MAIN STUDY: Low Glycaemic Index (GI) Diet in the Management of GDM SUB-STUDY: The Breast Milk Sub-Study

Phase 2

Completed

• Conditions: Gestational Diabetes Mellitus
• Interventions: Other: Low GI diet; Other: Standard Care

• Registration Number: NCT01589757
• Lead Sponsor: University of Toronto

Brief Summary

MAIN STUDY: Low glycaemic index (GI) diets are recommended by the Canadian Diabetes Association for treating type 1 and 2 diabetes mellitus (DM), but the role of GI in the management of gestational diabetes(GDM)is not yet clear. The main purpose of this study is to determine the effect of a low GI diet on blood sugar control in women with GDM. The effect of a low GI diet on maternal oxidative stress, pregnancy and delivery outcomes and markers of risk for diabetes after birth in both the mother and baby will also be assessed. SUB-STUDY: The main purpose of the sub-study is to determine if the breast milk (BM) of women with GDM consuming a low GI diet will have a higher antioxidant capacity than the BM of women receiving a medium-high GI diet (control/standard care). The effect of a low glycaemic index diet on maternal dietary intake of specific nutrient-antioxidants (i.e. vitamin C, E, and beta-carotene) (prenatal and postpartum) and concentration of vitamin C, E, and beta-carotene in participants' transitional and mature BM will also be assessed. The ORAC (Oxygen radical absorbance capacity) assay will be used to assess overall antioxidant capacity. The antioxidant capacity of BM in women with GDM will also be compared with that of women without GDM.

Hypotheses:

MAIN: The use of low-GI foods in the management of GDM reduces postprandial BG and oxidative stress; thereby reducing maternal and infant perinatal complications.

SUB-STUDY: Breast milk (BM) of women with GDM consuming a low GI diet will have higher BM antioxidant than women receiving the medium to high GI diet. BM of women with GDM will have lower antioxidant capacity than that of women without GDM.

Detailed Description

MAIN STUDY: Use of low GI education is currently accepted by the Canadian Diabetes Association in treatment of type 1 and 2 DM, but is not included in the clinical practice guidelines(CPG) for management of GDM. Data collected to date support use of low GI in treatment of GDM, but more data are needed to influence CPG. In this study the effect of a low GI diet on maternal and neonatal markers of glycaemic control and postpartum diabetes risk in mother and baby will be determined. This study will also assess the role that maternal oxidative stress may play in this relationship.

Hypothesis: The use of low-GI foods in the management of GDM reduces postprandial BG and oxidative stress; thereby reducing maternal and infant perinatal complications.

SUB-STUDY: Breast milk (BM) is accepted as the optimal source of nutrition for infants. A wealth of literature on BM composition exists. This work includes measurement of antioxidants in BM. Women diagnosed with gestational hyperglycaemia have decreased antioxidant capacity in comparison to normoglycaemic pregnant women. A direct relationship exists between postprandial glycaemic response and oxidative stress. Low GI carbohydrate is converted to blood glucose (BG) more slowly than medium to high GI carbohydrate

Hypotheses: Breast milk (BM) of women with GDM consuming a low GI diet will have higher BM antioxidant than women receiving the medium to high GI diet. BM of women with GDM will have lower anti-oxidant capacity than that of women without GDM.

Study Timeline

• Study Start: 2011-10
• Study First Submitted: 2012-04-19
• Study First Submitted QC: 2012-05-01
• Study First Posted: 2012-05-02
• Primary Completion: 2015-09
• Study Completion: 2015-09
• Status Verified: 2016-05
• Last Update Submitted: 2016-05-19
• Last Update Posted: 2016-05-20

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 99

Inclusion Criteria

Women:

1. ≥ 18 years of age
2. diagnosed with gestational diabetes mellitus (GDM) or impaired glucose tolerance of pregnancy (IGTP) according to Canadian Diabetes Association (CDA) criteria
3. being followed within DIP (one of 4 sites)
4. willing and able to give informed consent
5. willing and able to comply with the study protocol

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Exclusion Criteria

Women:

