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

Study Overview
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Brief Summary
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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
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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.

Official Title
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The Effect of a Low GI Diet on Maternal and Neonatal Markers of Glycaemic Control and Postpartum Diabetes Risk SUBSTUDY The Effect of a Low GI Diet on Postpartum Markers of Oxidation in Breast Milk of Women With Gestational Hyperglycaemia

Conditions
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Gestational Diabetes Mellitus

Intervention / Treatment
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* Other: Standard Care
* Other: Low GI diet


Participation Criteria
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Eligibility Criteria
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MAIN STUDY Inclusion Criteria: Women: ≥ 18 years of age diagnosed with gestational diabetes mellitus (GDM) or impaired glucose tolerance of pregnancy (IGTP) according to Canadian Diabetes Association (CDA) criteria being followed within DIP (one of 4 sites) willing and able to give informed consent willing and able to comply with the study protocol Exclusion Criteria: Women: 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.). known to have type 1 or type 2 DM prior to pregnancy known multi-fetal pregnancy at enrolment ≥ 33 weeks' gestation prescribed oral anti-hyperglycaemic medication insurmountable language barriers SUB-STUDY control group (women without GDM) Same as for Main study except absence of GDM

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Standard Care<br>Standard care dietary advice to emphasize high fiber foods with a moderate to high GI | Other: Low GI diet<br>* Nutrition education according to standard care similar to the control group with supplementary GI-education. GI-education will be taught using the Stop-Light-Method. This groups will be provided with food substitution lists (key-foods method) composed of low-GI carbohydrate-containing food. The GI-education tool(s) will build on standard care education where patients are taught which food groups contain carbohydrate.<br>* Other names: low glycaemic carbohydrates;|
| Experimental: Low GI Diet<br>Low GI dietary advice in addition to standard care | Other: Standard Care<br>* Standard dietary advice for women with GDM with special emphasis on use of high fiber or whole grain carbohydrate foods with a medium to high GI. What's on Your Plate? and 3-dimensional food models will be used to teach servings size and meal planning. This groups will be provided with food substitution lists (key-foods method) composed of medium to high GI foods.<br>* Other names: medium to high Glycaemic Index;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| MAIN STUDY: Percentage of postprandial self monitored blood glucose (SMBG) values within the target range | 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) | From randomization to delivery | 
| SUB-STUDY (n=75): Oxygen Radical Absorbance Capacity (ORAC) (Antioxidant Capacity) of transitional and mature breast milk. | 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. | 1 week and 8 weeks postpartum | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| MAIN STUDY: Infant birth weight | Weight of the baby at delivery in grams. | At delivery | 
| MAIN STUDY: Percentage of self-monitored fasting glucose values within the target range | 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) | From randomization to delivery | 
| MAIN STUDY: Glucose variability | 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. | From randomization to delivery | 
| MAIN STUDY: Insulin prescription incidence | Proportion of women prescribed insulin during the intervention | From randomization to delivery | 
| MAIN STUDY: Mean fasting glucose | 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. | From randomization to delivery | 
| MAIN STUDY: Mean postprandial glucose | 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. | From randomization to delivery | 
| MAIN STUDY: Mean post-breakfast glucose | 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. | From randomization to delivery | 
| MAIN STUDY: Mean post-lunch blood glucose | 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. | From randomization to delivery | 
| MAIN STUDY: Mean post-dinner blood glucose | 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. | From randomization to delivery | 
| MAIN STUDY: Change in LDL oxidation at 4 weeks | Difference between LDL oxidation measured in fasting venous blood at randomization and 4 weeks. | Change from randomization in LDL oxidation at 4 weeks. | 
| MAIN STUDY: LDL oxidation 6-8 weeks after delivery | LDL oxidation measured in fasting venous blood 6-8 weeks after delivery. | 6-8 weeks after delivery | 
| MAIN STUDY: Change in Oxygen Radical Absorbance Capacity (ORAC) of plasma at 4 weeks | Difference in Oxygen Radical Absorbance Capacity (ORAC) of plasma measured in venous serum at randomization and 4 weeks. | Change from randomization to 4 weeks | 
| MAIN STUDY: Change in c-reactive protein (CRP) at 4 weeks | Difference in c-reactive protein concentration in venous serum from baseline at 4 weeks. | Change in CRP from randomization at 4 weeks | 
| MAIN STUDY: Post-partum CRP | Concentration of venous serum c-reactive protein 6-8 weeks after delivery. | 6-8 weeks after delivery | 
| MAIN STUDY: Post-partum fasting serum glucose | Venous fasting serum glucose 6-8 weeks after delivery | 6-8 weeks after delivery | 
| MAIN STUDY: Post-partum serum glucose concentration 2 hours after consumption of 75g oral glucose (2hrPC serum glucose). | Venous serum glucose concentration 2 hours after consumption of 75g oral glucose (oral glucose tolerance test). | 6-8 weeks after delivery | 
| MAIN STUDY: Incidence of post-partum impaired glucose tolerance | 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. | 6-8 weeks after delivery | 
| MAIN STUDY: Incidence of post-partum diabetes mellitus | 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. | 6-8 weeks after delivery | 
