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.
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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
99
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.
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.
MAIN STUDY ONLY: St Joseph's Heathcare Hamilton, 50 Charlton Avenue East
Hamilton, Ontario, Canada
St. Michael's Hospital
Toronto, Ontario, Canada
Mt Sinai Hospital
Toronto, Ontario, Canada
Sunnybrook Health Sciences Centre
Toronto, Ontario, Canada
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)
Time frame: 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.
Time frame: 1 week and 8 weeks postpartum
MAIN STUDY: Infant birth weight
Weight of the baby at delivery in grams.
Time frame: 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)
Time frame: 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.
Time frame: From randomization to delivery
MAIN STUDY: Insulin prescription incidence
Proportion of women prescribed insulin during the intervention
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 6-8 weeks after delivery
MAIN STUDY: Post-partum fasting serum glucose
Venous fasting serum glucose 6-8 weeks after delivery
Time frame: 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).
Time frame: 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.
Time frame: 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.
Time frame: 6-8 weeks after delivery
MAIN STUDY: Maternal weight gain
Difference between reported pre-pregnancy body weight and last body weight measured before delivery.
Time frame: 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.
Time frame: From randomization to delivery
MAIN STUDY: Change in infant weight
Difference between infant birthweight and weight 6-8 weeks after delivery.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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
Time frame: 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
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 6-8 weeks after delivery
MAIN STUDY: Infant waist circumference at 6-8 weeks
Infant waist circumference at 6-8 weeks.
Time frame: 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.
Time frame: Change from randomization to delivery
MAIN STUDY: Maternal height at baseline
Maternal height at baseline
Time frame: Baseline
MAIN STUDY: Maternal medical history
Maternal medical history
Time frame: 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
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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 frame: 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.
Time frame: change from baseline to 4 weeks.
MAIN STUDY: Conjugated dienes post-partum
Conjugated dienes in fasting venous blood 6-8 weeks after delivery
Time frame: 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
Time frame: 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.
Time frame: 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
Time frame: 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.
Time frame: Change from baseline to 6-8 weeks postpartum
MAIN STUDY: Infant feeding practices
Maternal infant feeding practices from delivery to 6-8 weeks postpartum
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Change in behaviour from baseline (pre-class) to 6-8 weeks after delivery
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