---
title: "Gestational diabetes: Symptoms & Treatment | HealthAnswers"
description: "Gestational diabetes — high blood sugar in pregnancy, glucose tolerance test, monitoring, and reducing risks to mother and baby."
url: https://healthanswers.co.uk/conditions/gestational-diabetes/
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---

# Gestational diabetes: Symptoms & Treatment | HealthAnswers

Health A–Z

Gestational diabetes — high blood sugar in pregnancy, glucose tolerance test, monitoring, and reducing risks to mother and baby.

Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026

## Quick answer

What is gestational diabetes? Gestational diabetes is high blood sugar developing during pregnancy — usually in second or third trimester — and usually resolves after birth. All pregnant women in UK offered screening — oral glucose tolerance test (OGTT) at 24 to 28 weeks if low risk, earlier if risk factors. Managed with diet, blood glucose monitoring, metformin or insulin if needed. Increases risk of large baby, pre-eclampsia, and type 2 diabetes later — follow-up glucose test after birth essential.

General UK health information, not a diagnosis. In an emergency call 999 ; for urgent advice use [NHS 111](https://111.nhs.uk/) (GP out-of-hours in Northern Ireland).

On this page 7 sections

## Key facts about gestational diabetes

- Gestational diabetes affects about 5% of UK pregnancies — rising with obesity and older mothers.
- Hormones from placenta cause insulin resistance — pancreas may not compensate sufficiently.
- Most women manage with diet and exercise — tablets or insulin if targets not met.
- Good glucose control reduces macrosomia (large baby), shoulder dystocia, and neonatal hypoglycaemia.
- 50% risk of type 2 diabetes within 5 to 10 years after gestational diabetes — lifestyle prevention key.

## Gestational diabetes (GDM) — pregnancy sugar

**Gestational diabetes mellitus** is **diabetes first recognised in pregnancy** — not **pre-existing diabetes** (different pathway).

**~5% UK pregnancies** — **rising** with **maternal [obesity](https://healthanswers.co.uk/conditions/weight-loss-and-obesity/)** and **age**.

**Placenta produces human placental lactogen and other hormones** → **physiological [insulin](https://healthanswers.co.uk/treatments/insulin/) resistance** — **GDM when pancreas cannot keep up**.

## Who gets screened

**All pregnant women** — **risk stratification**:

**Early OGTT (booking)** if:

- previous GDM

- BMI ≥30 (or ≥27.5 South Asian)

- previous macrosomic baby ≥4.5kg

- first-degree relative diabetes

- PCOS

- high-risk ethnicity

**Universal OGTT 24–28 weeks** if not already diagnosed

## Diagnosis thresholds (NICE)

**75g OGTT:**

- fasting ≥5.6 mmol/L , OR

- 2-hour ≥7.8 mmol/L

**One abnormal value** — **GDM**

## Why it matters

**Maternal:**

- [pre-eclampsia](https://healthanswers.co.uk/conditions/pre-eclampsia/) risk

- polyhydramnios

- caesarean — large baby

- future type 2 diabetes

**Fetal/neonatal:**

- macrosomia

- shoulder dystocia — obstetric emergency

- neonatal hypoglycaemia — baby’s insulin high when cord cut

- respiratory distress

- stillbirth — rare with care

**Good control** — **outcomes near normal**.

## Management

### Blood glucose monitoring

**Capillary testing** — **fasting and 1-hour post-meal** (or 2-hour per local protocol)

**Targets (NICE):**

- fasting <5.3 mmol/L

- 1-hour post-meal <7.8 or 2-hour <6.4

### Lifestyle

- carbohydrate consistency — don’t eliminate — baby needs glucose

- walk after meals

- dietitian — specialist antenatal diabetes clinic

### Medication if targets missed

**[Metformin](https://healthanswers.co.uk/treatments/metformin/)** — **crosses placenta minimally** — **NICE option**

**Insulin** — **gold standard if metformin insufficient or contraindicated**

**Glibenclamide** — **selected centres** — **less first-line**

### Obstetric care

- growth scans

- induction timing — often 38–40 weeks if on insulin/macrosomia — individual

- hospital birth if insulin — protocol varies

## After birth

**Placenta gone** — **insulin resistance drops** — **stop diabetes meds** unless told otherwise

**Fasting glucose 6–13 weeks** — **OGTT if borderline**

**If normal:**

- annual [HbA1c](https://healthanswers.co.uk/tests/hba1c/) or glucose — lifelong

- lifestyle — halve type 2 risk

**Breastfeeding** — **encouraged**

## GDM vs type 2 in pregnancy

**Pre-existing diabetes** — **higher baseline risk** — **preconception HbA1c optimisation** — **retinopathy check**

See [type 2 diabetes](https://healthanswers.co.uk/conditions/type-2-diabetes/) and [PCOS](https://healthanswers.co.uk/conditions/polycystic-ovary-syndrome/) — **shared risk**.

GDM is **common, manageable, temporary** — **missed postnatal test** misses **lifetime diabetes warning**.

## ! When to see a GP about gestational diabetes

Attend all antenatal appointments — screening is routine. If diagnosed, diabetes midwife and clinic monitor closely. Seek urgent maternity assessment for reduced fetal movements, severe headache/visual disturbance (pre-eclampsia), or very high home glucose readings. Fasting glucose test 6 to 13 weeks postpartum — do not miss — identifies persistent diabetes.

## Common questions about gestational diabetes

What causes gestational diabetes? Placental hormones block insulin action — insulin resistance rises in pregnancy. If pancreas cannot produce enough extra insulin, blood sugar rises. Risk factors — BMI over 30, previous gestational diabetes, family history type 2, polycystic ovary syndrome, South Asian/Black/Caribbean/Middle Eastern ethnicity, previous large baby over 4.5kg. How is gestational diabetes tested? Oral glucose tolerance test — fasting blood sample, drink 75g glucose drink, second sample 2 hours later. Diagnosed if fasting ≥5.6 mmol/L or 2-hour ≥7.8 mmol/L (NICE thresholds). Earlier testing if previous GDM or glycosuria. Does gestational diabetes harm the baby? Poorly controlled glucose crosses placenta — baby grows large (macrosomia), increases birth injury and shoulder dystocia risk, neonatal low blood sugar after delivery, jaundice, stillbirth risk elevated though absolute risk low with good care. Good control minimises complications. How is gestational diabetes treated? Blood glucose monitoring — fasting and post-meal targets. Diet — spaced carbohydrates, portion control. Exercise if safe in pregnancy. Metformin or insulin if lifestyle insufficient — both safe in pregnancy when indicated. Team includes obstetrician, diabetes midwife, dietitian. Does gestational diabetes go away after birth? Usually resolves immediately or within days after placenta delivered. Fasting glucose test 6 to 13 weeks postpartum — if normal, annual diabetes screening recommended lifelong due to high type 2 risk. Breastfeeding may modestly reduce later diabetes risk.

## Sources

- [NHS — Gestational diabetes](https://www.nhs.uk/conditions/gestational-diabetes/)
- [NICE — Diabetes in pregnancy](https://www.nice.org.uk/guidance/ng3)

## How we reviewed this page

Medically reviewed by the [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/)

First published 14 June 2026 Medically reviewed 3 July 2026 Next review due 3 July 2029 or sooner if NHS or NICE guidance changes

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