Gestational Diabetes Screening — OGTT at 24–28 Weeks
Gestational diabetes affects 10–20% of pregnancies in India and is largely asymptomatic — making universal screening essential. The 75g OGTT at 24–28 weeks identifies women whose blood glucose handling requires intervention to protect maternal and fetal outcomes.
What is Gestational Diabetes?
GDM is glucose intolerance first identified during pregnancy. Hormones from the placenta cause insulin resistance, and some women cannot compensate with enough insulin production. Most cases resolve after delivery, but GDM increases lifetime maternal type 2 diabetes risk and short-term fetal complications.
Why Universal Screening?
GDM has no specific symptoms. Selective screening (only “high-risk” women) misses approximately 30% of cases. Indian women have higher GDM prevalence than Western populations. WHO, FIGO, and Indian DIPSI guidelines all recommend universal OGTT screening for all pregnant women.
The 75g Oral Glucose Tolerance Test (OGTT)
Performed at 24–28 weeks. Fasting blood glucose drawn, then 75g glucose drink consumed, then 1-hour and 2-hour blood glucose measurements. WHO/IADPSG cutoffs: fasting ≥92 mg/dL, 1-hour ≥180 mg/dL, 2-hour ≥153 mg/dL. ANY one value at or above cutoff diagnoses GDM. DIPSI single-step (non-fasting) is also used in resource-limited settings.
Earlier Screening for High-Risk Women
Earlier OGTT (at booking or 16–20 weeks) for: BMI ≥25, prior GDM, prior macrosomic baby, family history of diabetes (first-degree relative), PCOS, prior unexplained stillbirth, glycosuria, age ≥35.
GDM Management — Tight Control Matters
Step 1: nutritional therapy + structured exercise. Most mild GDM is controlled this way. Self-monitoring of blood glucose with home glucometer. Targets: fasting <95, 1-hour post-meal <140, 2-hour post-meal <120 mg/dL. Step 2: pharmacologic therapy (insulin first-line, metformin in select cases) added if targets not met. Tight control significantly reduces macrosomia, shoulder dystocia, neonatal hypoglycaemia, and birth complications.
Frequently Asked Questions
Do I really need the OGTT if I feel fine?
Yes. GDM is asymptomatic. Detection only happens via screening. Late detection means missing the window where intervention prevents complications.
Will GDM affect my baby?
Untreated/poorly controlled GDM increases risk of fetal macrosomia, birth trauma, neonatal hypoglycaemia, NICU admission, and long-term offspring metabolic risk. With tight control, outcomes are excellent.
Will I need to inject insulin?
Most GDM (60–80%) is managed with diet and exercise alone. Insulin is reserved for cases where targets cannot be met with lifestyle alone. When needed, it is the safest option for both mother and baby.
Does GDM mean I will have lifelong diabetes?
GDM typically resolves after delivery, but it identifies you as high-risk for type 2 diabetes lifetime. We recommend OGTT at 6–12 weeks postpartum and annual screening thereafter. Lifestyle intervention significantly reduces conversion rate.
Can I prevent GDM?
Pre-pregnancy weight optimisation, regular physical activity, and reduced refined carbohydrate intake reduce risk but do not eliminate it. Genetics and pregnancy hormones are major drivers beyond lifestyle control.
What if I am already diabetic before pregnancy?
Pre-existing (Type 1 or Type 2) diabetes requires very different management — preconception counselling, tighter glycaemic control, more intensive surveillance. This is NOT gestational diabetes; it is pregnancy in a woman with diabetes.
Dr. Priyadatt Patel
Senior Gynecologist · Advanced Laparoscopic Surgeon · IVF and Endometriosis Programme Lead
MS OBGyn · Pregnancy Care · Advanced Gynaecological Ultrasound · Fertility Preservation
ESHRE / ESGE / AAGL / ASRM guideline-aligned practice. 3D Karl Storz precision technique. Fertility-preservation-first philosophy. Evidence-based decisions, honest counselling, long-term outcomes orientation.
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