A postnatal test is essential to check for persisting hyperglycaemia. Unfortunately rates of postpartum screening for diabetes mellitus in women with a history of GDM are low, with fewer than half of women receiving screening.[3]American Diabetes Association. Standards of care in diabetes - 2025. Diabetes Care. 2025 Jan 1;48(Suppl 1):S344-52.
https://diabetesjournals.org/care/issue/48/Supplement_1
[51]Committee on Practice Bulletins - Obstetrics. ACOG practice bulletin no. 190: gestational diabetes mellitus. Obstet Gynecol. 2018 Feb;131(2):e49-64.
http://www.ncbi.nlm.nih.gov/pubmed/29370047?tool=bestpractice.com
[62]ACOG clinical practice update: screening for gestational and pregestational diabetes in pregnancy and postpartum. Obstet Gynecol. 2024 Jul;144(1):e20-3.
https://journals.lww.com/greenjournal/abstract/2024/07000/acog_clinical_practice_update__screening_for.34.aspx
[135]Tovar A, Chasan-Taber L, Eggleston E, et al. Postpartum screening for diabetes among women with a history of gestational diabetes mellitus. Prev Chronic Dis. 2011 Nov;8(6):A124.
https://www.cdc.gov/pcd/issues/2011/nov/11_0031.htm
http://www.ncbi.nlm.nih.gov/pubmed/22005617?tool=bestpractice.com
Studies suggest that there are multiple reasons for this, such as transportation, childcare arrangements, type of medical insurance (in countries where this applies), and lack of understanding of the risks of diabetes.[62]ACOG clinical practice update: screening for gestational and pregestational diabetes in pregnancy and postpartum. Obstet Gynecol. 2024 Jul;144(1):e20-3.
https://journals.lww.com/greenjournal/abstract/2024/07000/acog_clinical_practice_update__screening_for.34.aspx
Guidelines differ in their exact follow-up recommendations for women with GDM whose blood glucose levels have returned to normal after the birth. Check your local protocol.
In the UK, the National Institute for Health and Care Excellence (NICE) recommends the following:[4]National Institute for Health and Care Excellence. Diabetes in pregnancy: management from preconception to the postnatal period. Dec 2020 [internet publication].
https://www.nice.org.uk/guidance/ng3
It is increasingly commonplace to favour HbA1c over FPG as the postnatal test of choice. It is more convenient as it does not require a prolonged fast, it can be done at any time of day, and general practitioners are very familiar with using it to diagnose and treat type 2 diabetes.
Advise the woman as follows based on the results of the postnatal test:[4]National Institute for Health and Care Excellence. Diabetes in pregnancy: management from preconception to the postnatal period. Dec 2020 [internet publication].
https://www.nice.org.uk/guidance/ng3
FPG <6.0 mmol/L (<108 mg/dL) OR HbA1c <39 mmol/mol (<5.7%): there is a low probability she has diabetes at that moment but she has a moderate risk of developing it in the future. She should continue to follow lifestyle advice and have annual HbA1c testing.
FPG 6.0 to 6.9 mmol/L (108-124 mg/dL) OR HbA1c 39-47 mmol/mol (5.7% to 6.5%): she is at high risk of developing type 2 diabetes. Offer evidence-based advice, guidance, and interventions on preventing type 2 diabetes through diet and exercise changes and offer a referral to the NHS Diabetes Prevention Programme.
FPG ≥7.0 mmol/L (≥126 mg/dL) OR HbA1c >48 mmol/mol (>6.5%): she is likely to have type 2 diabetes. Offer confirmatory testing.
