Effect of Low Glycemic Index on Gestational Diabetes Mellitus

The purpose of this study is to determine whether glycemic index is effective in the treatment of maternal glycemia and pregnancy outcomes in women with Gestational Diabetes Mellitus.

1. This research is divided into 2, that are study I and study II

1. Study I, is to determine the long-term effects of intervention (low GI and SNT) on maternal glycemia, pregnancy outcomes and postprandial metabolic markers in women with GDM

   * A total of 110 women with confirmed diagnosis of GDM will be recruited
   * They will be randomized either to receive low GI (n=55) or Standard Nutrition Therapy (SNT; n=55)
   * The intervention will be started as soon as the women being diagnosed with GDM and they will be followed-up every month until delivery and up to the 3-month postpartum.
   * The primary outcome measures include glycemic control parameters as assessed by fasting and postprandial glycemia, fructosamine, HbA1c, insulin level and requirement for insulin treatment.
   * Secondary outcomes include lipid profile, weight gain, measures of postprandial metabolic response (free fatty acid and triglyceride), pregnancy outcomes, and overall improvement in postpartum metabolic parameters.
2. Study II, a sub-Mixed-meal Tolerant Test (MTT) study will be conducted to determine postprandial glycemic and metabolic responses before and after 4-weeks of intensive intervention

   * During the 4-weeks of intensive intervention, the subjects will receive individualise counseling and daily food supply regarding the allocated study group.
   * A minimum of 19 subjects from a pool of 110 subjects who is participated in the intervention study will be recruited.
   * The MTT procedure is similar to the oral glucose tolerant test (OGTT) but the subject will be asked to consume the real mixed meals representing low and high GI foods rather than oral glucose solution.
   * Subject will be asked to consume the test meal (either low or high GI foods) and the blood will be sampled before and after consuming the test meal in two different occasions with 1-week wash-out period.
   * After one month of intensive intervention, 19 subjects from each arm will undergo the final HGI meal tolerant test (MTT3) and the same procedure of MTT 1 and 2
   * Approximately 32μl of capillary blood by finger-prick will be obtained 7 times per MTT session, which is every 30 minutes thereafter to complete 3-h postprandial meal for each set of meal tests.

Eligibility Criteria:
Study I

Inclusion Criteria:

* Pregnant women, aged 18-45 years
* Women diagnosed with Gestational Diabetes Mellitus (GDM) as early as 13 up to 28 weeks of gestation
* Pre-pregnancy BMI \>23kg/m2 (using BMI cut-off point) for underweight and overweight of Asian as defined by World Health Organization (WHO, 2000)
* Treated with diet controlled or on insulin therapy
* Willing and able to comply with the study protocol

Exclusion Criteria:

* Any gastrointestinal disease that interferes with bowel function and nutritional intake (i.e., diabetes-related constipation or diarrhea secondary to neuropathy, diarrhea due to chronic inflammatory bowel disease, gastroparesis, gastrectomy, galactosemia, hyperemesis
* Any medical problem that requires steroid (i.e., arthritis, asthma, autoimmune diseases and skin conditions such as eczema
* Incapability to comply with study protocol or investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements

Study II

Inclusion Criteria:

* Pregnant women, aged 18-45 years
* Only women diagnosed with Gestational Diabetes Mellitus (GDM) between 16 and 28 weeks of gestation
* Pre-pregnancy BMI \>23kg/m2 (using BMI cut-off point) for underweight and overweight of Asian as defined by WHO (2000)
* Treated with diet-controlled alone
* Hemoglobin ≥10mmol/l (WHO, 2011)
* Willing and able to comply with the protocol

Exclusion Criteria:

* Any gastrointestinal disease that interferes with bowel function and nutritional intake (i.e., diabetes-related constipation or diarrhea secondary to neuropathy, diarrhea due to chronic inflammatory bowel disease, gastroparesis, gastrectomy, galactosemia, hyperemesis)
* Currently on insulin therapy
* With known food allergy/ on a particular dietary requirement
* Incapability to comply with study protocol or investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements