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Pregnancy and diabetes: an update

Rosemary Walker
RGN BSc(Hons) FETC
Partner
In Balance Healthcare UK
Education and Healthcare Consulting Services
E:rosebud@btinternet.com

Diabetes is a common disease that is increasing in prevalence.(1) Box 1 shows the different types of diabetes and the diagnostic criteria. It is the subject of a recently published National Service Framework (NSF) implementation programme, which will cover every aspect of care required. The standards of care to be met were published last December and include a specific reference to pregnancy and diabetes, namely:

"The NHS will develop, implement and monitor ­policies that seek to empower and support women with pre-existing diabetes and those who develop diabetes during pregnancy to optimise the outcomes of their pregnancy."(2)

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Diabetes and pregnancy
Despite recent advances in the care of diabetes before and during pregnancy, there is still a significant risk of congenital defects and perinatal mortality in babies born to mothers with diabetes.(3) These figures include mothers who have pre-existing diabetes (type 1 or 2) and those who develop diabetes during pregnancy (gestational diabetes). In either case it is vital to understand that tight glycaemic control is crucial in achieving the desired outcomes of healthy mother and baby and in reducing the tragic excess of complications (see Box 2).

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Gestational diabetes (GDM)
Gestational diabetes is the term given to diabetes that appears for the first time during pregnancy. The ­incidence is estimated at between 2% and 12%.(2) The wide range is explained by the fact that GDM is more common in some populations than others and certain conditions also increase the risk of it occurring, such as: ethnicity, increasing age, previous gestational diabetes, a family history of type 2 diabetes, a previous stillbirth, large-for-dates baby, or congenital malformation. GDM is essentially type 2 diabetes, caused by the natural insulin resistance of pregnancy revealing impaired insulin production or effect. GDM is extremely important because women are, by definition, already pregnant when it develops, so prompt identification and treatment is needed to minimise the impact of hyperglycaemia on the baby's growth and development. Women with pre-existing diabetes have the advantage of prepregnancy planning to avoid this (see below).

Although in most cases, glucose tolerance returns to normal after delivery, GDM is an important risk factor for diabetes in future pregnancies and for permanent type 2 diabetes later in life.(4) Very occasionally, type 1 diabetes is first diagnosed in pregnancy, and more commonly, but still rarely, permanent type 2 diabetes is diagnosed. This will be revealed by a diagnostic oral glucose tolerance test six weeks after the delivery (see "Postpartum care" below)

Screening for GDM
There is as yet no national screening programme for GDM, but it is well recognised that routine urinalysis at each antenatal visit, careful recognition of any hyperglycaemic symptoms, and formal oral glucose tolerance testing at 28 weeks will reveal people with GDM. There is debate about the type of test that should be performed and on whom, which it is hoped will be resolved when the results of a large study are available.(4)

Treatment of GDM
GDM requires prompt management, which includes dietary and exercise review and treatment to achieve target blood glucose levels of 4-6mmol/l premeals and up to 7.8mmol/l two hours postprandially.(5) Oral hypo­glycaemic agents are not licensed for use in pregnancy due to possible teratogenic effects, so insulin injections are required if these levels are not achieved through diet and exercise. Clearly the mother also needs to be informed (in a careful and sensitive manner) about what she needs to do in terms of monitoring and treatment and why it is important. People with GDM should be referred urgently to a specialist joint diabetes and antenatal clinic, where their visits and management will be the same as for women with pre-existing diabetes.

Pre-existing diabetes and pregnancy
The "golden rule" for women with diabetes, whether type 1 or type 2, is "don't become pregnant by accident". The first six weeks of pregnancy is the time when babies are most at risk of developing congenital defects or death due to maternal hyperglycaemia (glucose passes through the placenta but insulin does not). Since this is also a time when women may not even know they are pregnant, it is essential that this situation is avoided.