Other guidelines recommend OGTT postnatal testing rather than FPG or HbA1c. The European Society of Cardiology and American Diabetes Association (ADA) recommend OGTT 4-12 weeks postnatally for all women with GDM.[3]American Diabetes Association. Standards of care in diabetes - 2025. Diabetes Care. 2025 Jan 1;48(Suppl 1):S344-52.
https://diabetesjournals.org/care/issue/48/Supplement_1
[117]Maas AHEM, Rosano G, Cifkova R, et al. Cardiovascular health after menopause transition, pregnancy disorders, and other gynaecologic conditions: a consensus document from European cardiologists, gynaecologists, and endocrinologists. Eur Heart J. 2021 Mar 7;42(10):967-84.
https://www.doi.org/10.1093/eurheartj/ehaa1044
http://www.ncbi.nlm.nih.gov/pubmed/33495787?tool=bestpractice.com
The American College of Obstetricians and Gynecologists recommends that OGTT can be undertaken either at 4-12 weeks postpartum or in the immediate postpartum period (during the delivery hospitalisation), the latter option having demonstrated improved engagement in testing.[62]ACOG clinical practice update: screening for gestational and pregestational diabetes in pregnancy and postpartum. Obstet Gynecol. 2024 Jul;144(1):e20-3.
https://journals.lww.com/greenjournal/abstract/2024/07000/acog_clinical_practice_update__screening_for.34.aspx
For any woman with a history of GDM, ensure annual screening for cardiovascular disease and type 2 diabetes.
If in the UK, offer a referral to the NHS Diabetes Prevention Programme.[4]National Institute for Health and Care Excellence. Diabetes in pregnancy: management from preconception to the postnatal period. Dec 2020 [internet publication].
https://www.nice.org.uk/guidance/ng3
[136]Saravanan P, Diabetes in Pregnancy Working Group., Maternal Medicine Clinical Study Group., et al. Gestational diabetes: opportunities for improving maternal and child health. Lancet Diabetes Endocrinol. 2020 Sep;8(9):793-800.
http://www.ncbi.nlm.nih.gov/pubmed/32822601?tool=bestpractice.com
[137]NHS England. Healthier you: NHS Diabetes Prevention Programme – gestational diabetes mellitus (GDM) information for healthcare professionals [internet publication].
https://www.england.nhs.uk/diabetes/diabetes-prevention/healthier-you-nhs-diabetes-prevention-programme-gestational-diabetes-mellitus-gdm-information-for-healthcare-professionals
Women with GDM have a higher risk of cardiovascular events postnatally that is independent of the development of type 2 diabetes.[130]Kramer CK, Campbell S, Retnakaran R. Gestational diabetes and the risk of cardiovascular disease in women: a systematic review and meta-analysis. Diabetologia. 2019 Mar 7;62(6):905-14.
https://link.springer.com/article/10.1007%2Fs00125-019-4840-2
http://www.ncbi.nlm.nih.gov/pubmed/30843102?tool=bestpractice.com
In one UK population-based retrospective cohort study, women with a history of GDM had nearly twice the risk of developing hypertension and were diagnosed with ischaemic heart disease at a younger age compared with women without prior GDM.[138]Daly B, Toulis KA, Thomas N, et al. Increased risk of ischemic heart disease, hypertension, and type 2 diabetes in women with previous gestational diabetes mellitus, a target group in general practice for preventive interventions: a population-based cohort study. PLoS Med. 2018 Jan;15(1):e1002488.
https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002488
http://www.ncbi.nlm.nih.gov/pubmed/29337985?tool=bestpractice.com
The American Heart Association recognises prior GDM as a cardiovascular risk factor, highlighting the opportunity for early cardiovascular risk surveillance and intervention.[130]Kramer CK, Campbell S, Retnakaran R. Gestational diabetes and the risk of cardiovascular disease in women: a systematic review and meta-analysis. Diabetologia. 2019 Mar 7;62(6):905-14.
https://link.springer.com/article/10.1007%2Fs00125-019-4840-2
http://www.ncbi.nlm.nih.gov/pubmed/30843102?tool=bestpractice.com
[139]Mosca L, Benjamin EJ, Berra K, et al. Effectiveness-based guidelines for the prevention of cardiovascular disease in women - 2011 update: a guideline from the American Heart Association. Circulation. 2011 Mar 22;123(11):1243-62.
http://circ.ahajournals.org/content/123/11/1243
http://www.ncbi.nlm.nih.gov/pubmed/21325087?tool=bestpractice.com