What Or When to Eat to Reduce the Risk of Type 2 Diabetes (WOW)

A parallel, single-blinded, multi-centre randomized controlled trial conducted at the South Australian Health and Medical Research Institute (SAHMRI) and the Mary Mackillop Institute for Health Research (MMIHR; Australian Catholic University), by researchers from the University of Adelaide, Australian Catholic University and La Trobe University.

In a parallel groups design, a total of 268 individuals will be recruited across both sites. After a 2-week baseline period, and a baseline metabolic visit, participants will be randomized into one of two groups (TRE, time-restricted eating; CP, current practice guidelines). All participants will receive five (5) telehealth consultations at baseline, week 2, 4, 8 and 12, the content of which will be based around their randomized condition. They will undergo metabolic testing on two (2) further occasions (4 months, 12 months) over a 12-month period to assess the changes in primary and secondary outcomes.

Eligibility Criteria:
Inclusion Criteria:

* Study participants will be aged 35 to 70 years, overweight or obese (BMI: \>25 but \<45 kg/m2), ≥15 on the AUSDRISK assessment tool and have HbA1c \<6.5% at screening

Exclusion Criteria:

Type 1 or type 2 diabetes, or diabetes detected at screening HbA1c ≥6.5% (48 mmol/mol).

* A personal history/diagnosis (self-reported) of:

  * major psychiatric disorders (schizophrenia, major depressive disorder, bipolar disorder, eating disorders)
  * gastrointestinal disorders/disease (including malabsorption)
  * haematological disorders (i.e. thalassemia, iron-deficiency anaemia)
  * insomnia
  * currently receiving, or have received treatment/diagnosis of cancer in the past 3 years (excluding non-melanoma skin cancer)
  * significant liver or kidney disease
  * previous or planned gastro-intestinal surgery (including bariatric surgery)
  * Congestive heart failure (NYHA stage 2 or above)
  * Previous myocardial infarction or significant cardiac event ≤ 6 months prior to screening
  * Previous cerebrovascular event ≤ 12 months prior to screening

and/or any other condition deemed unstable by the study physician.

Currently taking the following medications:

* any medication used, or known to lower blood glucose, or antidiabetic medications, including, but not limited to: SGLT2 inhibitors, metformin, sulfonylureas, glucagon-like peptide-1 (GLP-1) analogues \[i.e. exenatide\], thiazolidinediones or DPP-IV inhibitors \[i.e. 'gliptins'\])
* Medications affecting weight, appetite or gut motility, including, but not limited to: (domperidone, cisapride, orlistat, phentermine, topiramate).
* Diuretics (i.e. frusemide, thiazides) or combination blood pressure medications containing a diuretic
* Beta-blockers
* Glucocorticoids
* Anti-epileptic medications
* Antipsychotic medications
* Opioid medications unless combined with paracetamol in a single formulation and used occasionally on a PRN basis

Additional exclusion criteria include:

* do not consume a regular breakfast (i.e. eat breakfast on an average of 5 or more days per week), and do not eat for more than 12 hours per day on an average of 5 or more days per week
* have an extreme or restricted pattern of eating (i.e. following an intermittent fasting diet) or are already engaged in a TRE protocol
* shift-workers
* pregnant, planning a pregnancy or currently breastfeeding
* those who have lost or gained \>5% of body weight in the last 6 months
* current smokers of cigarettes/marijuana/e-cigarettes/vaporisers
* anyone unable to comprehend the study protocol or provide informed consent (i.e. due to English language or cognitive difficulties)
* Participants will not have seen a dietitian in the preceding 3 months.
* score on K10 ≥30 (Kessler Psychological Distress scale)
* score on EDEQ ≥2.8 (Eating Disorder Examination Questionnaire)