1. with acute or chronic illness other than GDM or IGTP or use of drug (other than insulin) which may affect carbohydrate metabolism, gastrointestinal function or carbohydrate digestion (i.e. crohn's disease, HIV/AIDS, liver disease, kidney disease etc.).
2. known to have type 1 or type 2 DM prior to pregnancy
3. known multi-fetal pregnancy at enrolment
4. ≥ 33 weeks' gestation
5. prescribed oral anti-hyperglycaemic medication
6. insurmountable language barriers

SUB-STUDY control group (women without GDM) Same as for Main study except absence of GDM

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Standard Care	Low GI diet	Standard care dietary advice to emphasize high fiber foods with a moderate to high GI
Low GI Diet	Standard Care	Low GI dietary advice in addition to standard care

Primary Outcome Measures

Name	Time	Method
MAIN STUDY: Percentage of postprandial self monitored blood glucose (SMBG) values within the target range	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. The endpoint is a single value for each participant - namely the percentage of all the postprandial SMBG values within the target range recommended by the Canadian Diabetes Association (5.0 to 6.6 mmol/L)
SUB-STUDY (n=75): Oxygen Radical Absorbance Capacity (ORAC) (Antioxidant Capacity) of transitional and mature breast milk.	1 week and 8 weeks postpartum	Breast milk samples (25 mL) will be collected 1 week and 8 weeks after birth from a complete breast milk collection. Measures will be compared between and within groups.

