Condition category
Nutritional, Metabolic, Endocrine
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Gestational Diabetes Mellitus (GDM) is a heath condition that occurs during pregnancy where the body becomes unable to produce enough insulin – a hormone that helps to control the amount of sugar in the blood – to meet the extra needs during pregnancy. The condition usually resolves itself after the mother has given birth. There is growing interest in GDM due to an increase in the number of women being diagnosed with the condition. It can have harmful consequences for both mother and baby. The mother, for example, can develop gestational hypertension (high blood pressure) and pre-eclampsia (a condition that causes high blood pressure and can lead to some serious pregnancy complications if left untreated). GDM can also the baby to grow larger than usual (macrosomia) , which can result in a difficult delivery and the need for induced labour or caesarean section, low blood sugar levels (hypoglycemia), high insulin levels (hyperinsulinemia) shoulder dystocia (a condition where it is difficult to deliver the shoulders of the baby after the head has already been delivered), and an increased risk of obesity (being very overweight) and type 2 diabetes later in life. A significant number of women who have had GDM will develop type 2 diabetes later in life and may be at increased risk of cardiovascular (for example heart) disease. Researchers have looked at the effect of the Mediterranean diet on the prevention of GDM, providing free olive oil and nuts to patients (study record ISRCTN84389045). There is some preliminary data showing a decrease in the number of women developing GDM after eating a Mediterranean diet(with recommendations of reducing fat intake to < 30% and saturated fat < 10% of total intake). This study is looking at whether an universal nutritional recommendation based on the Mediterranean diet in the real clinical setting (for example, a hospital) , with the usual obstetric and endocrinological follow-up will be as effective as when tested as part of a clinical study.

Who can participate?
Pregnant women over the age of 18 with high blood glucose levels.

What does the study involve?
All participants are given advise on diet to be followed during their pregnancy. Recommendations include having fresh vegetables at both lunch and dinner every day and up to 3 pieces of fresh fruit every day. They are also advised to use extra olive oil for cooking and salad dressings, to have nuts every day and to eat 3 portions of semi-skimmed dairy products. They are also told to eat wholegrain cereals and to avoid biscuits, pastries and cakes. They are encouraged to partake of moderate physical activity (for example, to climb four floors of steps four times a day) every day. They are assessed during their usual visits to the Obstetrics department. During their first visit, they are asked to fill in a nutritional questionnaire and give blood samples as well as sit a medical interview. They then receive nutritional recommendations during their second visit and are tested throughout their pregnancy for GDM and to check whether they are following the dietary advice.

What are the possible benefits and risks of participating?
All the participants will gain nutritional education beneficial for the development of their pregnancy. There are no side effects.

Where is the study run from?
Hospital Clínico San Carlos, Madrid (Spain)

When is the study starting and how long is it expected to run for?
February 2016 to June 2020

Who is funding the study?
Investigator initiated and funded

Who is the main contact?
Dr Nuria García de la Torre Lobo

Trial website

Contact information



Primary contact

Dr Nuria García de la Torre Lobo


Contact details

Servicio de Endocrinología y Nutrición.
Hospital Clínico San Carlos. C/Profesor Martín Lagos s/n.

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Efficiency of a dietary intervention based on the Mediterranean diet in the clinical setting in the incidence of gestational diabetes mellitus


Study hypothesis

The efficacy of a nutritional intervention in the clinical setting based on the mediterranean diet is not inferior to the results obtained from a clinical trial (ISRCTN84389045) in the incidence of gestational diabetes mellitus.

Ethics approval

CEIC Hospital Clínico San Carlos, 08/11/2016, ref: 16/442-E

Study design

Unicentric prospective and interventional

Primary study design


Secondary study design

Non randomised study

Trial setting


Trial type


Patient information sheet

See additional files


Gestational Diabetes Mellitus


A nutritional intervention based on the Mediterranean diet will be given to all pregnant women attending the study hospital in the first gestational visit (gestational weeks 8 to 12).

All participants will have the usual follow-up visits in the Obstetrics department, and also in the Endocrinology department in case gestational diabetes is diagnosed.

Visit 0: between 8-12 gestational weeks: Consent signature, medical interview, blood sample, and nutritional questionnaire.
Visit 1: one week later: inclusion criteria compliance, blood sample, and nutritional recommendations.
Visit 2: Between 24-28 gestational weeks; oral glucose tolerance test with 75 g of glucose for identification of gestational diabetes with the IADPSG criteria, nutritional questionnaire and blood and urine sample.
Visits 3-4 (and 4’, if needed): Gestational weeks 28 to 38 if they are diagnosed with gestational diabetes for the usual follow up in the Endocrinology department.
Visit 5: 38 gestational week: nutritional questionnaire, blood and urine sample.
Visit 6: 12 weeks postpartum: clinical evaluation, nutritional questionnaire and blood sample.