Unfortunately, however, it is estimated that a large number of pregnancies among those with diabetes are unplanned,(3) and this undoubtedly contributes to the excess morbidity and mortality. Preconceptual care for all women of childbearing age is known to reduce the risks associated with pregnancy and diabetes,(3) and the need for it is likely to be made even more explicit in the forthcoming NSF.

Preconceptual care
At least three months before conception, women should be advised to make adjustments to their eating, exercise and treatment regimens to achieve HbA1c levels of 7.0% or less. This will certainly involve capillary blood glucose monitoring at least four times daily and the titration of insulin doses according to the results. Many women transfer to a basal-bolus insulin regimen to enable them to take insulin doses to coincide with the timing or amount of their food intake. The recently developed analogue insulins such as Humalog (Eli Lilly) and Novorapid (Novo Nordisk), which work immediately and for very short periods, have undoubtedly made this titration easier and more effective.

Women with type 2 diabetes who take oral hypo­glycaemic agents often transfer to insulin to optimise their control and avoid any possible teratogenic effects at conception. It is important to remember that such intensification of diabetes control can produce more hypo­glycaemic episodes, so a careful education programme is needed. Hypoglycaemia is also more common in the first trimester (but is not harmful to a fetus), so preparation to limit the effects of this is important.

Preconceptual care also includes a review of any other medications a woman may be taking, such as ACE inhibitors, which should be stopped and replaced with agents that do not harm the fetus, and her diabetes complication status, particularly retinopathy. Pre-existing retinopathy can worsen during pregnancy and so requires careful screening before conception. Retinopathy may also develop during pregnancy, so a baseline is important to establish. Any retinopathy discovered (other than background retinopathy) should be urgently referred to an ophthalmology clinic for attention and monitoring throughout the pregnancy.

For women with diabetes, just like women without diabetes, stopping smoking, folic acid supplementation and dietary restriction of certain foods are important. The latter aspects should be discussed during a review with a dietitian, which is another essential component of preconceptual care.

Care during pregnancy and delivery
Once pregnancy is established in those with pre-existing diabetes, or GDM is diagnosed, the care is the same - demanding, frequent and vigilant but worthwhile! At least fortnightly visits to a joint antenatal and diabetes clinic are required. During these visits, careful note is taken of the blood glucose levels; medication doses, weight and blood pressure are monitored; and frequent scans are taken to assess fetal growth and development. At least once in each trimester, retinal screening must take place either at the antenatal clinic or ophthalmology department, and plans for between-visit self-care and for delivery are made. Insulin dosages in the second and third trimester of pregnancy may double or even treble, so education for self-adjustment is crucial.

Many women achieve full-term, spontaneous delivery, and that would be the situation of choice. However, the rates of emergency caesarean section among women with diabetes are significantly higher than in those without diabetes. This is due to complications that arise as a result of diabetes, including macrosomia (large-for-dates) and fetal distress. Sadly, intrauterine death late in pregnancy can occur, for reasons which remain unclear, and because of this some obstetricians understandably seek to avoid by inducing delivery before this time.

Control of blood glucose levels is just as important during labour as during pregnancy, and this is usually achieved by a continuous insulin and glucose infusion and regular blood glucose monitoring. Obviously women with diabetes require more intervention than those without diabetes, but this can be handled sensitively: the woman can self-monitor or be involved in the adjustment of insulin. Avoiding hypoglycaemia is an important aim, as this will affect the mother's participation in, and enjoyment of, the delivery.

