A clinical trial will be conducted in Chemical pathology department in collaboration with Gyne &Obs department of PRH, IIMC over a period of 02 years w.e.f. December 15, 2023. 350 pregnant women with 07-11 weeks of gestation and having a high risk for GDM with low Vitamin D3 levels and normal response to 75g OGTT will be randomly assigned to receive either vitamin D3 supplementation (2 00,000 IU/Week) for 04 -06 weeks or Placebo. These women will be checked for the diagnosis of GDM with 75 g OGTT at 24- 28 weeks of gestation. The outcome of the study will be the incidence of GDM based on the International Association of Diabetes and Pregnancy Study Groups Criteria.

Gestational diabetes mellitus is a common condition among pregnant women with metabolic implications for both the mother and offspring. Studies have suggested a potential role of vitamin D status in GDM risk, but evidence from randomized controlled trials is inadequate and inconclusive. A research has been planned to investigate the effect of vitamin D supplementation on GDM development among high risk pregnant women through a well-designed RCT Pregnant women at a risk to develop GDM with low vitamin D levels (<30 ng/mL) at 07-11 weeks of gestation will be recruited and randomly assigned to receive either vitamin D3 supplementation (2 00,000 IU/Week) for 04 -06 weeks or placebo. Randomization will be achieved using a computer-generated random sequence or a randomization table. The allocation will be done in a 1:1 ratio, with equal numbers of participants assigned to the vitamin D and placebo groups. The primary outcome will be the incidence of GDM based on the International Association of Diabetes and Pregnancy Study Groups Criteria after 75 g OGTT.

This study will contribute to the understanding of the relationship between vitamin D and GDM risk through a well-designed RCT with integrated approaches. The findings may inform clinical practice and public health recommendations for vitamin D supplementation during pregnancy.

Inclusion Criteria:

• Pregnant women with 07-11 weeks of gestation
• 21 - 40 Years age range
• Pregnant women with high risk for GDM
• history of GDM in their previous pregnancy,
• one or more first-degree relative diagnosed with diabetes mellitus,
• overweight-BMI >25 kg/m2 or obese-BMI >30 kg/m2 at their first antenatal visit
• with a history of polycystic ovarian syndrome.
• Pregnant women with 07-11 weeks of gestation having normal response to 75g OGTT
• Low levels of Vitamin D3 (<30ng/ml)

Exclusion Criteria:

• Women already diagnosed with diabetes mellitus
• Any other systemic disease.
• High risk pregnant women diagnosed with diabetes on the basis of 75g OGTT
• High risk pregnant women with normal vitamin D3 levels (>30ng/ml).