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DIABETES IN PREGNANCY - COMPLETE NOTES

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PART 2

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1. Gestational Diabetes Mellitus (GDM)

What is it?

Features

• Complications are similar to pre-gestational DM (pre-GDM), EXCEPT:
  • No congenital anomalies (GCA) - because GDM develops after the first trimester (organogenesis is already complete)
  • No fetal ECHO - as structural heart defects are only a risk in pre-GDM (early hyperglycemia during cardiac development)
• Follow-up and investigations: Same as pre-GDM, with the two exceptions above

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2. Diagnosis - DIPSI Criteria

Recommendations

Procedure

• No fasting required (universal screening regardless of meals)
• Give 75 gm glucose in 300 mL water (lime can be added for taste)
• Patient consumes it in 5-10 minutes
• Check 2-hour postprandial (PP) levels using a plasma-calibrated glucometer

If Patient Vomits:

• Within 30 minutes of drinking glucose - repeat test on another day
• After 30 minutes - continue the test (enough absorption has occurred)

2-Hour PP Interpretation

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3. Management of GDM

Based on 2hr PP Values:

         2hr PP Value
              |
   ┌──────────┴──────────┐
140-199 mg/dL         ≥ 200 mg/dL
   (Initial MNT)      (Immediate Insulin)
       |                     |
  MNT x 2 weeks          8U Insulin
       |                   + MNT
  [Check Metabolic        + Weight counselling
    Goals]               (No role of aspirin)

Metabolic Goals (targets to achieve)

• FBS < 95 mg/dL
• 1hr PP < 140 mg/dL
• 2hr PP < 120 mg/dL
• HbA1c < 6%
• Average capillary glucose < 100 mg/dL

If Goals MET:

• Continue MNT
• Advise 30 min walk daily
• Check 2hr PP levels: 2nd trimester = every 2 weeks, 3rd trimester = weekly, minimum = monthly

If Goals NOT MET:

• Start Metformin → then Insulin + MNT

GOI (Government of India) Treatment Guidelines:

• Diagnosed > 20 weeks → Metformin
• Diagnosed < 20 weeks → Insulin
• 2hr PP > 200 mg/dL (at any time) → Insulin

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4. Medical Nutrition Therapy (MNT)

Diet Composition

• Distributed over 3 meals + 3 snacks

Caloric Requirements

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5. Oral Hypoglycemic Agents (OHAs)

Metformin

• Recommended by GOI (Government of India)
• Used only in GDM (NOT in pre-GDM)
• Only used > 20 weeks of pregnancy
• 1st line drug
• Advantages:
  • Reduces excessive maternal weight gain
  • Reduces neonatal hypoglycemia risk
  • Reduces chances of Large for Gestational Age (LGA) fetus
  • Reduces macrosomia risk
• Preferred in obese patients
• Dose: 500 mg/day → up to 2 g/day
  • If dose needed > 2 g/day → Add Insulin
• Side effects:
  • Most common (m/c): GI side effects
  • Most dangerous: Lactic acidosis

Glyburide

• Dose: 2.5 mg/day → up to 20 mg/day
• Side effect: Increased risk of neonatal hypoglycemia

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6. Insulin in Pregnancy

Type Used

• Human pre-mix insulin 30:70
  • 30% short-acting + 70% intermediate insulin
• 1 vial = 40 IU
• Storage: 4-8°C
• Syringe reused up to 14 times

Insulin Requirement Trends

• Increases with advancing pregnancy (due to rising insulin resistance)
• Decreases during labor (patient is NPO - nothing by mouth)

Starting Insulin

• Start Human Insulin premix 30:70
• Subcutaneous injection, 30 mins before breakfast, once daily (OD)
• Dose calculated by 2hr PP levels:

Dose Titration Flowchart

• Check levels on Day 3
• If goals NOT met:
  • FBS > 95 → Add 2U insulin pre-dinner
  • 2hr PP > 120 → Add 2U before breakfast
• Recheck every 3 days
• Titrate until metabolic goals are met
• Once met: Check every 2 weeks (2nd trimester), weekly (3rd trimester)

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7. Termination of Pregnancy

• Mode of delivery: Vaginal (preferred)
• C-Section indication: Estimated fetal weight ≥ 4.5 kg

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8. Intrapartum (During Labor) Management

• Mild GDM on medical management: Skip the morning insulin dose
• Monitor blood sugar every 2 hours with glucometer
• During labor: NPO + IV Normal Saline (NS) @ 100 mL/hr

