Diabetes Pregnancy
Improved diabetes control in early pregnancy can reduce the incidence of congenital malformations and early spontaneous fetal loss.
Pre-pregnancy Assessment
See patients with their partner if possible and provide with written information
- Take a full medical, obstetrical and gynaecological history
- Review current medication. Note ACE Inhibitors, Statins and other teratogenic drugs should be discontinued
- Prescribe Folic Acid 5mg daily for at least a month pre-conception and during first trimester. The usual “over the counter” dose is 400mcg daily and this is insufficient in women with diabetes because of an increased risk of neural tube defects.
- Assess for presence of diabetes complications and treat blood pressure if required
- Check rubella antibody status, thyroid biochemistry and urinalysis
- Advise on diet and weight reduction if relevant and strongly discourage smoking
- Educate on the importance of good glycaemic control and avoidance of ketoacidosis
- Aim to obtain HbA1c near to the non-diabetic range, while avoiding hypoglycaemia
- Instruct partners to recognise and manage hypoglycaemia
- In women with type 2 diabetes, insulin initiation may be required in those receiving oral hypoglycaemic agents or where it is not possible to obtain good control with diet alone and exercise. Please contact the diabetes team about this. Metformin and glibenclamide are the only OHA’s permissible to use during pregnancy.
Women who are well-controlled and free of complications can be advised to stop contraception and to keep a record of periods. Other women may require additional time to optimise glycaemic control or to have investigation and treatment of complications.
Advise patients to perform a pregnancy test if there is a lapse of five weeks between periods and contact a Diabetes Specialist Nurse soon after obtaining a positive result
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Ante-natal Care
- Ante-natal care should be hospital-based, from a multi-disciplinary team
- Individualise insulin regimens and recommend 4-times daily glucose monitoring.
- Aim to maintain glucose 4-6 mmol/L pre meal and < 7 2 hour post prandially. The HbA1c should be within the normal non-diabetic range
- Remember insulin requirements increase progressively from the 2nd trimester until the last month of gestation, when a slight fall-off may be noted
- For patients with pregestational diabetes Aspirin 75mg should be started by about week 12 of pregnancy to reduce the risk of pre-eclampsia
- Hypoglycaemia and loss of awareness is common in early pregnancy. Women who lose awareness of hypoglycaemia in pregnancy should be advised to stop driving until their warning symptoms return to normal. Hypoglycaemia does not appear to have long-term adverse effects on fetal development
- Ketoacidosis can cause fetal death at any stage. All women should test urine for ketones if their blood glucose is high (>10), if vomiting occurs or if they are unwell. They should be advised to contact their Diabetes Specialist Nurse, hospital antenatal team or GP if persistent ketonuria is present as admission for intravenous fluid and insulin may be required. Patients may be instructed to check blood ketones, and should seek urgent help if blood ketones are > 0.6 mmol/L.
- All women should have regular retinal screening and measurement of blood pressure and renal function, as retinopathy and nephropathy may deteriorate during pregnancy.
- Patients generally attend for ante-natal care at intervals of 2-4 weeks from booking up to 28 weeks, every 2 weeks until 36 weeks and thereafter weekly until delivery.
Delivery
- The timing of delivery is individualised; in women with good diabetes control and no complications, the pregnancy may be continued to 38-40 weeks
- Caesarian section rates are often higher than in non-diabetic women (approximately double)
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Post-natal Care
- Insulin requirements fall dramatically after delivery, therefore reduce insulin doses immediately to pre-pregnancy levels, to avoid hypoglycaemia
- Encourage slightly higher blood glucose levels than during pregnancy
- In breast-feeding mothers, reduce insulin dose further once lactation is established
- Discuss contraception while the patient is still in hospital
- All women should be seen by the diabetes pregnancy care team six weeks after delivery
Gestational Diabetes
Gestational diabetes mellitus (GDM) affects up to 20% of pregnancies and is defined as carbohydrate intolerance of variable severity, with onset or first recognition in pregnancy. A screening programme for GDM should identify those pregnant women with blood glucose levels that are associated with an adverse fetal outcome or an increased risk of future diabetes in the mother.
- In normal women during pregnancy, the range for fasting blood glucose is lower than in non-pregnant women
- Glycosuria with normal blood glucose levels is common, due to a lowering of the renal glucose threshold.
