This site is intended for health professionals only

Diabetes and pregnancy: why the concern?

Jackie Patterson
RGN NDN FETC
Diabetes Specialist Nurse
Guildford and Waverley PCT
E:jackie.patterson@royalsurrey.nhs.uk

There are two types of pregnancy in diabetes to be considered - pregnancy in those with established diabetes, and diabetes that occurs during pregnancy and may go away afterwards (gestational diabetes mellitus [GDM]). The management of each is different, and while nurses in general practice may have little to do with the expert overall management of these conditions, it is wise to be well informed. More routine care of people with diabetes is occurring within general practice, and nurses need to be able to deal effectively with requests for support from pregnant women or those considering pregnancy.

Why is it of concern?
Diabetes is the most common pre-existing medical ­disorder complicating pregnancy in the UK.(1) Approximately one pregnant woman in 250 has pre-existing diabetes. This is associated with increased risks for both mother and baby.(2) Women with pre-existing diabetes are much more likely to lose their baby than women who do not have diabetes. In the UK, perinatal mortality rates among the babies of diabetic mothers are up to five times higher than in the general population.(3)
Fetal insulin is an anabolic hormone. Maternal hyperglycaemia causes fetal hyperinsulinaemia, which results in accelerated fetal growth and macrosomia.(4) The term macrosomia is used to describe an infant greater than 4,000g or 4,500g; however, this weight may be appropriate for sex, gestational age and ethnicity. Some ethnic groups, such as Asians, produce smaller infants than white Europeans, in whom approximately 10% of normal, full-term male infants weigh more than 4,000g. A perceived large-for-dates infant may influence obstetric intervention.

Pregnancy in established diabetes
Pregnancy in women with diabetes is regarded as high risk, and ideally women should be seen in specialist prepregnancy clinics to ensure that they are as well prepared as possible. They should be advised that they will be subject to frequent antenatal visits. They should have access to specialist members of the team - an obstetrician, physician, specialist dietitian, midwife and diabetes specialist nurse.
Type 1 diabetes (formerly insulin-dependent diabetes; juvenile-onset diabetes) is more common than type 2 diabetes (formerly noninsulin-dependent or maturity-onset diabetes) during the reproductive years. However, the increasing prevalence of type 2 diabetes in younger people means that we shall increasingly see more pregnancies complicated by this condition, especially in areas with a high Asian or African-Caribbean population.
Despite improvements in the clinical management of pregnant women with diabetes, Stott et al demonstrated that good glycaemic control alone did not prevent macrosomic or large-for-gestational-age infants.(5) They acknowledged, however, that it was of proven benefit in reducing perinatal mortality and morbidity.

Planning a pregnancy - advice to give
All healthcare professionals in contact with women of childbearing age with diabetes should be aware of the importance of prepregnancy care and of local arrangements for delivery, and should share this information with the woman. The woman and her partner should feel part of the care team and be offered education to allow them to make informed choices about their ­management.
All women with diabetes should be prescribed prepregnancy folate supplementation continuing up to 12 weeks' gestation.(3)
Tight glycaemic control should be advocated - Diabetes UK advises 4.4-6.1mmol/l before meals and less than 8.6mmol/l two hours after meals.(6) However, this may vary between centres. It is imperative that any home monitoring meter is up-to-date and accurate; laboratory samples will also be required. Nurses should ensure that pregnant women understand how to achieve these stringent glucose levels and support them through self-adjustment of therapy if they are on insulin. More support will be required for women commencing insulin in pregnancy, and the nurse may wish to liaise with the local diabetes specialist nurse to share the care.
Tight blood glucose control and the needs of the fetus increase the chance of hypoglycaemia. Nurses should ensure that women, and those close to them, have had the opportunity to discuss the recognition, management and treatment of hypoglycaemia. Partners should be supplied with and taught how to use a glucagon injection.
Hypoglycaemic unawareness can become a significant concern for a few women in pregnancy, and these women may need to be advised to monitor before driving or, in severe cases, give up driving for the duration of the pregnancy. Conversely, measures to prevent ketoacidosis due to high blood glucose levels should be taught. Ketoacidosis is preventable by frequent monitoring, controlling levels with adequate medication and self-adjustment of insulin. Nurses should ensure that pregnant women with diabetes have ketone testing strips and know how and when to use them.

Treatment
Most women with diabetes who become pregnant will be treated with a basal/bolus insulin regimen. This means at least four injections of insulin per day, usually rapid-acting insulin with meals and either one or two injections of long-acting insulin. In exceptional circumstances it may be necessary to use insulin pump therapy. No insulin has a licence in pregnancy, but people with type 1 diabetes must continue to receive this form of treatment. Glargine insulin (Lantus; Aventis) has no safety record in pregnancy, and therefore some centres may recommend changing to another regimen.(6)
It is necessary for pregnant women to monitor their blood glucose levels very frequently. How frequently will depend on their level of control, but they may be asked to test before and two hours after meals and occasionally during the night. Diabetes UK suggests targets of 4.4-6.1mmol/l before meals and less than 8.6mmol/l two hours after meals.(6)
Some women taking oral hypoglycaemic agents (OHAs) may continue this treatment in pregnancy, but this must be the subject of discussion between the woman and her specialist team.(6) OHAs may have a teratogenic effect and are normally stopped before conception.