The intervention will include these main recommendations:
1. To have fresh vegetables at lunch and dinner daily (any type of vegetables)
2. To have fresh fruit for dessert at lunch and dinner daily ( maximum 3 portions a day, avoid juices)
3. To use extra virgin olive oil daily for cooking and dressings
4. To have nuts daily (as snacks and for salads)
5. To have 3 portions of semi skimmed dairies daily
6. To have wholegrain cereals instead of whites. To avoid biscuits, pastries, and cakes
7. To perform moderate physical activity (to climb four floors of steps four times daily)

Intervention type



Drug names

Primary outcome measure

Incidence of gestational diabetes mellitus at 24-28 gestational weeks. The diagnosis of gestational diabetes mellitus will be established with a 75 g oral glucose tolerance test according to the criteria o IADPSG 2009 and WHO 2013.

Secondary outcome measures

Current secondary outcome measures as of 04/12/2018:
Participants were enrolled at 8-12 gestational weeks (GWs) (visit 0) and were followed-up at GWs 12-14 (visit 1), 24-28 (visit 2), 34-36 (visit 3-4) and delivery (visit 5), as well as at 12 weeks post partum (visit 6):
1. The diagnosis of GDM was established with a 75 g oral glucose tolerance test according to the criteria of IADPSG 2009 and WHO 2013 in visit 2.
2. Pregestational body weight (BW) was self-referred and registered at Visit 1. BW in each visit (1,2, 3 and 4) was measured without shoes and with lightweight clothes. Weight gain was evaluated at 24-28 and 36-38 GW (in relation to BW at Visit 1)
3. Blood pressure was measured with an adequate armlet when the participants had been seated for 10 minutes
4. Need of insulin therapy was registered from endocrinology clinical records after GDM diagnosis at visit 2 (Visits 2, 3 and 4)
5. Pregnancy-induced hypertension (≥140mmHg systolic blood pressure/90 mmHg diastolic blood pressure after 20 GW)
6. Preeclampsia (≥140mmHg systolic/90 mmHg diastolic with proteinuria ≥300 mg in 24-h after 20 GW; albuminuria (proteinuria≥ 300 mg in 24-h with systolic blood pressure <140 mmHg and diastolic blood pressure <90 mmHg)
7. UTIs (number of events requiring antibiotic treatment) recorded at each visit
8. Type of delivery (vaginal, instrumental or caesarean section) and perineal trauma (any degree of spontaneous tears and episiotomy) recorded from obstetric clinical records
9. Gestational age at birth, prematurity (<37 GW), birth weight (g), height (cm) and percentiles, LGA, SGA according to national charts, and NICU admissions were registered from clinical records.

Previous secondary outcome measures:
Percentage of women with a weight gain at the last gestational visit (weeks 37-40)

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Pregnant women older than 18 with fasting glucose levels < 92 mg/dl in the first gestational visit (gestational week 8 to 12).

Participant type


Age group




Target number of participants


Total final enrolment


Participant exclusion criteria

1. Pregnant women with fasting glucose levels >92 mg/dl in the first gestational visit (gestational week 8 to 12)
2. Intolerance/allergy to nuts or olive oil, multiple pregnancy, and any disease or medical treatment that can have an effect on the intervention. Women with specific nutritional treatments

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Hospital Clínico San Carlos
calle Profesor Martín Lagos s/n

Sponsor information


The Health Research Institute of San Carlos (Instituto de Investigación Sanitaria San Carlos)

Sponsor details

San Carlos Hospital. (Hospital Clínico San Carlos)
c/Profesor Martín Lagos s/n

Sponsor type

Research organisation



Funder type


Funder name

Investigator initiated and funded

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

The trialists hope to have results published from phase 1 before the end of 2019. Results from phase 2 will be published in 2021.

IPD sharing plan:
Please request access to participant level data by emailing

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

2019 results in: (added 15/01/2020)

Publication citations

Additional files

Editorial Notes

13/07/2020: Internal review. 15/01/2020: The following changes have been made: 1. Publication reference added. 2. The total final enrolment number has been added from the reference. 04/12/2018: The following changes were made to the trial record: 1. The recruitment end date was changed from 01/11/2017 to 31/12/2019. 2. The overall trial end date was changed from 01/11/2017 to 01/06/2020. 3. The intention to publish date was changed from 31/12/2018 to 31/12/2019. 4. The secondary outcome measures were updated. 5. The target number of participants was changed from 1514 to 873. 30/08/2017: Ethics approval has been added. 23/11/2016: The participant information sheet has been uploaded.