Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX
For pregnant women, the screening protocols for gestational diabetes mellitus (GDM) involve assessing risk factors and conducting specific tests.
- Risk Assessment: At the booking appointment, assess for risk factors including a BMI above 30 kg/m², a previous macrosomic baby weighing 4.5 kg or more, previous gestational diabetes, a family history of diabetes (first-degree relative), or an ethnicity with a high prevalence of diabetes NICE NG3,NICE CKS,NICE CKS. Women with any of these risk factors should be offered testing for gestational diabetes NICE NG3. Do not use fasting plasma glucose, random blood glucose, HbA1c, glucose challenge test, or urinalysis for glucose to assess the risk of developing GDM NICE NG3.
- Testing Protocol: The recommended test for gestational diabetes is the 75-g 2-hour oral glucose tolerance test (OGTT) NICE NG3.
- Timing of Testing:
- For women who have had gestational diabetes in a previous pregnancy, offer early self-monitoring of blood glucose or a 75-g 2-hour OGTT as soon as possible after booking (whether in the first or second trimester) NICE NG3. A further 75-g 2-hour OGTT should be offered at 24 to 28 weeks if the results of the first OGTT are normal NICE NG3.
- For women with any other risk factors for gestational diabetes, a 75-g 2-hour OGTT should be offered at 24 to 28 weeks NICE NG3.
- Consider further testing to exclude gestational diabetes in women who have glycosuria of 2+ or above on one occasion, or glycosuria of 1+ or above on two or more occasions, during routine antenatal care NICE NG3.
- Diagnosis: Gestational diabetes is diagnosed if the woman has either a fasting plasma glucose level of 5.6 mmol/litre or above, or a 2-hour plasma glucose level of 7.8 mmol/litre or above NICE NG3. When GDM is diagnosed, women should be offered a review with the joint diabetes and antenatal clinic within one week, and their primary healthcare team should be informed NICE NG3.