Insulin in NS Drip (500 mL NS):

• If blood glucose < 70 mg/dL (hypoglycemia) → Start IV 5% Dextrose

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9. Postpartum Management

GDM:

• Check blood sugar on Day 3 post-delivery
• At discharge → Follow up at 6 weeks with 75g 2hr OGTT
  • Normal → Confirm resolution of GDM → Advise annual 75g OGTT (due to increased risk of developing Type 2 DM)
  • Abnormal → Refer to Endocrinologist

Pre-GDM:

• Insulin requirement decreases from Day 2 of delivery
• Shifted back to OHA
• Refer to endocrinologist if needed

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PART 3 - COMPLICATIONS & SPECIAL TOPICS

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10. Maternal Complications

1. Hyperglycemia - primary problem
2. Infections (increased risk due to high glucose):
   • Asymptomatic bacteriuria
   • Candidiasis
   • Puerperal sepsis
3. Polyhydramnios (excess amniotic fluid) → can cause:
   • Preterm labor (PTL)
   • Premature rupture of membranes (PROM)
   • Cord prolapse
   • PPH (postpartum hemorrhage)
   • Subinvolution
4. Oligohydramnios - due to diabetic vasculopathy or PIH
5. Placentomegaly (Big placenta) - swelling of chorionic villi due to hyperglycemia → raises risk of PIH & placenta previa
6. Future risks: T2DM, C-section, ketoacidosis

Retinopathy Note

• Pre-gestational diabetes with retinopathy → worsens during pregnancy
• All pre-GDM females must have a baseline fundus examination

Hypoglycemia (Blood sugar < 70 mg/dL)

• 3 teaspoons glucose in 100 mL water, OR
• 6 teaspoons sugar in 100 mL water

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11. Fetal Complications - Pedersen's Hypothesis

Maternal Hyperglycemia
        ↓
Fetal Hyperglycemia
        ↓
Stimulates Fetal Pancreas
        ↓
Hyperinsulinemia
    ↙          ↘
↑ Growth    ↓ Lipolysis → Fat deposition around fetal shoulder
    ↓                 ↓
Macrosomia        ↓
         ↘       ↙
        Shoulder Dystocia

Key Fetal Risks:

• Macrosomia → Prolonged labour → Increased C-section rate
• IUGR - only if diabetic vasculopathy or PIH is present
• Increased risk of abortion - in uncontrolled diabetes
• Stillbirth due to:
  • Macrosomia → increased O2 demand → hypoxia
  • Hyperglycemia → oxidative stress → hypoxia
  • Edema of chorionic villi → decreased O2 transport → hypoxia
  • (Most common in last 2 weeks of pregnancy)
• Congenital malformations - ONLY in pre-GDM (not GDM), because organogenesis has already occurred by the time GDM develops
• Hormone for fetal growth: Insulin and IGFs

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12. Neonatal Complications

1. Neonatal Hypoglycemia (Most Important)

• Mechanism: Maternal hyperglycemia → fetal hyperglycemia → fetal hyperinsulinism
• At birth: glucose supply from mother is cut off, but insulin remains high → Hypoglycemia

2-9: Other Neonatal Complications

Important: Anemia is NOT a complication of diabetic pregnancy.

Late Complications in the Child:

• T2DM: 1-3% risk
• Obesity
• Metabolic syndrome (Syndrome X)

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13. Lung Maturity Tests

Nile Blue Sulphate Test (Principle)

• AF fetal skin cells mature at the same time as lungs
• Orange cells = Mature skin cells (stained with dye)
• Blue cells = Immature skin cells

• 50% orange cells = Lungs mature

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14. Shoulder Dystocia

Management - Mnemonic: HELPERR

Other Notes:

• Dead baby: Cleidotomy (fracture clavicle of baby)
• Symphysiotomy: Dividing pubic symphysis of mother - now Obsolete
• CONTRAINDICATED: Fundal pressure (worsens impaction)
• Each manoeuvre performed for a maximum of 30 seconds before moving to the next

Complications of Shoulder Dystocia:

• Erb's Palsy (C5, C6 injury) - most common - arm is internally rotated, adducted, and pronated ("waiter's tip" position)
• Injury to C5, C6 nerve roots

• Injury from manoeuvres

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Summary Table - Quick Recall

Medical Nutrition Therapy (MNT) in Gestational Diabetes

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What is MNT?

