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Clinical: Managing diabetes in pregnancy

Key learning points

  • Women with pre-existing diabetes should be referred early to specialist secondary services and given pre-conception advice 
  • Diabetic pregnant women require closer monitoring by specialist diabetes and obstetric teams 
  • Women with gestational diabetes should be educated on healthy lifestyle for subsequent pregnancies and to reduce their risk of developing type 2 diabetes

Diabetes is a growing problem worldwide. Prevalence in adults has increased from 4.7% in 1980 to 8.5% in 2014.[1] In the UK, approximately 700,000 women per year give birth. Some 5% of these women have diabetes; of those 87.5% have gestational diabetes (GDM), 7.5% have type 1 diabetes and 5% have type 2.[2] Many studies, including the Confidential Enquiry into Maternal And Child Health Report, published in 2005, have shown increased risk of problems for both mother and baby in all groups.[3]

Diabetes in pregnancy causes increased risk of: 

  • Macrosomia.
  • The baby being large for gestational age. 
  • Shoulder dystocia.
  • Pre-eclampsia.
  • Foetal hypoglycaemia.
  • Stillbirth.
  • Women with pre existing diabetes also have added risks of: 
  • Miscarriage. 
  • Congenital malformations. 
  • Worsening of diabetes complications, including retinopathy and nephropathy.
  • Severe hypoglycaemia.

Tackling GDM

GDM is defined by the World Health Organization (WHO) as carbohydrate intolerance with onset or first recognition in pregnancy. The incidence varies according to how it is defined, but it is reported to range from 3-10% in developed countries.

It is accepted that GDM poses a risk of complications for mother and baby, as well as implications for the future health of the mother. Perinatal risks include shoulder dystocia, neonatal hypoglycaemia or jaundice and the physical and psychological risk for the mother of any birth trauma. The mother has an increased risk of developing type 2 diabetes in the future. In the UK, NICE recommends that women should be assessed at booking for GDM and screening should be offered at 24-28 weeks of pregnancy.

Risk assessment

Women are at risk of GDM if they:

  • Have a BMI above 30kg/m2. 
  • Previously gave birth to a macrosomic baby weighing 4.5kg or above. 
  • Have had previous gestational diabetes. 
  • Have a first-degree relative with diabetes. 
  • Are from an ethnic group with a high prevalence of diabetes.

Women with GDM in a previous pregnancy should be offered:

  • Early self-monitoring of blood glucose.
  • A 75g two-hour oral glucose tolerance test (OGTT) as soon as possible after booking (whether in the first or second trimester), and a further 75g two-hour OGTT at 24-28 weeks if the results of the first OGTT are normal.

OGTT

The woman should fast overnight and take a 75g glucose load. Diagnose GDM if the woman has either: 

  • A fasting plasma glucose level of 5.6mmol/litre or above. 
  • A two-hour plasma glucose level of 7.8mmol/litre or above.

NICE guidelines do not support universal screening of pregnant women for GDM. However, there are regional differences and some centres offer random blood glucose at booking or glucose challenge at 28 weeks of pregnancy. The Hyperglycaemia and Adverse Pregnancy Outcomes Study (HAPO) was published in 2008 and showed a correlation of risk for increased maternal glucose levels and adverse pregnancy outcomes.[4] The International Association of Diabetes and Pregnancy Groups [5] has debated lowering the diagnostic fasting value from 5.6mmol/l to 5.1mmol/l. This would have potential to double the diagnosis of GDM and the risk versus benefit needs further study.

Good practice for the management of GDM

Women with GDM require referral to a specialist joint diabetes and obstetric service for regular review. This would include:

  • An explanation of the implications of GDM – both short-term for her and the baby, as mentioned previously, and the longer-term risk of developing type 2 diabetes. 
  • Teaching of self-monitoring of blood glucose, recording readings and sharps disposal.
  • Using the same capillary plasma glucose target levels for women with GDM as for women with pre-existing diabetes as suggested by NICE 2005; however, local practices may vary.
  • Aiming for a fasting blood glucose below 5.3mmol/l, one-hour postprandial level below 7.8mmol/l or two-hour level below 6.5mmol/l.
  • Dietitian review for advice on healthy eating, including carbohydrate amounts, avoidance of refined carbohydrates and emphasis on low glycaemic index foods, tailored to individual needs.
  • Encouraging exercise, particularly after meals to improve glucose and insulin levels. [6]
  • Growth scans at 32 and 36 weeks. 

Treatment options

Women with elevated readings despite dietary and lifestyle changes should be offered either insulin or metformin, as recommended by NICE 2015. Studies have shown its benefit and follow-up of the infant up to two years later showed healthier fat distribution.[7]

However, although metformin is commonly used and is considered safe in pregnancy, some women choose not to use it because it crosses the placenta. 

