DALI: Vitamin D And Lifestyle Intervention for gestational diabetes mellitus (GDM) prevention: a randomised controlled trial
Gestational diabetes
Interventions section as of 09/06/2016: The design is that of two trials with a factorial design: Trial 1: 1. Physical activity (PA) 2. Diet 3. PA & diet 4. Control Trial 2: 1. Vitamin D 2. PA & diet and placebo 3. Vitamin D & PA & diet 4. Placebo In each of the lifestyle interventions (physical activity, diet or a combination of these two), women will have personal contact with the lifestyle coach as soon as possible after randomisation. The same coach will deliver the nutrition and/or physical activity interventions. Each coach will have a desk-file outlining the intervention and options in detail. The first phase of behaviour change for both physical activity and diet is centred around intention formation. Education on risks and benefits, enhancing positive outcome expectancies and self-efficacy beliefs will be the primary task, translating into goal setting, action planning and reinforcement. Following realistic goal setting, the women need to be encouraged and supported in their efforts to eat healthy and/or to be sufficiently physically active. During this action phase behavioural strategies will be provided (e.g. cueing, mental imaging, self-monitoring) along with mobilising social support and identifying and overcoming obstacles where possible. The support programme builds on patient empowerment and cognitive behavioural principles, utilising techniques from Motivational Interviewing. In the programme, one-to-one contact will be offered, along with telephone booster calls. The same amount of time will be offered to each participant during the trial. The intervention will be provided in five sessions of approximately 30-45 minutes, and in four telephone calls of approximately 20 minutes. The on-to-one sessions will take place at the home of the participants or in hospital/midwife practice/general practice, depending on cultural acceptability of home visits. In the Vitamin D intervention, women will use 1600 IU vitamin D supplements per day from the
1. Pre-pregnancy body mass index (BMI) (self-reported weight, measured height) is >= 29 kg/m2) 2. Aged 18 years or more 3. Gestational age at recruitment < 12 weeks 4. Sufficiently fluent in major language of the country of recruitment 5. Being able to be moderately physically active 6. Giving written informed consent 7. Agree to give birth in one of the participating hospitals
1. Pre-existing diabetes 2. Diagnosed with (gestational) diabetes mellitus before randomisation, defined as fasting glucose ≥ 5.1 mmol/l and/or 1 hour glucose ≥ 10 mmol/l and/or 2 hour glucose ≥ 8.5 mmol/l at baseline 3. Not able to walk at least 100 meters safely 4. Requirement for complex diets 5. Advanced chronic conditions (eg valvular heart disease) 6. Sgnificant psychiatric disease 7. Unable to speak major language of the country of recruitment fluently 8. Known abnormal calcium metabolism (hypo/hyperparathyroidism, nephrolithiasis, hypercalciuria) or hypercalciuria detected at screening (0.6 mmol/mmol creatinine in spot morning urine) 9. Twin pregnancy