Manchester Intermittent and Daily Diet Type 1 Diabetes App Study (MIDDAS-Type 1)

Inclusion Criteria:

• T1D for 12 months or longer
• HbA1c 53-108 mmol/mol
• BMI ≥ 30 kg/m2 and <50kg/ m2 or ≥27.5 kg/ m2 and <50kg/ m2 in high-risk minorityethnic groups i.e. South Asian, Black African and African Caribbean
• Multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII)
• Completed Dose Adjustment For Normal Eating (DAFNE) education
• Access to a Freestyle Libre handset and sensors to monitor blood glucose
• Willing to use the Freestyle Libre® flash glucose monitoring system to monitor bloodglucose (flash and capillary) and blood ketones and to record carbohydrate andinsulin.
• Access to and ability to use a telephone. If no access to a smartphone running iOS orAndroid (to view the LibreLink app®) then access to a computer (to upload results tothe LibreView website).
• Willing to undertake Optifast® LEDs and have previously sampled Optifast®.
• Negative urine pregnancy test at screening and agreement to maintain contraception orabstinence for the trial (where appropriate)
• Ability to read, understand and communicate in English.

Exclusion Criteria:

• Evidence of severe hypoglycaemia in the last 12 months (more than one episoderequiring third party assistance) or hypoglycaemia unawareness.
• Patients with non-stable retinopathy, or grade R2 or later, or had no retinopathyscreen within 12 months.
• Patients who lack capacity or are unable to read or understand written or verbalinstructions in English or those diagnosed with learning difficulties.
• Confirmed pregnant via a pregnancy test at screening, planning pregnancy in the next 3months, or currently breast feeding.
• Participants who are currently on treatment with Orlistat or other pharmacologicaltreatments for weight loss e.g. Glucagon-like-peptide-1 (GLP-1).
• Participants who are currently taking a Sodium-Glucose Co-Transporter-2 (SGLT2)inhibitor.
• Diagnosed Gastroparesis.
• Participants who have previously had bariatric surgery for weight loss includinggastric bypass and sleeve gastrectomy.
• Patients who are on chronic use of steroids (more than 20mg daily of prednisolone orits equivalent).
• Patients with known hypersensitivity to any of the ingredients of Optifast® e.g. fish,milk, soy.
• Taking prohibited medications (see Appendix 3) including warfarin or novelanticoagulants (NOAC), low molecular weight heparin (LMWH) or equivalentanti-coagulants and anti-psychotic medication or other psychotropic medications thatmay cause excessive weight gain.
• Substance abuse or harmful alcohol use as indicated by a score of 16 or above on theAlcohol Use Disorders Identification Test (AUDIT).[36]
• Participants with a diagnosed eating disorder, or patients with severe binge eatingassessed by a score of 27 or more on the Binge Eating Scale (BES).[37]
• Participants with severe depression assessed by a score of 15 or more on the PatientHealth Questionnaire-9 (PHQ-9) questionnaire.[29]
• Participants with severe anxiety assessed by a score of 15 or more on the GeneralAnxiety Disorder (GAD-7) questionnaire.[28]
• Participants with very low self-efficacy assessed by a score of 35 or less on theWeight Efficacy Lifestyle Questionnaire (WEL-SF).[30]
• Participants with severe loss of renal function (eGFR < 30mL/min/1.73m2).
• Participants with psychiatric or physical comorbidity or scheduled for major surgery,which in the opinion of the treating medical physician, Chief Investigator (CI) orMultidisciplinary Team (MDT) would compromise their safety or adherence to the study.
• Unsatisfactory use of the Freestyle Libre® flash glucose monitoring system or unsafeuse of DAFNE/insulin adjustment principles during the 14-day "run-in" period that inthe opinion of the medical team may undermine the participant's safety on the trial.This includes flash and capillary monitoring of blood glucose and ketone testing.
• Patients who are currently participating in a diabetes drug trial.