Monitoring
A postnatal test is essential to check for persisting hyperglycaemia. 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 recommends the following:[4]
For women diagnosed with gestational diabetes and whose blood glucose levels have returned to normal after the birth:
Offer lifestyle advice (including weight control, diet, and exercise) - including providing support to lose weight if overweight and to lose any excess gestational weight gained
Offer a fasting plasma glucose (FPG) test or HbA1c 6 to 13 weeks after the birth to exclude diabetes (for practical reasons this can take place at the 6-week postnatal check or baby’s immunisation visit)
Do not routinely offer a 75-g 2‑hour oral glucose tolerance test (OGTT).
It is increasingly commonplace to prefer 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. It can be done at 8 to 12 weeks postnatally.
Advise the woman as follows based on the results of the postnatal test:[4]
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 to 47 mmol/mol (5.7%-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.
For any woman with a history of GDM, ensure annual screening for cardiovascular disease and type 2 diabetes.
Other guidelines recommend OGTT postnatal testing rather than FPG or HbA1c. For example, the European Society of Cardiology and the American Diabetes Association recommend an OGTT test at 4 to 12 weeks postnatally for all women with GDM.[3][97]
Women with GDM have a higher risk of cardiovascular events postnatally that is independent of the development of type 2 diabetes.[111] Women diagnosed with GDM had almost a twofold higher risk of developing hypertension and have ischaemic heart disease at a relatively young age compared with women without a previous diagnosis of GDM.[96] A history of GDM is considered a cardiovascular risk factor by the American Heart Association and this therefore provides an opportunity for early cardiovascular risk surveillance modification.[111][112] Gestational diabetes should be treated as a pre-cardiovascular disease state and the management strategy should be aimed at comprehensive identification and systematic treatment of cardiovascular risk factors beyond the prevention of type 2 diabetes.[110]
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