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Diet Composition

Notice: Carbohydrates are reduced (normally 55-60% in a regular diet) and fat is kept relatively high - this is intentional to blunt postprandial glucose spikes.

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Meal Distribution

• 3 main meals + 3 snacks throughout the day
• This is important because:
  • Spreading carbs over 6 smaller portions prevents large glucose spikes
  • Prevents prolonged fasting (which can cause ketosis/ketoacidemia, harmful in pregnancy)
  • Keeps insulin demand steady rather than in large surges

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Caloric Requirements

The reason overweight women subtract calories is to limit excessive gestational weight gain, which worsens insulin resistance and increases macrosomia risk - but never starve a pregnant diabetic woman as ketones cross the placenta and harm the fetus.

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What is the Duration of MNT Trial?

• MNT is given a trial of 2 weeks
• After 2 weeks, check if metabolic goals are met:

• Goals met → Continue MNT + 30 min daily walk
• Goals not met → Add Metformin (or Insulin if indicated)

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Additional Lifestyle Advice with MNT

• 30 minutes of moderate walking daily is advised alongside diet
• This improves insulin sensitivity
• Combined with MNT, many GDM patients can be managed without medications

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Why Carbs are 40% (Not Lower)?

• Very low carb diets in pregnancy risk ketoacidosis even at normal blood sugars (starvation ketosis)
• Fetal brain runs on glucose - complete carb restriction is dangerous
• 40% is the "sweet spot" - low enough to reduce glucose load, safe enough to prevent ketosis

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Key Takeaway

MNT is not just a "diet" - it is a structured, calculated therapeutic intervention. It is always the first step in GDM management and continues even after medications are started. It is NEVER stopped.

GDM Management Based on 2hr PP Value - Full Explanation

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The Two Pathways

              2hr PP Value (DIPSI Test)
                        |
         ┌──────────────┴──────────────┐
         │                             │
   140–199 mg/dL                  ≥ 200 mg/dL
   (Mild GDM)                    (Severe GDM)
         │                             │
    START MNT                  IMMEDIATE Insulin
    for 2 weeks                  (8 Units) + MNT
         │                      + Weight Counselling
   Check Metabolic              (No role of Aspirin)
      Goals...

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PATH 1 - 140 to 199 mg/dL

Why MNT first?

• Blood sugar is elevated but not severely so
• Diet control alone has a good chance of bringing it to target
• Avoids unnecessary medication in pregnancy

What happens after 2 weeks of MNT?

         After 2 weeks of MNT
                  |
     ┌────────────┴────────────┐
     │                         │
Goals MET                 Goals NOT MET
     │                         │
Continue MNT            Step 1: Add Metformin
+ 30 min walk daily     (500mg → up to 2g/day)
+ Monitor 2hr PP                │
                        If still not controlled
                                │
                        Step 2: Add Insulin
                                │
                          Continue MNT
                        throughout all steps

Metabolic Goals to check:

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PATH 2 - ≥ 200 mg/dL

Why Immediate Insulin? Why not MNT first?

• Blood sugar this high cannot be controlled by diet alone
• At ≥ 200 mg/dL, the fetus is already at serious risk:
  • Macrosomia already beginning
  • Fetal hyperinsulinism already triggered
• Every day of delay = fetal harm → so insulin starts same day

Starting Dose = 8 Units

• Human premix insulin 30:70
• Subcutaneous, 30 mins before breakfast

Why 8 Units specifically?

• Based on the insulin dose table from 2hr PP:

• Since ≥ 200 falls in the highest bracket → 8U is the starting dose

What else is given alongside?

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Why "No Role of Aspirin" is Specifically Mentioned

• Prevention of preeclampsia (PIH)
• Antiphospholipid syndrome

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Complete Picture Together

DIPSI Test (75g glucose, 2hr PP)
              │
    ┌─────────┼──────────┐
< 140      140-199     ≥ 200
  │           │           │
Normal      MNT         8U Insulin
Repeat at   x 2wks      + MNT
24-28 wks      │         + Weight counselling
            Goals?       (No aspirin)
           ↙    ↘
        Met    Not met
          │       │
       Continue  Metformin
        MNT      → Insulin

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One-Line Summary

140-199 = give diet 2 weeks to fix it first. ≥ 200 = start insulin immediately, no waiting - diet alone will never be enough at this level.