Gestational Diabetes: Screening, Diet and Treatment
What gestational diabetes is and who develops it: glucose tolerance test thresholds, target blood glucose values, dietary management, insulin therapy and postnatal follow-up.
Op. Dr. Sadık Kükrer, MD
Obstetrician & Gynecologist · Adana, Türkiye
Gestational diabetes is a rise in blood glucose caused by the insulin resistance that placental hormones induce during pregnancy. It affects approximately 7–14% of pregnancies and produces no symptoms in most women. Diagnosis therefore depends on screening rather than on symptoms.
Who is at higher risk?
- Body mass index above 30.
- A first-degree relative with type 2 diabetes.
- Previous gestational diabetes or a baby weighing over 4000 g.
- Polycystic ovary syndrome.
- Maternal age over 35, or multiple pregnancy.
- A history of unexplained stillbirth.
Screening and diagnosis
Screening is offered to all women at 24–28 weeks, and at the first visit for those with risk factors.
- One-step (75 g OGTT): a single value at or above fasting 92 mg/dL, one hour 180 mg/dL or two hours 153 mg/dL confirms the diagnosis.
- Two-step: a non-fasting 50 g test; if the one-hour value exceeds 140 mg/dL, a 100 g confirmatory test follows.
Target glucose values
- Fasting: below 95 mg/dL
- One hour after meals: below 140 mg/dL
- Two hours after meals: below 120 mg/dL
Readings are usually taken four times daily — fasting and after each main meal — and recorded in a diary.
Diet and exercise
Approximately 70–85% of women achieve target values with lifestyle measures alone.
- Distribute carbohydrate across three meals and two to three snacks; do not skip meals.
- Remove sugary drinks, fruit juice, refined flour and confectionery entirely.
- Choose wholegrains, pulses, vegetables and adequate protein.
- Combine carbohydrate with protein or healthy fat to blunt the glucose rise.
- Walk briskly for 15–20 minutes after every meal.
- Insulin resistance is highest at breakfast, which should therefore be the lowest-carbohydrate meal of the day.
Medical treatment
Insulin is started if targets are not met within one to two weeks of dietary and exercise measures. It does not cross the placenta and is the safest option in pregnancy; doses often rise as pregnancy advances and are usually stopped immediately after birth. Metformin is an alternative in selected cases.
Monitoring the pregnancy
Fetal growth is assessed by ultrasound every four weeks, together with amniotic fluid volume and fetal movements. Where glucose is well controlled, birth is generally planned at 39–40 weeks. Caesarean section is discussed when the estimated fetal weight exceeds 4500 g.
After delivery
Blood glucose returns to normal in most women. A repeat 75 g OGTT at 6–12 weeks is nevertheless required, followed by screening every one to three years. The long-term risk of type 2 diabetes is substantially increased; breastfeeding, weight management and 150 minutes of exercise a week reduce it.
When to seek advice
- If more than a third of your readings exceed the targets.
- If fasting glucose is persistently above 95 mg/dL.
- With severe headache, visual disturbance or sudden swelling, which may indicate pre-eclampsia.
- If you notice reduced fetal movements.
High-risk pregnancy care in Adana
Op. Dr. Sadık Kükrer, MD provides screening for gestational diabetes, dietary planning, insulin management and comprehensive high-risk pregnancy care in Adana, Türkiye.
Frequently asked questions
When and how is the glucose tolerance test performed?+
Screening is offered between 24 and 28 weeks. In the one-step approach, a fasting sample is taken after eight hours without food, 75 g of glucose is given, and glucose is measured at one and two hours. In the two-step approach, a non-fasting 50 g screening test is performed first, followed by a 100 g confirmatory test if the result is raised.
Which values confirm the diagnosis?+
On the 75 g OGTT, a single value at or above fasting 92 mg/dL, one hour 180 mg/dL, or two hours 153 mg/dL is sufficient for diagnosis. On the 50 g screening test, a one-hour value above 140 mg/dL requires confirmatory testing.
Does gestational diabetes harm the baby?+
When untreated, it increases the risks of excessive fetal growth (macrosomia), birth trauma, preterm birth, neonatal hypoglycaemia and jaundice, as well as pre-eclampsia and caesarean birth for the mother. Most of these risks return close to background levels once glucose is well controlled.
What are the target blood glucose values?+
In general, fasting below 95 mg/dL, one hour after meals below 140 mg/dL, and two hours after meals below 120 mg/dL. Levels are usually checked four times a day: fasting and after each main meal.
What dietary changes are recommended?+
Carbohydrate should be distributed across three main meals and two to three snacks. Sugary drinks, refined flour and confectionery are removed; wholegrains, pulses, vegetables and adequate protein are preferred. Pairing carbohydrate with protein or healthy fat slows the rise in glucose, and a 15–20 minute walk after each meal lowers postprandial values appreciably.
Is insulin harmful to the baby?+
No. Insulin does not cross the placenta and is the safest treatment in pregnancy. It is started when targets are not met within one to two weeks of dietary measures, and is usually discontinued immediately after delivery.
Will my glucose return to normal after birth?+
In most women it does. A repeat 75 g OGTT is nevertheless required 6–12 weeks after delivery, with screening every one to three years thereafter. Breastfeeding, weight management and regular exercise reduce the long-term risk of type 2 diabetes.
Would you like to book a consultation?
For pregnancy monitoring, women's health, and gynecologic surgery in Adana, get in touch with Op. Dr. Sadık Kükrer.
Contact details