Babies born to mothers with diabetes are sometimes prone to hypoglycaemia at birth, particularly if maternal diabetes has not been well controlled, so testing the baby's blood glucose at birth is recommended. There is no routine need for neonatal intensive care in these circumstances, as prompt feeding will rectify the ­situation. Breastfeeding is recommended for mothers with diabetes, although some changes to their insulin regimen and food intake may be required to prevent hypoglycaemia during and after feeds.(5)

Postpartum care and treatment
In most cases, GDM disappears after delivery when insulin resistance is reduced. This will be obvious by the blood glucose levels. However, everyone with diabetes that was first diagnosed during pregnancy should have an oral glucose tolerance test six weeks following delivery. This excludes a diagnosis of permanent type 2 diabetes and can be very reassuring for the mother. It is also an opportunity for discussion and education about the risks of diabetes in future pregnancies and in later life, and reducing this risk by pregnancy planning and lifestyle changes. Because of the high risk of type 2 diabetes, women who have had GDM should be tested regularly for diabetes.

For those with type 1 diabetes, insulin dosages reduce dramatically after delivery of the placenta, whose hormones are largely responsible for the increase in insulin resistance, so reduction of the level of insulin infusion is an important immediate step to prevent hypo­glycaemia. After the rigours of tight control during pregnancy, mothers can relax their monitoring and insulin titration a little, partly to prevent hypoglycaemia (especially when breastfeeding), and partly to enjoy and concentrate on their new baby! The six-week postnatal visit is a good opportunity to assess their diabetes care needs in the context of their new routine - often dosages of insulin, timing and food intake are all subject to change.

Those with type 2 diabetes may return to previous oral medication after being on insulin for the pregnancy, or they may stay on insulin injections to maintain good control. To a certain extent, the woman can make this choice, but an opportunity exists here to remind her that type 2 diabetes is a progressive disease and she may eventually need insulin treatment to control it satisfactorily.

The role of the nurse in diabetes and pregnancy
It is clear that there are a number of roles for the nurse coming into contact with women who are pregnant and who also have or develop diabetes.

Educator
Information should be available about the importance of a planned pregnancy in those with diabetes. It should be displayed in areas where women have access to it, such as health centres, antenatal clinics and pharmacies. Information for people who might be at risk of developing GDM should also be available. Well-woman clinics, immunisation sessions (for mothers themselves or when they come with their children) and antenatal clinics are ideal opportunities to identify those who might be at risk of GDM and advise them about reducing risk factors and planning pregnancy. Discussing and providing information about future risks of type 2 diabetes is essential for those who have had previous GDM and can be instigated at follow-up postnatal visits.

Monitor
Once diabetes and pregnancy are established, providing appropriate care and documentation with regard to blood glucose testing, weight, urine and blood pressure measurements, and retinopathy screening are aspects in which the nurse can make an important contribution to healthy outcomes.

Liaison and referral agent
Liaison with medical, midwifery and diabetes specialist nurse colleagues may be necessary if the nurse has any concerns. Linked to this role is that of referral agent: the nurse is in a good position to ensure that the mother has received the care recommended, such as a visit with the dietitian before conception or at diagnosis of GDM, prompt referral to a specialist diabetes and antenatal clinic, and follow-up appointments for oral glucose tolerance tests where indicated.

Conclusion
This article has provided an update on the role of the nurse who may come into contact with a pregnant woman with diabetes. By ensuring practice reflects the care required, nurses can make a very important contribution to minimising the still-­significant risks associated with diabetes and pregnancy.

References

  1. Williams G, Pickup JC. Handbook of diabetes. 2nd ed. Oxford: Blackwell Science; 1999.
  2. Department of Health. The National Service Framework for diabetes: ­standards. London: Department of Health; 2001.
  3. Hawthorne G, Modder J. Maternity services for women with diabetes in the UK. Diab Med 2002;19 Suppl 4:50-5.
  4. Hanna FWF, Peters JR. Screening for gestational diabetes: past, present and future. Diab Med 2002;19:351-8.
  5. Diabetes UK. Pregnancy and diabetes. London: Diabetes UK; 2002.

Resources
National Service Framework for Diabetes
W:www.doh.gov.uk/nsf/diabetes

Diabetes UK
10 Parkway
London NW1 7AA
T:020 7424 1000
W:www.diabetes.org.uk