Secondary Outcome Measures

Name	Time	Method
MAIN STUDY: Maternal medical history	Baseline	Maternal medical history
MAIN STUDY: Mean postprandial glucose	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. This endpoint is the mean of all postprandial SMBG values obtained; a single value for each participant.
MAIN STUDY: Post-partum serum glucose concentration 2 hours after consumption of 75g oral glucose (2hrPC serum glucose).	6-8 weeks after delivery	Venous serum glucose concentration 2 hours after consumption of 75g oral glucose (oral glucose tolerance test).
MAIN STUDY: Insulin prescription incidence	From randomization to delivery	Proportion of women prescribed insulin during the intervention
MAIN STUDY: Mean post-breakfast glucose	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. This endpoint is the mean of all SMBG values 2 hours after breakfast; a single value in each participant.
MAIN STUDY: Length of time between delivery and maternal breast fullness	Time after delivery	Length of time between delivery and maternal breast fullness.
MAIN STUDY: Change in LDL oxidation at 4 weeks	Change from randomization in LDL oxidation at 4 weeks.	Difference between LDL oxidation measured in fasting venous blood at randomization and 4 weeks.
MAIN STUDY: Change in Oxygen Radical Absorbance Capacity (ORAC) of plasma at 4 weeks	Change from randomization to 4 weeks	Difference in Oxygen Radical Absorbance Capacity (ORAC) of plasma measured in venous serum at randomization and 4 weeks.
MAIN STUDY: Incidence of post-partum impaired glucose tolerance	6-8 weeks after delivery	Proportion of women with venous serum glucose concentration 2 hours after a 75g oral glucose tolerance test between 7.8 and 11.0 mmol/L, inclusive.
MAIN STUDY: Maternal weight gain	From pre-pregnancy to delivery: up to 9 months	Difference between reported pre-pregnancy body weight and last body weight measured before delivery.
MAIN STUDY: Rate of maternal weight gain	From randomization to delivery	Difference between maternal body weight at randomization and last body weight measured before delivery divided by the number of weeks between the measurements.
MAIN STUDY & SUB-STUDY (n=75): Maternal dietary intake	From randomization to 6- 8 weeks post-partum	Dietary analysis will be conducted using software containing the Canadian Nutrient File, supplemented with data that used standardized GI testing methodology. Comparison will be made between and within groups.
MAIN STUDY: Change in maternal blood pressure and resting pulse from randomization to 4 weeks	Change from randomization to 4 weeks.	Difference between maternal blood pressure and resting pulse from randomization at4 weeks.
MAIN STUDY: Change in full lipid profile at 4 weeks	Change in full lipid profile of plasma from baseline at 4 weeks	Difference in full lipid profile of fasting venous blood at baseline and 4 weeks.
MAIN STUDY: Change in participant knowledge of GI from baseline to 6-8 weeks after delivery	Change in GI knowledge from randomization to 6-8 weeks after delivery	Difference in participant knowledge of GI from randomization pre-education class) to 6-8 weeks after delivery using a face-validated, pre-tested questionnaire.
MAIN STUDY: Percentage of self-monitored fasting glucose values within the target range	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the start of the intervention to delivery. The endpoint is a single value for each participant - namely the percentage of all the fasting SMBG values within the target range recommended by the Canadian Diabetes Association (3.8 to 5.2 mmol/L)
MAIN STUDY: Glucose variability	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. This endpoint is the coefficient of variation of all the SMBG values obtained (CV = 100\*SD/mean), where SD is standard deviation; a single value for each participant.
MAIN STUDY: Mean fasting glucose	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. The endpoint is the mean of all fasting SMBG values obtained - a single value for each participant.
MAIN STUDY: Change in c-reactive protein (CRP) at 4 weeks	Change in CRP from randomization at 4 weeks	Difference in c-reactive protein concentration in venous serum from baseline at 4 weeks.
SUB-STUDY (n=75): Concentration of vitamin C, E, and Beta-carotene in mature breast milk	6-8 weeks after delivery	Concentration of vitamin C, vitamin E and beta-carotene in breast milk collected 6-8 weeks after delivery. Comparison will be made between and within study groups.
MAIN STUDY: Change in infant body measurements from birth to 6-8 weeks post-partum	Change in infant body measurements from delivery to 6-8 weeks post-partum	Weight, head circumference, and height/length
MAIN STUDY: Infant APGAR score at delivery	Delivery	Infant APGAR score at delivery as recorded in maternal medical chart.
MAIN STUDY: Maternal pre-natal demographic information	Baseline	Maternal pre-natal demographic information (e.g. ethnicity, language used at home, household food preparation and purchasing, education obtained, employment status, treatment of diabetes, prior exposure to a registered dietitian, cigarette, recreational drug, and alcohol use before and during pregnancy, and physical activity) using a pre-tested, face-validated questionnaire.
MAIN STUDY: Conjugated dienes post-partum	6-8 weeks after delivery	Conjugated dienes in fasting venous blood 6-8 weeks after delivery
MAIN STUDY: Oxygen Radical Absorbance Capacity (ORAC) of venous plasma post-partum	6-8 weeks after delivery	ORAC measured in fasting venous blood 6-8 weeks after delivery
MAIN STUDY: Infant birth weight	At delivery	Weight of the baby at delivery in grams.
MAIN STUDY: Mean post-lunch blood glucose	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. This endpoint is the mean of all SMBG values 2 hours after lunch; a single value in each participant.