These women should be treated with insulin. Women should be reassured that treatment will stop after the birth but encouraged to continue with the healthy lifestyle choices. 

Women treated with insulin should be educated in the signs, symptoms and treatment of hypoglycaemia and the guidelines for driving.

Delivery

Delivery options will be agreed jointly with the woman and obstetric team according to treatment, risks and growth scan information. Recommendations by NICE 2015 are that delivery should be either by induction of labour or caesarean section by 40+6 weeks.

Following delivery, women should be encouraged to have skin-to-skin contact and early feeding to reduce the risk of neonatal hypoglycaemia.[9] The baby should have blood glucose monitored within four hours and at regular intervals until maintaining levels above 2mmol/l pre feed. Many units have started to advocate colostrum harvesting, with hand expressing from 36 weeks so breast milk can be given after birth to reduce the risk of neonatal lypoglycaemia and admission to neonatal intensive units. The evidence is currently small-scale case studies, but large studies are currently being conducted to monitor effectiveness.

Breastfeeding has been shown to have a positive impact on reducing the progession from GDM to type 2 diabetes – women are 50% less likely to develop type 2 diabetes within 10 years if they breastfeed.[8]

Postnatal period

  • Following delivery, treatment of metformin or insulin should stop in GDM pregnancies. 
  • Women should be encouraged to return to a healthy diet, follow healthy recommendations for weight and BMI and take regular physical activity.
  • Women should be advised of the signs of hypoglycaemia, eg polyuria and polydipsia. Women should have a fasting blood glucose at six to 13 weeks to ensure diabetes has resolved.
  • The GP should offer an annual glycosylated haemoglobin (Hba1c) test.
  • Early glucose monitoring in future pregnancies.[2]

Education on healthy lifestyles is vital as GDM is the strongest risk factor for development of type 2 diabetes; 50% of women with a history of GDM will develop diabetes within five years.[2] Women should be signposted to local type 2 diabetes prevention programmes and education sessions.

Type 1 and type 2 diabetes in pregnancy

As already discussed, women with pre-existing diabetes have a three-to-five-times risk of a poor pregnancy outcome than the general population. Given the global rapid rise in type 2 diabetes and decreasing age at diagnosis, pre-conception planning is key to help reduce poor outcomes for these women.[10] Studies have shown clear evidence of improved glycaemic control and outcomes [11] when pre-pregnancy care has been given. NICE guidelines recommend pregnancy is discussed from adolescence with all diabetic women of childbearing age. Diabetes UK has produced a simple one-page pregnancy prescription that can used to help plan pregnancy.

The National Pregnancy in Diabetes (NPID) study 2015 examined all pregnancies for women with pre-existing diabetes for 2015. Key findings included:

  • There were 3,044 pregnancies in women with diabetes in 155 antenatal services. 
  • Some 46% had type 2 diabetes. 
  • More women with type 2 diabetes lived in deprived areas and tended to be older. 
  • There was a large variation in services, particularly when looking at pregnancy preparation, first contact with antenatal teams and minimising admissions to the neonatal unit. 
  • Only 55% of women with type 1 diabetes and 36% of women with type 2 had their first antenatal contact before eight weeks of pregnancy. Preterm delivery (before 37 weeks) was 40% for women with type 1 diabetes and 22% for women with type 2.
  • Only 16% of women with type 1 and 38% of women with type 2 achieved a first term trimester HbA1c of <48mmol/mol.
  • Some 46% of women with type 1 and 23% of women with type 2 diabetes were taking 5mg of folic acid prior to pregnancy.
  • Women with type 1 diabetes from deprived areas were less likely to take folic acid or have first-trimester Hba1c <48mmol/mol.
  • Positively, the stillbirth rate has significantly reduced since the CEMACH report of 20023 and the rate is now 10.7% in type 1 and 10.5% in type 2. However, this rate is still significantly higher than the rate in the general population, which stands at 4.7%.
  • The need for appointments at the antenatal clinic every one to two weeks - aiming for an Hba1c of 48mmol/l, or as close as possible without frequent hypoglycaemia, advising against pregnancy when Hba1c >86mmol/mol.
  • Discussion of the risk of deterioration of diabetes complications (retinopathy and neuropathy) in pregnancy.
  • The need for folic acid 5mg three months prior to conception until 12 weeks’ gestation to reduce neural tube defects.
  • A healthy diet with access to a dietitian for further advice on weight loss and carbohydrate counting.
  • The need for pregnancy planning and to take contraception, ideally using long acting reversible contraception (LARC) until ready for pregnancy.
  • Structured education.
  • Medication review to wean off potentially teratogenic medications.
  • For women with type 2 diabetes, possibly adding in insulin if diet, lifestyle and or metformin are not sufficient to meet HbA1c target.
  • For women with type 1 diabetes, consider transfer to insulin pump therapy if they are not reaching the target on multiple daily injections with diabetes specialist support.

