Study examining the effects of altering a diet's macronutrient composition on plasma ketone levels in women with gestational diabetes mellitus

Arm 1 Intervention - Main focus will be limiting daily carbohydrate intake to 135 g. Carbohydrates should be spread evenly through out the day, with 2 carbohydrate exchanges per main meal (3 times a day) and 1 exchange per mid meal (also 3 times a day). One exchange equals to consuming 15 g of carbohydrate and this proves to be a useful method of monitoring carbohydrate intake, particularly in individuals diagnosed with diabetes. A research dietitian will have ongoing contact with participants via phone (to arrange meetings) and during 4 face-to-face sessions (including a baseline and 3 other follow up visits in Week 2, Week 4 and Week 6, all lasting no more than an hour). To prevent study bias, participants will be unaware of their group allocation. They will, however, receive a pictorial booklet containing acceptable carbohydrate portions of various foods. The study dietitian will also verbally guide participants on the acceptable amount and distribution of carbohydrates . A 3-day food record will be collected at baseline and in the last (6th or 7th) week of the study, where as a 24 hour recall will be conducted at 2 follow up visits to confirm diet compliance. Non-compliant participants will be re-educated. Food packages including breads, cereals, pasta and rice will be handed to women to help model portion size (i.e. what represents 1 exchange) and enhance participation rate. The study is designed to last 6-7weeks (though 6 ideally), but this will depend on participant's availability and ability to attend all the face-to-face sessions.