at breakfast and dinner with a ‘real food’ lunch on Day 2. Meal replacement products (Cambridge Weight Plan Ltd., Corby, Northants, UK) will be provided free of charge, and a variety of options (e.g., shakes, soups, bars, porridges, and meals) and flavours will be available. Each meal replacement product has an energy content of approximately 850 kJ (~200 kcal). Participants may freely consume non-nutritive beverages (i.e., water, plain tea, black coffee, and zero-energy/diet drinks) throughout the intervention. Intervention adherence will be assessed using a three-day diet record (on paper or app-based) and a daily adherence checklist (including the number of meal replacements and real-food meals consumed). These will be completed by participants and checked for accuracy at the next study visit.
Sponsors
Dr Andrew Reynolds, University of Otago, Aotearoa New Zealand
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Eligibility
Sex/Gender
All
Age
18 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
Participants will be aged 18–80 years, with overweight or obesity and medically-diagnosed type 2 diabetes. Participants must be willing to participate in both dietary interventions for a period of two weeks each (including consuming meal replacement products which may contain milk/dairy and/or gluten) and be willing to wear only a blinded CGM sensor (i.e., not wear a CGM for personal use) for up to six weeks in total.
Exclusion criteria
• Not weight stable (i.e., >5 kg change in body weight in the previous 3 months) • Doctor-prescribed change to glucose-lowering or anti-obesity medications in the last 3 months • Current insulin use • Previous weight loss surgery • Night shift worker (i.e., working >3 hours between 10pm and 5am at least once per week in the previous 3 months or over the study duration) • Myocardial infarction in the last three months • Currently receiving cancer treatment • Diagnosed or self-reported eating disorder • Pregnancy or lactation (current or planned over the study duration). Eligibility may also be affected by prescribed medications which increase the risk of hypoglycaemia (e.g., sulfonylureas) or which must be taken with food in the early morning or late evening (i.e., outside the time-restricted eating window). Food allergies or intolerances may also limit the variety of meal replacement products suitable for some individuals. These issues will be discussed with participants and the appropriate health professional on a case-by-case basis.
Outcome results
None listed