Antenatal visits

Women should be seen in the antenatal clinic as soon as possible once they have a confirmed pregnancy test. In some areas, it is possible for them to self-refer, particularly if they have had pre-pregnancy care. The GP or community midwife should refer them to a diabetes in pregnancy service, ideally by telephone to ensure timely appointment within a week of confirmation of pregnancy.

As with any pregnancy, foetal movements are one of the key indicators for foetal well-being and should be discussed at each visit during the third trimester. Falling insulin requirements during this period may indicate placental insufficiency and the need for extra foetal surveillance.[14] All centres will have different organisational management, but multidisciplinary review is paramount for highlighting concerns in foetal or maternal wellbeing.[3] Joint obstetric and diabetes review are useful at key points in the pregnancy.

Postnatal care

Women should be reminded about treatment doses and optimal blood glucose targets to avoid hypoglycaemia in the postnatal period. Anecdotally, hypoglycaemia can be common when breastfeeding, but there are few studies that have solid evidence for this.[10] Postnatal discussion should include the woman’s choice of effective contraception and future pregnancy planning. The woman should be referred back to her usual diabetes care provider for ongoing care.

Future developments 

New strategies in monitoring and care are being developed to help improve outcomes. These include:

  • Increased use of technologies like smartphone applications for remote monitoring to reduce the burden on secondary care and on women attending multiple appointments. 
  • Increased services for type 2 prevention. 
  • Patient support groups and increased use of social media for patient education. 
  • Increased use of continuous glucose monitoring and insulin pump therapy. 

References 

1 World Health Organization. Diagnostic criteria and classification of diabetes mellitus 1999. Report Number WHO/NCD/NCS/99.2

2 National Institute for Health and Care Excellence Guideline NG3: Diabetes in Pregnancy. Management from preconception to the postnatal period nice.org.uk/guidance/ng3 2015 

3 Royal College of Obstetricians and Gynaecologists. Confidential Enquiry into Maternal and Child Health Stillbirth Neonatal and Post Natal Mortality 2002-2003 England, Wales and Northern Ireland. RCOG Press 2015.

4 Lynn P, Lowe P et al. Hyperglycemia and Adverse Pregnancy Outcome Study (HAPO). Diabetes Care 2012;35:574-80 

5 International Association of Diabetes and Pregnancy Study Group. Recommendations on the diagnosis and classification on hyperglycaemia in pregnancy. Diabetes Care 2010;33:676-82.

6 Avery M, Walker AJ. Acute effect of exercise on blood glucose and insulin levels in women with gestational diabetes. Journal of Maternal Fetal Medicine 2001;10:52-8.

7 Feig D, Moses R. Good for the goose and good for the gosling too? Diabetes Care 2011;34:2329-30.

8 UNICEF 2001 Implementing baby-friendly best practice standards. unicef.org.uk/wp-content/uploads/sites/2/2014/02/Baby_Friendly_guidance_2012.pdf

9 Gunderson E, Hurston S, Ning X et al. Lactation and Progression to type 2 diabetes mellitus after gestational diabetes mellitus. A prospective cohort study. Annals of Internal Medicine 2015;163:889-98.

10 McCance D. Diabetes in Pregnancy. Best Practice Research. Clinical Obs and Gynae 2015;29:685-9.

11 Murphy H, Roland J, Skinner T et al. Effectiveness of a regional prepregnancy care program in women with type 1 and type 2 diabetes. Diabetes Care 2010;33:2514-15.

12 Persson B, Hanssonu U. Hypoglycaemia in Pregnancy. Baillieres Clinical Endocrinology Metabolism 1993;7:731-9.

13 Carroll MA, Yomnans ER. Diabetic ketoacidosis in pregnancy. Critical Care Medicine 2005;33:S347-53

14 Padmanbhan S, Mclean M, Cheung N. Falling insulin requirements are associated with adverse obstetric outcomes in women with pre-existing diabetes. Diabetes Care 2014;37:2685-92.

15 Riviello C, Mello G, Jovanovic L. Breastfeeding and the basal insulin requirements in type 1 diabetic women. Endocrine Practice 2009;15:187-93.

Further reading

Australian Carbohydrate Intolerance Study in Pregnant Women (ACHIOS). Effect of treatment of gestational diabetes mellitus on pregnancy outcomes. The New England Journal of Medicine 2005;325:2477-86.

Macintosh M, Fleming K, Bailey J et al. Perinatal mortality and congenital anomalies in babies of women with type 1 or type 2 diabetes in England Wales and Northern Ireland: population based study. BMJ 2006 doi:10.1136/bmj.38856.692986.AE