Title: Effect of an intermittent low energy diet on glycaemic control and the requirement for anti-diabetic medication in women with gestational diabetes: a feasibility study.
Funder: Department of Health and Social Care

Abstract: Research question: To study the feasibility and acceptability and safety of an intermittent low-energy diet (ILED) in women with gestational diabetes (GDM). Also the feasibility of a randomised controlled trial (RCT) of ILED compared to best NHS care in these women. Background: Up to 16% of pregnant women in the UK develop GDM with rising rates due to increasing rates of obesity and maternal age. GDM affects both maternal and neonatal outcomes and is a high burden to patients and the NHS through frequent clinic visits, monitoring, and costly medications such as insulin. NICE guidelines advocate healthy diet (with increased physical activity [PA]) as first-line therapy for GDM with approximately 30% progressing to metformin and/or insulin treatment. Women with GDM are keen for alternative dietary interventions to reduce their need for medications. We and others have shown that intermittent low energy diets improve glycaemic control in type-2 diabetes. We wish to test the utility of ILED in GDM Aims: To explore the feasibility of using an ILED in the management of GDM with the objective of conducting a large, statistically powered RCT of ILED vs. best NHS care. Primary Objectives of the feasibility study: 1. Uptake, recruitment rate and retention to a RCT of ILED vs. best NHS care 2. Adherence to dietary allocation within the ILED and best NHS care groups. 3. Safety outcomes with ILED including episodes of maternal hypoglycaemia or ketonaemia 4. The suitability of progression to medication as a suitable endpoint for a future definitive study. Methods: Phase 1: We will co-design patient dietary and study information with a patient public involvement (PPIE) panel of women with experience of GDM . Phase 2: 48 women diagnosed with GDM and obesity (BMI &ge;30 Kg/m2) will be randomized 1:1 to an ILED and PA intervention or best NHS Care (healthy diet and PA) for the third trimester of pregnancy. Both groups will receive the relevant diet and PA advice and fortnightly phone support by the study dietician until delivery. They will also undergo standard maternal and foetal assessments at baseline, delivery and 12 weeks post-delivery including weight and maternal metabolic parameters. Adherence to the diet and PA will be assessed using food records and a diet quality and PA questionnaires. The percentage of women in each group requiring metformin and/or insulin, and differences in capillary glucose profiles, HbA1c, insulin, c-peptide and HOMA-IR between the two groups will be analysed. Phase 3: We will undertake qualitative analysis of the experiences and thoughts of 5 participants per group and healthcare professionals delivering the interventions. Timelines: 5 months set -up and co-design of patient materials; 15 months feasibility study; 6 months analysis dissemination and preparing definitive trial application if feasible. Anticipated impact and dissemination: this study will inform the feasibility and design of a definitive RCT of ILED versus best NHS care in GDM. Findings will be disseminated to health professionals and patients through published articles, conference presentations and patient networks in collaboration with our PPIE panel.

Lay abstract: Aim of Research Gestational diabetes (GDM) causes risks to mother and baby from high blood sugar, high blood pressure, induced labours, caesarean-sections, and larger babies. Women often need medication to control blood sugar. Intermittent low-calorie diets,on two days of the week improve blood sugar control in Type 2 diabetes (T2D) and reduce need for medication. This study aims to find out if an intermittent low-calorie diet is acceptable to women with GDM and to make sure it is safe before carrying out a larger study. We also want to find out whether this diet might also improve blood sugar control in GDM as this is a similar condition to T2D. Background Research There is no good evidence for the best diet to manage GDM. Daily low-calorie diets are not recommended as they can reduce babies growth and women find these diets difficult to follow. Our research shows that women find current dietary advice in GDM to be confusing, and importantly, that women would be motivated to change their diet to try to avoid the need for medication, and to improve their own and their baby s health. Design and Methods Used Research will be carried out in three phases. Phase 1 will develop patient dietary resources and study information guided by women with experience of GDM. Phase 2 will recruit 48 women diagnosed with GDM at 24-28 weeks pregnant. Women will be allocated randomly by a computer to a group which receives best NHS care and general advice on a healthy diet or a group which is asked to follow the intermittent low (1000 Kcal/day) calorie diet on two days of the week until delivery. Both groups receive fortnightly contact with the dietitian. We will assess the numbers who join, stay engaged with the study and whether they can follow the intermittent diet. The safety of mother (e.g. mothers blood sugars and other blood parameters) and baby (e.g. babies blood sugars after birth) will be closely monitored throughout the study. We will assess changes in weight, blood sugar, blood pressure, blood tests changes and the need for medications. Phase 3 will explore the thoughts and experiences of women taking part and also health care professionals delivering the intervention. This study will tell us whether intermittent diets are feasible and safe and tell us ways to improve the diet to make it more acceptable to women with GDM. Also, whether we should proceed to a larger study to test whether they are better than standard current dietary management of GDM.

Research activity codes: 6.7 PHYSICAL
Health categories: REPRODUCTIVE HEALTH AND CHILDBIRTH;METABOLIC AND ENDOCRINE