Gestational diabetes mellitus
GDM is defined as glucose intolerance that is first diagnosed during pregnancy. Between 2% and 10% of women develop GDM.(7) There is confusion surrounding the diagnosis of and screening for GDM,(8) and there continues to be much debate about the definition, significance and management of the condition. Jarrett suggested that GDM fails to meet the criteria for screening and "that the disorder should be well defined and that it should be serious and there must be an effective way to treat or prevent it which could not be achieved without screening".(9,10) Others argue that the benefits to the child in terms of reduced macrosomia, neonatal hypoglycaemia, operative delivery, increased glucose intolerance during puberty, and increased risk of diabetes later in life are significant.(11,12) Equally, the benefits to the mother in terms of identifying a greatly increased risk of type 2 diabetes cannot be ignored.
During pregnancy, changes occur in maternal carbohydrate metabolism to optimise fetal nutrition and growth.(13) The production of increasing concentrations of hormones such as oestrogen, progesterone and human placental lactogen causes a decline in insulin sensitivity and a corresponding small increase in postprandial blood glucose levels. This decline in insulin sensitivity necessitates an increase in maternal insulin secretion to maintain normoglycaemia. Women with insufficient b-cell function become glucose intolerant towards the end of pregnancy. That this glucose intolerance indicates a vulnerability to future diabetes is widely accepted;(7) however, the immediate risk to the mother during the index pregnancy and the risk to the fetus are uncertain and are also the subject of much debate.
The National Institute for Clinical Excellence (NICE) advises that routine screening for GDM is not supported by clinical evidence, and is not recommended.(7) It is, however, essential for nurses to have a high degree of suspicion in at-risk groups such as the obese, those with a strong family history of diabetes, and women of Asian or African- Caribbean origin. The glucose tolerance test is regarded as the gold standard for the diagnosis of GDM where screening has proved positive. However, there is still inconsistency in diagnostic levels (see Table 1).(7)

[[NIP19_table1_48]]

[[nip19_box1_48]]

As in type 1 diabetes, GDM carries an increased risk of large-for-dates babies. Whether or not excellent blood glucose control during this time will alleviate the problem is still the subject of discussion.
In an editorial by Dornhorst and Girling in the New England Journal of Medicine,(14) the authors stated that: "… the threshold at which glucose intolerance adversely affects the course of pregnancy and increases the risk of future diabetes in the mother and her child is not known … we think the optimal care for women with gestational diabetes remains to be defined."

Treatment
Initially, GDM is treated with diet. If this fails to achieve tight control of blood glucose, insulin therapy will be required. As many as 15-20% may need insulin therapy, but this can generally be stopped postpartum.(12) Hypertension can pose a significant concern in women with type 2 diabetes who become pregnant and will require additional monitoring.
In all cases of pregnancy in diabetes and GDM, screening for retinopathy and nephropathy is included in the care plan.

The future
Many women who develop GDM will develop type 2 diabetes in later life and should be advised to take regular exercise, maintain a healthy weight and be aware of symptoms. They should also be offered annual screening for diabetes.

Conclusion
Pregnancy that is complicated by diabetes should not be managed by general practice. However, the general practice team may be the point of contact for women planning a pregnancy, and it is important that they are aware of the implications of diabetes and pregnancy and are able to give sound advice and refer the women on appropriately.

Practice ­pointers

  • Diabetes is the most common pre-existing medical disorder complicating pregnancy
  • Nurses in general practice should be able to offer preconception advice to women with diabetes
  • Diabetes in ­pregnancy and gestational diabetes require specialist care
  • There is no current agreement on screening for gestational diabetes
  • Nursesin general practice providing routine care to people with diabetesshould include ­hypoglycaemic, hyperglycaemic and glucose monitoring intheir education plans

References

  1. Hawthorne G, Modder J. Maternity services for women with diabetes in the UK. Diabet Med 2002;19:50-5.
  2. Department of Health. National Service Framework for Diabetes: Standards. London:?DoH; 2001.
  3. Scottish Intercollegiate Guidelines Network. Management of diabetes in pregnancy. Guideline 55, Section 8. Edinburgh: SIGN; 2002.
  4. Jovanovic-Petersen I, Petersen C, Reed G, et al. The National Institute of Child Health Development - diabetes in early pregnancy study. Maternal post prandial glucose levels and infant birth weight. Am J Obstet Gynecol 1991;164:103-11.
  5. Stott A, Nik H, Platt MJ, et al. Glycaemic control in pregnant women with type 1 diabetes and fetal ­macrosomia. Pract Diabetes Int 2004;21:215-20.
  6. Diabetes UK. Recommendations for the management of pregnant women with diabetes (including ­gestational diabetes). London: Diabetes UK; 2004.
  7. National Institute for Clinical Excellence. Antenatal care. Routine care for the healthy pregnant woman. Clinical Guideline. London: NICE; 2003. Available from URL: http://www.rcog.org.uk/resources/ Public/AntenatalCare.pdf
  8. Jardine Brown C, Dawson A, Dodds R, et al. Report of the Pregnancy and Neonatal Care Group. Diabet Med 1996;13:S43-53.
  9. Jarrett R. Gestational diabetes: a non entity? BMJ 1993;306:37-8.
  10. Jarrett R. Should we screen for gestational diabetes? BMJ 1997;313:736-7.
  11. Soares J, Dornhorst A, Beard R. The case for screening for gestational diabetes. BMJ 1997;315:737-9.
  12. Dornhorst A, Chan S. The elusive diagnosis of gestational diabetes. Diabet Med 1998;15:7-10.
  13. Buchanan T, Dornhorst A. The metabolic stress of pregnancy. In: Dornhorst A, Hadden D, editors. Diabetes and pregnancy: an ­international approach to diagnosis and management. Chichester: Wiley; 1996. p. 45-62.
  14. Dornhorst D, Girling J. Editorial. N Engl J Med 1995;333:1281-3.