What are the guidelines for diagnosis and management of Gestational Diabetes Mellitus (GDM) in India?

Guidelines for Diagnosis and Management of Gestational Diabetes Mellitus (GDM) in India

The diagnosis and management of Gestational Diabetes Mellitus (GDM) in India follows two main approaches: the one-step and two-step strategies, with the one-step approach being increasingly preferred due to its ability to identify more cases of GDM and potentially reduce adverse pregnancy outcomes.

Diagnostic Approaches for GDM

One-Step Approach

• The one-step approach uses a 75g oral glucose tolerance test (OGTT) with plasma glucose measurements taken when fasting and at 1 and 2 hours, performed between 24-28 weeks of gestation 1, 2
• Diagnosis is made when any of the following plasma glucose values are met or exceeded:
  • Fasting: 92 mg/dL (5.1 mmol/L)
  • 1 hour: 180 mg/dL (10.0 mmol/L)
  • 2 hour: 153 mg/dL (8.5 mmol/L) 1, 3
• This approach identifies approximately 15-20% of pregnant women with GDM, which is 2-3 times more cases than the two-step approach 1, 2

Two-Step Approach

• Step 1: Perform a 50g glucose load test (GLT) without fasting, with plasma glucose measurement at 1 hour, at 24-28 weeks of gestation 1
• If the plasma glucose level at 1 hour is ≥130,135, or 140 mg/dL (7.2,7.5, or 7.8 mmol/L), proceed to a 100g OGTT 1, 3
• Step 2: The 100g OGTT should be performed after fasting 1
• Diagnosis is made when at least two of the following plasma glucose levels are met or exceeded:
  • Fasting: 95 mg/dL (5.3 mmol/L)
  • 1 hour: 180 mg/dL (10.0 mmol/L)
  • 2 hour: 155 mg/dL (8.6 mmol/L)
  • 3 hour: 140 mg/dL (7.8 mmol/L) 1
• The American College of Obstetricians and Gynecologists notes that one elevated value can be used for diagnosis 1

DIPSI Approach (Specific to India)

• The Diabetes in Pregnancy Study Group India (DIPSI) recommends a non-fasting OGTT with 75g of glucose with a cut-off of ≥140 mg/dl after 2 hours 4
• This approach is more practical in the Indian context as it doesn't require women to come fasting 4

Early Screening Recommendations

• Risk assessment for GDM should be undertaken at the first prenatal visit 1, 5
• Women with high-risk characteristics (marked obesity, personal history of GDM, glycosuria, strong family history of diabetes, or high-risk ethnicity) should undergo glucose testing as soon as feasible 1, 5
• If initial screening is negative, high-risk women should be retested between 24-28 weeks of gestation 1, 5
• Women of average risk should have testing undertaken at 24-28 weeks of gestation 1, 3

Management of GDM

Lifestyle Modifications

• Nutritional therapy with calorie restriction and a low glycemic index diet is recommended as first-line treatment to avoid postprandial hyperglycemia and reduce insulin resistance 6
• Regular exercise is recommended as part of lifestyle modifications 6
• Blood glucose levels, HbA1c levels, and ketonuria should be monitored to analyze the efficacy of conservative management 6

Pharmacological Therapy

• Pharmacological treatment is initiated if conservative strategies fail to provide expected glucose levels during follow-ups 6
• Insulin has traditionally been the first choice for treatment of diabetes during pregnancy 6
• Metformin is increasingly being used when insulin cannot be prescribed, although up to 46% of women may require additional insulin to maintain expected blood glucose levels 6

Postpartum Follow-up

• Women with GDM should be screened for persistent diabetes at 4-12 weeks postpartum using a 75g OGTT 1, 3
• Women with a history of GDM should have lifelong screening for diabetes or prediabetes at least every 3 years 1, 3
• Women found to have prediabetes should receive intensive lifestyle interventions or metformin to prevent diabetes 1, 3

Clinical Considerations and Controversies

• The one-step approach identifies more women with GDM but its clinical benefit in reducing adverse pregnancy outcomes remains controversial 7
• Women diagnosed with GDM by the one-step approach have a 3.4-fold higher risk of developing prediabetes and type 2 diabetes later in life 5
• The IADPSG criteria (one-step approach) is the only outcome-based criteria and has the advantage of simplicity in execution, being more patient-friendly, and accurate in diagnosis 4
• Given the diversity and variability of the Indian population, further comparative studies are required on different diagnostic criteria in relation to adverse pregnancy outcomes 4

Delivery Considerations

• Women with diet-controlled GDM can wait for spontaneous labor if there are no obstetric indications for birth 6
• For women with GDM under insulin therapy or with poor glycemic control, elective induction at term is recommended 6