2 Research recommendations
- 2.1 Preconception care for women with diabetes: insulin pump therapy and continuous glucose monitoring
- 2.2 Testing for gestational diabetes
- 2.3 Barriers to achieving blood glucose targets before and during pregnancy
- 2.4 Risk of fetal death for women with diabetes
- 2.5 Postnatal treatment for women diagnosed with gestational diabetes
The Guideline Development Group has made the following recommendations for research, based on its review of evidence, to improve NICE guidance and patient care in the future. The Guideline Development Group's full set of research recommendations is detailed in the full guideline.
2.1 Preconception care for women with diabetes: insulin pump therapy and continuous glucose monitoring
What are the roles of insulin pump therapy (continuous subcutaneous insulin infusion) and continuous glucose monitoring in helping women with diabetes to achieve blood glucose targets before pregnancy?
Babies born to women with diabetes have a high risk of having congenital malformations and this risk is greater if blood glucose control is poor around the time of conception. However, lowering the risk to that of women without diabetes would require normalisation of blood glucose levels, and this is difficult to achieve without increasing the risk of serious hypoglycaemia. Insulin pump therapy and continuous glucose monitoring have been shown to reduce both blood glucose levels and rates of hypoglycaemia in the non‑pregnant population, but it is uncertain if this holds true before conception and in early pregnancy. There is therefore an urgent need to test the effectiveness and acceptability of these technologies in women with diabetes who are planning pregnancy. This would be best undertaken in a randomised controlled trial of women with diabetes who are trying to conceive. Women would be allocated to receive either conventional care (self‑monitoring of blood glucose and insulin adjustment) or insulin pump therapy and continuous glucose monitoring.
When should testing for gestational diabetes take place – in the first or second trimester?
Conventionally, testing for gestational diabetes takes place in the second trimester. Intervention has been shown to improve outcomes for women diagnosed with gestational diabetes. However, maternal age and obesity are increasing, and some women (especially those from populations with a high incidence of type 2 diabetes) enter pregnancy with undiagnosed type 2 diabetes, but may not be tested for diabetes until the second trimester. This exposes the woman and the fetus to risks resulting from early and prolonged maternal hyperglycaemia. It is presumed that this is associated with increased morbidity. UK population studies are needed to establish the incidence of glucose intolerance in women in the first trimester Well‑designed randomised controlled trials are needed to establish if testing, diagnosis and intervention in the first rather than the second trimester improves maternal, fetal and neonatal outcomes, including fetal hyperinsulinaemia.
What are the barriers that women experience to achieving blood glucose targets?
It is vital for normal fetal development in the first trimester that women with pre‑existing diabetes achieve good blood glucose control both before and during pregnancy. Good control also helps to prevent macrosomia and other complications in the third trimester in women with pre‑existing or gestational diabetes. Whereas many women manage to achieve blood glucose targets, a proportion of women continue to find it difficult to do so. A number of factors could be involved, such as health beliefs, a poor understanding of the importance of good blood glucose control, an inability to be able to comply with a demanding regimen of blood glucose testing up to 7 times a day, and the need to adjust insulin dosage. A better understanding of the barriers in this cohort of women is needed so that healthcare professionals can work to overcome them. Robust qualitative studies are needed to explore these barriers, with the aim of improving blood glucose control and fetal outcomes in pregnancy for women with pre‑existing diabetes and women with gestational diabetes.
How can fetuses at risk of intrauterine death be identified in women with diabetes?
Unexpected intrauterine death remains a significant contributor to perinatal mortality in pregnant women with diabetes. Conventional tests of fetal wellbeing (umbilical artery Doppler ultrasound, cardiotocography and other biophysical tests) have been shown to have poor sensitivity for predicting such events. Alternative approaches that include measurements of erythropoietin in the amniotic fluid and MRI spectroscopy may be effective, but there is currently insufficient clinical evidence to evaluate them. Well‑designed randomised controlled trials that are sufficiently powered are needed to determine whether these approaches are clinically and cost effective.
Are there effective long‑term pharmacological interventions to prevent the onset of type 2 diabetes that can be recommended postnatally for women who have been diagnosed with gestational diabetes?
Gestational diabetes is one of the strongest risk factors for the subsequent development of type 2 diabetes: up to 50% of women diagnosed with gestational diabetes develop type 2 diabetes within 5 years of the birth. There are some data suggesting that changes in diet and exercise, with or without metformin, can prevent type 2 diabetes developing in non‑pregnant middle‑aged people with glucose intolerance, but there are no studies specifically in women with a past history of gestational diabetes. There is thus an urgent need to investigate what interventions may delay or prevent type 2 diabetes developing in this high‑risk population of women. Undertaking a formal randomised controlled trial involving long‑term outcomes is often not feasible in practice. However, it would be possible to have a quasi‑randomised study comparing 2 populations of women with similar demographic profiles who had gestational diabetes. One population would be encouraged at their annual check to follow a specific diet and exercise regime and those in the other population would not. The incidence of the development of type 2 diabetes in the 2 groups at 5, 10 and 20 years would be compared.