Determining the Effect of Food Ordering on Blood Glucose In Gestational Diabetes Mellitus (DEFI-GDM) - a Randomised Crossover Study

Gestational diabetes mellitus (GDM) is glucose intolerance with onset or first diagnosis during pregnancy, affecting around 1 in 10 pregnancies in the United Kingdom (UK). Women with GDM are 10 times more likely to develop type 2 DM and twice as likely to develop cardiovascular disease in later life than women without GDM. Dietary modification is recommended as first line management to optimise blood glucose control. However, this often fails, necessitating the use of medication such as metformin and insulin. There is a pressing need to find safe and effective dietary approaches to optimise glycaemic control in GDM which can be easily adhered to in order to improve longer-term outcomes. The impact of the sequence of macronutrients on glycaemic control is an emerging area of interest. Recent evidence suggests that the consumption of the fat/protein components of a meal prior to the carbohydrate components, reduces the peak by around 40% after food. This study aims to determine whether the order that macronutrients (i.e. protein, fat, carbohydrate) are eaten affects; blood sugar glucose levels in the blood after a meal, appetite, food intake and the release of hormones in the body, in women with GDM.

Pregnant women with GDM, aged 18-50 years old who are between 24-37 weeks pregnant are eligible for the study. Women are not eligible if they have a history of type 1 or 2 diabetes, any clinically confirmed food allergies, taking medication for GDM at point of study entry, severe nausea, using anti-sickness medication or any other problems that would substantially limit ability to complete study requirements.

Recruitment will be via antenatal clinics in the South-Eastern Health and Social Care Trust (SEHSCT) and also via social media. Participants will attend the Centre for Public Health on two occasions (maximum 2 weeks between visits) and will involve the collection of demographic information, weight and height measurements, blood samples, glucose measurements, consumption of study breakfast, and completion of two 1-day food diaries.

Participants will be asked to eat either the protein/fat-based component of the meal (scrambled egg) before or after the carbohydrate-based component (wholemeal toast) on their first visit and on the other visit they will be asked to eat the meal in the reverse order. The order in which this occurs will be randomised and each participant will act as their own control. Scrambled egg was chosen as the protein and fat will be homogenously distributed (compared to boiled egg, for example). Wholemeal toast was chosen as, although lower glycaemic index and therefore less likely to expeditiously raise blood glucose than toasted white bread, it will be more consistent with the participants' existing dietary needs.