Gestational Diabetes Mallitus (GDM) Management Summary

Gestational Diabetes Mellitus

A Simple, Illustrated Management Plan

1. Diagnosis

Diagnosed by an oral glucose tolerance test (OGTT), typically performed at 24–28 weeks of gestation (earlier if there is a prior history of GDM or other risk factors).

Diagnostic thresholds vary by protocol used locally (e.g. WHO 75-g 2-hour test vs ADA/Carpenter–Coustan 100-g 3-hour test). Follow whichever criteria are used in your unit, since the source manual predates the now widely adopted IADPSG one-step criteria.

Once diagnosed, refer promptly to a joint diabetes–obstetric antenatal clinic.

2. Initial Assessment

• Confirm gestational age accurately.
• Baseline weight/BMI, blood pressure, urinalysis.
• Assess risk factors: obesity, previous GDM, previous macrosomic baby, family history of diabetes, ethnicity.
• Educate about self-monitoring of blood glucose (SMBG), diet, and exercise.
• Involve a multidisciplinary team: obstetrician, diabetes physician, diabetes specialist nurse/midwife, and dietitian.

3. First-Line Treatment: Diet and Exercise

Diet and lifestyle change are first-line therapy for essentially all women with GDM.

Dietary principles

• Favor low glycemic index (GI) carbohydrates rather than strict restriction
• Avoid severe caloric restriction (<1200 kcal/day) — risks ketonemia
• Overweight/obese women: moderate restriction (~25 kcal/kg/day)
• Refer to a dietitian for individualized, culturally appropriate advice

Exercise

• Regular moderate activity, e.g. walking 20 min once or twice daily
• Best done after meals to blunt postprandial glucose rise
• Combined with diet, reduces need for medication

About 85% of women with GDM achieve adequate control with diet and exercise alone; roughly 15% need additional pharmacological therapy.

4. Glucose Monitoring and Targets

Home capillary blood glucose monitoring (fasting and post-meal) is standard once GDM is diagnosed.

Timing	Target
Fasting	3.5–5.9 mmol/L (63–106 mg/dL)
1-hour postprandial	< 7.8 mmol/L (140 mg/dL)
2-hour postprandial	< 6.7 mmol/L (120 mg/dL)

Evidence suggests postprandial monitoring/targets give better perinatal outcomes (lower birthweight, fewer large-for-gestational-age infants) than preprandial monitoring alone, though at the cost of somewhat higher insulin requirements when insulin is used.

Serial ultrasound assessment of fetal growth (e.g. abdominal circumference) can help guide the threshold for starting pharmacological treatment, particularly if macrosomia is suspected.

5. Escalation to Pharmacological Therapy

If glycemic targets are not met with diet and exercise alone, options include:

Insulin

• Regarded as the traditional standard of care
• Regimen (basal, prandial, or combination) individualized to the hyperglycemia pattern
• Requirements typically increase as pregnancy advances due to rising insulin resistance

Metformin

• Effective alternative to insulin; no hypoglycemia or weight gain
• Crosses the placenta freely but has not been shown to be teratogenic
• MiG trial: outcomes broadly comparable to insulin, but ~46% needed supplemental insulin; preterm birth slightly more common
• Favorable choice for overweight/obese women given weight profile and ease of use

Glyburide (Glibenclamide)

• Short-acting sulfonylurea; minimal placental transfer
• Effective in most women, but 16–21% eventually need insulin ("glyburide failure")
• Failure predictors: higher glucose challenge result, diagnosis before 25 weeks, older maternal age, multiparity, higher pretreatment fasting glucose
• Not universally available/licensed for this indication — check local practice

Choice between insulin, metformin, and glyburide should follow local guidelines, patient preference, and contraindications (e.g. metformin avoided in renal impairment).

6. Fetal Surveillance

• Serial growth ultrasound to monitor for macrosomia or growth restriction
• Increased surveillance if glycemic control is poor, macrosomia is suspected, or other risk factors are present
• Standard antenatal fetal well-being assessments otherwise apply

7. Timing and Mode of Delivery

• Diet-controlled GDM, no other complications: manage like the general obstetric population (no routine early delivery).
• Insulin-requiring GDM (or suspected macrosomia): consider elective delivery at 38–39 weeks — reduces shoulder dystocia risk without raising cesarean rates.

Individualize based on: glycemic control, estimated fetal weight/macrosomia, fetal growth restriction, maternal preference and obstetric history.

Mode of delivery: vaginal delivery is preferred where appropriate. Cesarean rates are generally higher in GDM pregnancies, partly related to maternal obesity and practice patterns rather than GDM itself.

8. Intrapartum Glycemic Management

Goal: avoid maternal hyperglycemia to reduce risk of fetal acidemia and neonatal hypoglycemia.

GDM Type	Monitoring	Target
Diet-controlled	Every 1–2 hours in established labor	< 7 mmol/L (126 mg/dL); start insulin/dextrose infusion if not met
Insulin-requiring	Hourly, IV dextrose/insulin infusion	4–7 mmol/L (72–126 mg/dL)

9. Postpartum and Neonatal Care

• Encourage early skin-to-skin contact and breastfeeding within the first hour
• Monitor neonate for hypoglycemia, especially if maternal control was suboptimal or medications were used
• Most infants do not require routine NICU admission unless there are specific concerns
• Insulin/medications for GDM are usually stopped immediately after delivery as insulin resistance resolves rapidly

10. Postpartum Follow-up (Maternal)

• Offer a 75-g OGTT at ~6 weeks postpartum to reclassify glucose tolerance
• Advise on weight management, healthy diet, and continued physical activity — reduces future risk of Type 2 diabetes
• Annual screening for diabetes with the primary care physician
• Contraception planning and repeat glucose testing before any future pregnancy (recurrence of GDM is common)
• Breastfeeding should be encouraged; no contraindications related to GDM itself

Summary Flow

This is a simplified educational summary from Swaraj Hospital and Research Institute, Bolangir and is not a substitute for local clinical guidelines or individualized clinical judgment.