Outcome
Type |
Measure |
Description |
Time frame |
Safety issue |
Other |
Percentage of participants commencing metformin |
The percentage of women commencing metformin will be measured. |
From 24-30 weeks' gestation until delivery. |
|
Other |
Percentage of participants commencing insulin |
The percentage of women commencing insulin will be measured. |
From 24-30 weeks' gestation until delivery. |
|
Other |
Changes in HbA1c (mmol/mol) |
Bloods will be taken at 27-29 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum. Changes in HbA1c between these time points will be compared within and between groups and expressed in mmol/mol. |
Recorded at 24-30 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum |
|
Other |
Changes in fasting glucose (mmol/L) |
Bloods will be taken at 27-29 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum. Changes in fasting glucose between these time points will be compared within and between groups and expressed in mmol/L. |
Recorded at 24-30 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum |
|
Other |
Changes in fasting insulin (mU/L) |
Bloods will be taken at 27-29 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum. Changes in insulin levels between these time points within and between groups will be compared and expressed in mU/L. |
Recorded at 24-30 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum |
|
Other |
Oral Glucose Tolerance Test (mmol/L) result |
Oral Glucose Tolerance Test (OGTT) will be completed at 11-13 weeks postpartum. Fasting and 2 hour postprandial bloods will be measured and the percentage of women with a diagnosis of residual diabetes according to the World Health Organization (WHO) criteria will be reported in both groups. |
11-13 weeks' postpartum |
|
Other |
Changes in the value of Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) |
HOMA-IR will be calculated from fasting glucose and insulin measurements [(fasting insulin mU/L x fasting glucose nmol/L)/22.5] assessed at 27-29 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum. Changes in HOMA-IR between these time points will be compared within and between groups. |
Recorded at 24-30 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum |
|
Other |
Changes in maternal health status |
Health status (SF-36) questionnaires will be completed in both groups and scores compared both within and between groups. Scores range from 1-100; the lower the score the more the disability, the higher the score the more favourable the health state. |
Recorded at 24-30 weeks' gestation, 31-33 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum |
|
Other |
Changes in maternal quality of life |
Quality of life (WHOQoL-BREF) questionnaires will be completed in both groups and scores compared both within and between groups. This questionnaire measures four domains (physical health, psychological, social relationships and environment). Final scores range between 1-100; higher scores indicate a higher quality of life. |
Recorded at 24-30 weeks' gestation, 31-33 weeks' gestation, 36-37 weeks' gestation, and at 12-13 weeks postpartum |
|
Other |
Changes in maternal glycaemic control |
Four-point capillary glucose profiles (four times daily) between 27-29 weeks' gestation and delivery will be compared within and between groups. The percentage of women within target ranges will be reported within and between groups (fasting <5.3 and 1 hour postprandial <7.8 mmol/l). |
From 24-30 weeks' gestation until delivery |
|
Other |
Mode of delivery |
Mode of delivery will be recorded in both groups |
At delivery |
|
Primary |
Trial recruitment rate |
Uptake to trial will be measured as a percentage of eligible participants who consent to participate in the trial per month. |
Duration of trial (68 weeks) |
|
Primary |
Retention to the trial |
Retention rate will be measured as the percentage of participants who complete all scheduled 8 visits. |
Duration of trial (68 weeks) |
|
Primary |
Trial uptake |
Trial uptake will be measured as the percentage of eligible participants who consent to participate in the trial. |
Duration of trial (68 weeks) |
|
Primary |
Adherence to the interventional intermittent low-calorie diet over course of study |
Self-reported adherence to the two potential low-calorie days per week expressed as a percentage of the potential low-calorie days in the intermittent low energy diet group. |
From randomisation (at 24-30 weeks' gestation) to delivery. |
|
Primary |
Adherence to capillary glucose and ketone measurements over course of study |
The number of self-assessed glucose (4 times a day) and ketone (3 times a day on two days of the week) measurements in both groups over the course of the study. |
From randomisation (at 24-30 weeks' gestation) to delivery |
|
Primary |
Episodes of hypoglycaemia requiring intervention |
The percentage of women with self-reported hypoglycaemia (capillary blood glucose of <3.0 mmol/l) will be measured and compared between groups. |
From 24-30 weeks' gestation until delivery. |
|
Primary |
Episodes of ketonaemia requiring intervention |
The percentage of women with self-reported significant ketonaemia (capillary ketones >1 mmol/l) will be measured and compared between groups. |
From 24-30 weeks' gestation until delivery. |
|
Primary |
Rates of neonatal hyperbilirubinaemia/jaundice |
Percentage of neonatal hyperbilirubinaemia/jaundice (defined as a total serum bilirubin level above 86 µmol/l) episodes will be recorded in both groups. |
From delivery until final visit at 12-13 weeks' postpartum |
|
Primary |
Rates of neonatal hypoglycaemia |
Percentage of neonatal hypoglycaemic episodes requiring intervention (blood glucose checked 2-hours post delivery and 2-hours thereafter for 12 hours) will be recorded in both groups. |
From delivery until 12 hours post-delivery |
|
Primary |
Neonatal birthweight |
Neonatal birth weight will be measured in kilograms and recorded in both groups. |
At delivery |
|
Primary |
Neonatal gestational age at delivery |
Gestational age at delivery will be measured in weeks and recorded in both groups. |
At delivery |
|
Primary |
Gestational age at delivery |
Gestational age at delivery in weeks will be recorded in both groups. |
At delivery |
|
Primary |
Rates of admission to special care baby unit or neonatal intensive care |
Rates of admission to Special Care Baby Unit or Neonatal Intensive Care will be recorded in both groups. |
From delivery until final visit at 12-13 weeks' postpartum |
|
Primary |
Number of stillbirths |
Number of stillbirths will be recorded in both groups. |
At delivery |
|
Secondary |
Number of completed scheduled patient contacts |
Completion of scheduled patient contacts with the trial dietitian and gestational diabetes midwife will be recorded and compared between groups. |
Duration of trial (68 weeks) |
|
Secondary |
Completion rates of food diaries |
Participants will be asked to complete 4-day food diaries for 4 weeks of the trial at 24-28 weeks' gestation, 34-35 weeks' gestation, 36-37 weeks' gestation, and 12-13 weeks postpartum. They will also be given the option of recording diaries during the other weeks as this may help with their adherence. Completion rates of the food diaries each week across the whole intervention as a percentage of weeks in both groups will inform the utility of food diaries for tracking diet behaviour in both groups |
4 day food diaries at 24-30 weeks' gestation, 34-35 weeks' gestation, 36-37 weeks' gestation, and 12-13 weeks postpartum. |
|
Secondary |
Completion rates of International Physical Activity Questionnaire (IPAQ) |
Participants will be asked to complete the IPAQ during 4 weeks of the trial at 24-28 weeks' gestation, 34-35 weeks' gestation, 36-37 weeks' gestation, and 12-13 weeks postpartum. Completion rates will be measured as a percentage of weeks completed in both groups. |
IPAQ questionnaire at 24-30 weeks' gestation, 34-35 weeks' gestation, 36-37 weeks' gestation, and 12-13 weeks postpartum. |
|
Secondary |
The acceptability of the dietary interventions will be explored qualitatively |
A subset of participants in both groups (approximately 5 participants from each group) will be invited to an optional qualitative substudy which will involve one semi-structured interview at the end of the intervention. Participants will be asked about their experiences and thoughts regarding the intervention. Key themes will be identified using Braun and Clarke's thematic analysis to identify key issues around the acceptability of the test intervention. |
12-13 weeks' postpartum |
|