OGTT is most likely to diagnose all individuals with abnormal glycaemic states in the postnatal period, but resource issues and patient acceptability may limit the utility of this as a diagnostic test and so should not be routinely offered.

Fasting plasma glucose and HbA1c should not be used to determine glucose status before six weeks after delivery as levels may not be representative.

Explain to women who were diagnosed with gestational diabetes about the risks of gestational diabetes in future pregnancies and offer them testing for diabetes when planning future pregnancies.

For women who were diagnosed with gestational diabetes and whose blood glucose levels returned to normal after the birth:

• Offer lifestyle advice (including weight management, diet and exercise).
• Offer a fasting plasma glucose test 6–13 weeks after the birth to exclude diabetes (for practical reasons this might take place at the 6-week postnatal check or timed to co-ordinate with their baby vaccination schedule).
• If a fasting plasma glucose test has not been performed by 13 weeks, offer a fasting plasma glucose test, or an HbA1c test if a fasting plasma glucose test is not possible, after 13 weeks.
• Do not routinely offer a 75 g two-hour OGTT.

For women having a fasting plasma glucose test as the postnatal test:

• Advise women with a fasting plasma glucose level below 6.0 mmol/L that:
  • they have a low probability of having diabetes at present
  • they should continue to follow the lifestyle advice (including weight management, diet and exercise) given after the birth
  • they will need an annual test to check that their blood glucose levels are normal
  • they have a moderate risk of developing type 2 diabetes, and offer them advice and guidance in line with SIGN 172: Prevention, early recognition and treatment, and remission of type 2 diabetes.
• Advise women with a fasting plasma glucose level between 6.0 and 6.9 mmol/L that they are at high risk of developing type 2 diabetes, and offer them advice, guidance and interventions in line with SIGN 172: Prevention, early recognition and treatment, and remission of type 2 diabetes.
• Advise women with a fasting plasma glucose level of 7.0 mmol/L or above that they are likely to have type 2 diabetes, and offer them a diagnostic test to confirm diabetes.

For women having an HbA1c test as the postnatal test:

• Advise women with an HbA1c level below 39 mmol/mol (5.7%) that:
  • they have a low probability of having diabetes at present
  • they should continue to follow the lifestyle advice (including weight management, diet and exercise) given after the birth
  • they will need an annual test to check that their blood glucose levels are normal
  • they have a moderate risk of developing type 2 diabetes, and offer them advice and guidance in line with SIGN 172: Prevention, early recognition and treatment, and remission of type 2 diabetes.
• Advise women with an HbA1c level between 39 and 47 mmol/mol (5.7% and 6.4%) that they are at high risk of developing type 2 diabetes, and offer them advice, guidance and interventions in line with SIGN 172: Prevention, early recognition and treatment, and remission of type 2 diabetes.
• Advise women with an HbA1c level of 48 mmol/mol (6.5%) or above that they have type 2 diabetes and refer them for further care.

Rates of uptake of screening should be monitored and the effects of strategies, such as education of women and healthcare professionals, and introduction of screening co-ordinators, should be tested to evaluate improvement in uptake.

Strategies to improve uptake of screening are vital to allow early interventions and improve metabolic outcomes, for example trying to co-ordinate with other postpartum milestones such as vaccinations.