Glucokinase Hyperglycaemia in Pregnancy

Glucokinase (GCK) is a gene that plays an important role in recognising how high the blood glucose is in the body. It acts as the “glucose sensor” for the pancreas, helping regulate insulin release.

Changes in the GCK gene shift this glucose-sensing threshold, leading to lifelong, mild, stable hyperglycaemia. Many affected individuals are diagnosed with diabetes, although treatment is usually unnecessary. Glucokinase diabetes is one of the familial diabetes types collectively known as MODY (maturity-onset diabetes of the young).

Source: DiabetesGenes (opens in a new tab) (accessed 20/03/2026)

Testing supports:

• Accurate diagnosis
• Avoidance of unnecessary treatment
• Appropriate pregnancy management
• Equity of access to genomic testing

Correct identification also supports fetal monitoring and consideration of non-invasive prenatal testing (NIPT).

Trusts should ensure:

• Agreement from maternity leadership and the MDT (including endocrinology and consultant obstetricians)
• Staff training on GCK hyperglycaemia and testing processes
• A local SOP or guideline
• Governance input and an agreed audit process
• Access to up-to-date patient information leaflets
• Clear arrangements for sample handling and transport to Exeter laboratory

A regional implementation guide is available to support pathway development.

No. Variant testing and NIPT for GCK hyperglycaemia are centrally funded via the NGTD. Trusts may still incur minor operational costs such as staff time, printing, blood bottles, and transport.

Management depends on gestation. If early enough, NIPT can be offered to determine whether the fetus is likely to have inherited the GCK variant.

• If inherited: babies tend to have normal birth weight and do not require special treatment.
• If not inherited: the baby may be exposed to higher maternal glucose and may be macrosomic.

NIPT analyses cell-free fetal DNA in maternal blood to determine whether the fetus has inherited the GCK variant.

Key points:

• Requires a paternal blood sample
• Can be performed from 12-31 weeks gestation
• If the father is unavailable or gestation is >31 weeks, contact Exeter for advice
• Not all GCK variants are suitable for NIPT - referrals should be targeted where results will guide pregnancy management
• Further information: https://www.diabetesgenes.org/tests-for-diabetes-subtypes/non-invasive-prenatal-testing-for-monogenic-diabetes/ (opens in a new tab)

• GCK testing: up to 42 calendar days (pregnant patients are prioritised)
• NIPT: usually within 2 weeks

There are currently no NICE or RCOG guidelines. Management should be individualised and based on an MDT-agreed pregnancy and labour care plan.

Management depends on whether the fetus is likely to have inherited the GCK variant. If inherited, diabetes monitoring and medication are not required.

Please refer to Diabetes Genes for the most up-to-date information on pregnancy management: https://www.diabetesgenes.org/what-is-mody/what-is-glucokinase-gck/ (opens in a new tab)

Routine cascade testing is not offered. If a family member already has a diabetes diagnosis, they should discuss re-evaluation of their diagnosis with their GP or endocrinology team.

Yes. People with GCK hyperglycaemia have the same risk of developing Type 2 diabetes as the general population.

Yes. Each pregnancy requires reassessment because inheritance varies. NIPT should be offered in every pregnancy where criteria are met and can be performed.

Not all GCK variants are suitable for NIPT.

There are no specific neonatal care implications. GCK hyperglycaemia is benign and does not cause long-term health complications for the baby.

Birth weight depends on inheritance:

• If inherited: babies are usually appropriate weight for gestational age
• If not inherited: babies may be larger due to higher maternal glucose exposure

Routine post-birth glucose monitoring should follow local guidelines. Postnatal genetic testing is not routinely required.