| MAIN STUDY: Maternal weight gain | Difference between reported pre-pregnancy body weight and last body weight measured before delivery. | From pre-pregnancy to delivery: up to 9 months | 
| MAIN STUDY: Rate of maternal weight gain | Difference between maternal body weight at randomization and last body weight measured before delivery divided by the number of weeks between the measurements. | From randomization to delivery | 
| MAIN STUDY: Change in infant weight | Difference between infant birthweight and weight 6-8 weeks after delivery. | Change in infant body weight from birth to 6- 8 weeks | 
| MAIN STUDY & SUB-STUDY (n=75): Maternal dietary intake | 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. | From randomization to 6- 8 weeks post-partum | 
| SUB-STUDY (n=75): Concentration of vitamin C, E, and Beta-carotene in transitional breast milk | 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. | 1 week after delivery | 
| SUB-STUDY (n=75): Concentration of vitamin C, E, and Beta-carotene in mature breast milk | 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. | 6-8 weeks after delivery | 
| MAIN STUDY: Infant demographics | 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 | Delivery to 6-8 weeks postpartum | 
| MAIN STUDY: Change in infant body measurements from birth to 6-8 weeks post-partum | Weight, head circumference, and height/length | Change in infant body measurements from delivery to 6-8 weeks post-partum | 
| MAIN STUDY: Infant APGAR score at delivery | Infant APGAR score at delivery as recorded in maternal medical chart. | Delivery | 
| MAIN STUDY: Change in maternal blood pressure and resting pulse from randomization to 4 weeks | Difference between maternal blood pressure and resting pulse from randomization at4 weeks. | Change from randomization to 4 weeks. | 
| MAIN STUDY: Maternal blood pressure and resting pulse at 6-8 weeks post-partum | Maternal blood pressure and resting pulse at 6-8 weeks post-partum. | 6-8 weeks after delivery | 
| MAIN STUDY: Infant waist circumference at 6-8 weeks | Infant waist circumference at 6-8 weeks. | 6-8 weeks after delivery | 
| MAIN STUDY: Change in ultrasound measurements from randomization to delivery. | Difference between infant ultrasound measurements (Bi-parietal diameter, head circumference, abdominal circumference, and femur length) from baseline to delivery. | Change from randomization to delivery | 
| MAIN STUDY: Maternal height at baseline | Maternal height at baseline | Baseline | 
| MAIN STUDY: Maternal medical history | Maternal medical history | Baseline | 
| MAIN STUDY: Maternal medical complications from baseline to 6-8 weeks post-partum | Incidence and type of maternal medical complications from baseline to 6-8 weeks post-partum | Baseline to 6-8 weeks after delivery | 
| MAIN STUDY: Change in maternal weight from delivery at 6-8 weeks post-partum | Difference in maternal weight from delivery at 6-8 weeks postpartum. | Difference between delivery and 6-8 weeks post-partum | 
| MAIN STUDY: Maternal pre-natal demographic information | 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. | Baseline | 
| MAIN STUDY: Maternal post-partum socio-demographic data related to infant feeding practices | Socio-demographic factors previously identified in the literature as affecting infant feeding practices; including access to breastfeeding education while in hospital. | 6-8 weeks after delivery | 
| MAIN STUDY: Length of time between delivery and maternal breast fullness | Length of time between delivery and maternal breast fullness. | Time after delivery | 
| MAIN STUDY: Change in conjugated dienes at 4 weeks | Difference between conjugated dienes of plasma measured in venous serum at baseline and 4 weeks. | change from baseline to 4 weeks. | 
| MAIN STUDY: Conjugated dienes post-partum | Conjugated dienes in fasting venous blood 6-8 weeks after delivery | 6-8 weeks after delivery | 
| MAIN STUDY: Oxygen Radical Absorbance Capacity (ORAC) of venous plasma post-partum | ORAC measured in fasting venous blood 6-8 weeks after delivery | 6-8 weeks after delivery | 
| MAIN STUDY: Change in full lipid profile at 4 weeks | Difference in full lipid profile of fasting venous blood at baseline and 4 weeks. | Change in full lipid profile of plasma from baseline at 4 weeks | 
| MAIN STUDY: Full lipid profile post-partum | Full lipid profile of fasting venous blood at 6-8 weeks post-partum | 6-8 weeks after delivery | 
| MAIN STUDY: Change in incidence and severity of symptoms 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. | Change from baseline to 6-8 weeks postpartum | 
| MAIN STUDY: Infant feeding practices | Maternal infant feeding practices from delivery to 6-8 weeks postpartum | 6-8 weeks after delivery | 
| MAIN STUDY: Participant satisfaction of baseline education class | Participant reactions and opinions on baseline education class using a face-validated, pre-tested questionnaire. | Baseline | 
| MAIN STUDY: Change in participant knowledge of GI from baseline 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. | Change in GI knowledge from randomization to 6-8 weeks after delivery | 
| MAIN STUDY: Participant knowledge of GI at baseline | Participant knowledge of GI at baseline (pre-education class)using a validated questionnaire. | Baseline | 
| MAIN STUDY: Change in participant opinion on availability and acceptability of study diet foods | 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. | Change in opinion from 2 weeks to 6-8 weeks after delivery | 
| MAIN STUDY: Difference in dietary GI between study groups. | 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. | From baseline to 6-8 weeks after delivery | 
| MAIN STUDY: 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. | Change in behaviour from baseline (pre-class) to 6-8 weeks after delivery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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glycaemic index, glycemic index, hyperglycemia, pregnancy, hyperglycaemia, dietary intervention, education evaluation, antioxidant, Impaired Glucose Tolerance of Pregnancy, Gestational Diabetes Mellitus, Breast Milk