MAIN STUDY: Mean post-dinner blood glucose	From randomization to delivery	SMBG values are obtained 4 times daily (1 fasting and 3 postprandial) throughout the study from the randomization to delivery. This endpoint is the mean of all SMBG values 2 hours after dinner; a single value in each participant.
MAIN STUDY: LDL oxidation 6-8 weeks after delivery	6-8 weeks after delivery	LDL oxidation measured in fasting venous blood 6-8 weeks after delivery.
MAIN STUDY: Post-partum CRP	6-8 weeks after delivery	Concentration of venous serum c-reactive protein 6-8 weeks after delivery.
MAIN STUDY: Change in infant weight	Change in infant body weight from birth to 6- 8 weeks	Difference between infant birthweight and weight 6-8 weeks after delivery.
MAIN STUDY: Change in ultrasound measurements from randomization to delivery.	Change from randomization to delivery	Difference between infant ultrasound measurements (Bi-parietal diameter, head circumference, abdominal circumference, and femur length) from baseline to delivery.
MAIN STUDY: Maternal height at baseline	Baseline	Maternal height at baseline
MAIN STUDY: Change in maternal weight from delivery at 6-8 weeks post-partum	Difference between delivery and 6-8 weeks post-partum	Difference in maternal weight from delivery at 6-8 weeks postpartum.
MAIN STUDY: Full lipid profile post-partum	6-8 weeks after delivery	Full lipid profile of fasting venous blood at 6-8 weeks post-partum
MAIN STUDY: Participant satisfaction of baseline education class	Baseline	Participant reactions and opinions on baseline education class using a face-validated, pre-tested questionnaire.
MAIN STUDY: Participant knowledge of GI at baseline	Baseline	Participant knowledge of GI at baseline (pre-education class)using a validated questionnaire.
MAIN STUDY: Post-partum fasting serum glucose	6-8 weeks after delivery	Venous fasting serum glucose 6-8 weeks after delivery
MAIN STUDY: Incidence of post-partum diabetes mellitus	6-8 weeks after delivery	Proportion of women with diabetes 6-8 weeks after delivery. Diabetes is defined as fasting serum glucose greater than or equal to 7.0 mmol/L and/or serum glucose 2 hours after 75g oral glucose tolerance test greater than or equal to 11.1mmol/L.
SUB-STUDY (n=75): Concentration of vitamin C, E, and Beta-carotene in transitional breast milk	1 week after delivery	Concentration of vitamin C, vitamin E and beta-carotene in breast milk collected 1 week after delivery. Comparison will be made between and within study groups.
MAIN STUDY: Maternal blood pressure and resting pulse at 6-8 weeks post-partum	6-8 weeks after delivery	Maternal blood pressure and resting pulse at 6-8 weeks post-partum.
MAIN STUDY: Infant waist circumference at 6-8 weeks	6-8 weeks after delivery	Infant waist circumference at 6-8 weeks.
MAIN STUDY: Maternal medical complications from baseline to 6-8 weeks post-partum	Baseline to 6-8 weeks after delivery	Incidence and type of maternal medical complications from baseline to 6-8 weeks post-partum
MAIN STUDY: Infant feeding practices	6-8 weeks after delivery	Maternal infant feeding practices from delivery to 6-8 weeks postpartum
MAIN STUDY: Infant demographics	Delivery to 6-8 weeks postpartum	Collection of infant demographics, such as gestational age at birth, sex, incidence and type of complications as noted in maternal or infant chart, mode of delivery, length of stay in hospital
MAIN STUDY: Maternal post-partum socio-demographic data related to infant feeding practices	6-8 weeks after delivery	Socio-demographic factors previously identified in the literature as affecting infant feeding practices; including access to breastfeeding education while in hospital.
MAIN STUDY: Change in conjugated dienes at 4 weeks	change from baseline to 4 weeks.	Difference between conjugated dienes of plasma measured in venous serum at baseline and 4 weeks.
MAIN STUDY: Change in participant opinion on availability and acceptability of study diet foods	Change in opinion from 2 weeks to 6-8 weeks after delivery	Difference in participant opinion on availability and acceptability of study diet foods from 2 weeks to 6-8 weeks after delivery using a validated questionnaire.
MAIN STUDY: Change in incidence and severity of symptoms from baseline to 6-8 weeks postpartum	Change from baseline to 6-8 weeks postpartum	Difference in the incidence and severity of maternal symptoms present from baseline to 6-8 weeks postpartum using a standardised questionnaire.
MAIN STUDY: Difference in dietary GI between study groups.	From baseline to 6-8 weeks after delivery	Difference in dietary GI between study groups from baseline to 6-8 weeks post delivery using a short-form semi-quantitative food frequency questionnaire (FFQ). The FFQ collects dietary intake data on the 3 months preceding administration. The FFQ has been standardised and evaluated for readability by nutrition professionals, clinicians and/or researchers with experience in surveying, and has been face-validated and pre-tested.
MAIN STUDY: Change in behaviour from baseline (pre-class) to 6-8 weeks after delivery.	Change in behaviour from baseline (pre-class) to 6-8 weeks after delivery	Difference in behaviour within and between groups from baseline (pre-class) to 6-8 weeks after delivery using face-validated, pre-tested questionnaires, including a short-form semi-quantitative food frequency questionnaire (FFQ). The FFQ collects dietary intake data on the 3 months preceding administration. The FFQ has been standardised and evaluated for readability by nutrition professionals, clinicians and/or researchers with experience in surveying.

Trial Locations

Locations (4)

MAIN STUDY ONLY: St Joseph's Heathcare Hamilton, 50 Charlton Avenue East; 🇨🇦 Hamilton, Ontario, Canada

Mt Sinai Hospital; 🇨🇦 Toronto, Ontario, Canada

St. Michael's Hospital; 🇨🇦 Toronto, Ontario, Canada

Sunnybrook Health Sciences Centre; 🇨🇦 Toronto, Ontario, Canada