Screening for GDM
- Urine should be tested at each antenatal visit for glycosuria (preferably fasting sample)
- Timed laboratory venous plasma glucose measurements should be made
- At booking visit
- At 28 weeks gestation
- In cases when glycosuria 1+ or more is detected
- A 75g oral glucose tolerance test (OGTT) should be performed if the plasma glucose is
- > 5.5 mmol/L 2 hours or more after food
- > 7.0 mmol/L within 2 hours of food
- Diagnosis of GDM is made on OGTT as follows:
- Fasting glucose ≥ 5.1 mmol/L or
- 1 hour glucose ≥ 10 mmol/L
- 2 hour glucose ≥ 8.5 mmol/L
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Management of GDM
- Dietary advice should be given in all cases.
- Refer to Combined Diabetes Antenatal team at Perth Royal Infirmary or Ninewells Hospital
- If fasting or pre-prandial glucose is consistently greater than 6mmol/L, insulin should be introduced (usually b.d. regimen will suffice)
- Glucose targets are similar to patients with established diabetes
- In most cases, insulin and self blood glucose monitoring can be discontinued at delivery
- Ensure that normoglycaemia returns after delivery
- A 75g OGTT should be performed at around 6 weeks post-partum and the results interpreted according to WHO criteria
- The condition is associated with an increased risk of future diabetes (usually Type 2 DM)
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After GDM
- She is more likely to get gestational diabetes in any future pregnancy.
- She is at increased risk of developing diabetes in the future with a 50% rate of Type 2 diabetes over 10 years and a low rate of Type 1 diabetes, particularly in patients who have been thin. We would thus recommend checking an annual fasting glucose and if there is any rise in the fasting glucose level to perform a glucose tolerance test. This is to ensure she does not have undiagnosed diabetes.
- If she is overweight then the best way to avoid developing diabetes in the future is to keep her weight down with lifestyle measures of diet and exercise.
- If after a reasonable trial she is having difficulty keeping her weight down and the weight is increasing, then pharmacological therapy may be considered. Metformin or Acarbose as have both been shown to be useful in trials to prevent/delay the onset of Type 2 diabetes. You may wish to consider these agents if required.
Check fasting plasma glucose annually in women with a history of GDM to identify asymptomatic diabetes and screen for the condition in a future pregnancy.
Women with previous GDM should be made aware of the benefits of exercise and importance of weight control, to avoid the development diabetes
NHS Tayside Guideline for Post-Partum Follow-up of Patients with Gestational Diabetes
Contraception
Contraception should be discussed with all diabetes women in the child-bearing age group.
1. Combined Oral Contraceptive Pill (OCP)
- Low dose oestrogen preparations are safe for use in the majority of diabetes women
- They may cause a rise in BP and raise HDL cholesterol and triglycerides (oestrogen).
- Monitor BP, weight and HbA1c twice yearly, assess lipids annually and discontinue if hypertension or deteriorating lipid metabolism occurs.
- Avoid when complications of diabetes or risk factors for vascular disease present or in older women (> 35 years). However a value judgement should be made in women for whom avoidance of pregnancy is essential.
2. Progestogen-Only Pill (POP)
- Advantages are lack of vascular side-effects or effects on lipid metabolism.
- Omission is more likely to result in pregnancy than with the combined OCP.
- Irregular periods or inter-menstrual bleeding may occur
- Injectable and implantable progestogens are suitable for some patients, particularly if compliance is an issue. However deterioration in glycaemic control may occur.
3. Intra-Uterine Contraceptive Device
- The main advantage is the lack of metabolic effects
- There is a theoretical risk of infection causing salpingitis
- Most suitable after the final planned pregnancy
4. Mechanical Contraception
- Not recommended if it is essential to avoid pregnancy due to the high failure rate.
5. Sterilisation
- Sterilisation may be advised if further pregnancy represents a serious risk to health.
- Obesity adds to the risk of the procedure and the failure rate is 0-0.5 per women years
Hormone Replacement Therapy in Diabetes
Diabetes is not a contraindication to the use of Hormone Replacement Therapy. Advice on use of HRT in any woman applies equally to women with diabetes.
RCPE Consensus Statement on Hormone Replacement Therapy October 2003
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