SECTION II: MANAGEMENT OF DISORDERS AND SPECIAL SITUATIONS
The term ‘gestational diabetes’ defines women with onset or first recognition of abnormal glucose tolerance during pregnancy. Gestational diabetes affects between 2 and 10 percent of women during pregnancy.
Pregnancy is characterized by insulin resistance and hyperinsulinemia, which may predispose some women to develop diabetes. The resistance stems from placental secretion of diabetogenic hormones (including growth hormone, placental lactogen, and progesterone) as well as increased maternal adipose deposition, decreased physical activity and increased caloric intake.
It is important to recognize and treat gestational diabetes as soon as possible to minimize the risk of adverse outcomes and complications in the baby.
Adverse outcomes include:
- Fetal macrosomia
- Fetal organomegaly (hepatomegaly, cardiomegaly)
- Birth trauma
- Operative delivery
- Perinatal mortality
- Neonatal respiratory problems and metabolic complications (e.g. hypoglycemia, hyperbilirubinemia, hypocalcemia)
If abnormally high blood sugar levels are present during organogenesis because of overt (also termed pre-gestational) diabetes, there is an increased risk of miscarriage and congenital anomalies.
There are also potential long-term consequences to the infant, such as development of obesity and diabetes during childhood, impaired fine and gross motor functions, and higher rates of inattention and/or hyperactivity.
Women with pre-gestational diabetes mellitus will benefit from counseling and information sharing on the importance of a planned pregnancy and health professionals should work closely with them to optimize health status prior to conception.
Their evaluation should include information on:
- the duration and type of diabetes,
- history of acute complications (infections, ketoacidosis, severe hypoglycemia)
- chronic complications (retinopathy, nephropathy, neuropathy, hypertension, cardiovascular disease)
- current and past glucose control
- physical activity
- gynaecologic and obstetric history
It is useful to involve a diabetes educator and a registered dietitian and to include the woman’s partner or other members of her family.
Glycemic control plays an important role in reducing the frequency of fetal and neonatal complications.
To be most effective, glycemic control needs to be achieved pre-conceptionally. Therefore, a major goal of preconception care of women with diabetes is to evaluate glycemic control and recommend adjustments in diet, medications, and lifestyle, as needed, to achieve euglycemia (levels within the normal range).
Haemoglobin A1c: A pre-pregnancy target of <7 percent is recommended
Glycosylated haemoglobin (A1c) values, which reflect the average blood glucose concentration over the previous 8 to 12 weeks, are useful in evaluating a woman’s glycemic control before conception and throughout pregnancy.
Folic Acid Supplementation
Supplementation with a minimum of 0.4 to 0.8 mg of folic acid, with higher doses (4 mg) if there are additional risk factors for neural tube defects (NTDs). Such increased risk occurs if there was an affected baby in a previous pregnancy; a family history of NTD; diabetes and/or obesity.
Antenatal appointments for women with diabetes should consider routine antenatal care as well as care specifically for diabetes management.
Care should be hospital based and ideally provided by a multidisciplinary team which would include a nurse, obstetrician and dietitian, and depending upon availability, a diabetes educator, a perinatologist, an internist and an endocrinologist.
The key elements in management of pregnancies complicated by diabetes are:
- Achieving and maintaining excellent glycemic control
- Screening, monitoring, and intervention for maternal medical complications (eg, retinopathy, nephropathy, hypertension, cardiovascular disease, ketoacidosis, thyroid disease)
- Monitoring of, and intervention for, fetal and obstetrical complications (eg, congenital anomalies, preeclampsia, macrosomia)
Achieving and Maintaining Excellent Glycemic Control
This involves diet, physical activity, patient education, and, if necessary, pharmaceutical medical therapies should be used.
Diet and Physical Activity
- The cornerstone of care of a pregnancy that is complicated by diabetes is proper diet. Elements of dietary therapy include management of the quantity and quality of nutrient intake.
- Physical activity is another key component in diabetic care; cardiovascular physical activity reduces insulin resistance.
- The physiologic constraints of pregnancy should be taken into consideration when counseling women about physical activity and in clinics which offer physical activity classes, physician access should be available.
- The supine position should be avoided since vena cava compression by the gravid uterus may occur and activities which require a great deal of balance must be avoided (to prevent injuries from falls).
- Women with gestational diabetes should measure their blood glucose concentration two to four times daily, fasting and one or two hours after the start (‘first bite’) of each meal, to determine whether hyperglycemia severe enough to increase fetal risk is occurring.
- Results should be recorded in a glucose log, along with dietary information to be shared with healthcare providers.
|Target Levels for blood glucose concentration:|
|Fasting||≤95 mg/dL (5.3 mmol/L)|
|One-hour postprandial||≤140 mg/dL (7.8 mmol/L)|
|Two-hour postprandial||≤120 mg/dL (6.7 mmol/L)|
Screening test for diabetes in pregnancy: the most commonly performed screening test is the O’Sullivan’s test, which is positive if the blood glucose level exceeds 140mg/dL (7.8 mmol/L), 1 hour after 50gm glucose oral intake.
A positive test should lead to a formal glucose tolerance test.
- If normoglycemia cannot be achieved and maintained by physical activity and nutritional interventions, then anti-hyperglycemic agents should be initiated.
- There are two options in pregnant patients who require medical therapy aimed at controlling blood glucose: insulin and selected oral anti-hyperglycemic agents.
Screening, Monitoring, and Intervention for Maternal Medical Complications
Routine prenatal laboratory evaluations are performed. Urinalysis and culture for assessment of asymptomatic bacteriuria are important because of a 3-5 fold increased risk in diabetic women.
Screen for End Organ Damage
Women with diabetes should undergo medical review and be screened for end organ damage (if this has not been undertaken pre-conceptually) e.g. assess renal function and assess eyes for proliferative retinopathy etc. The following tests are recommended to identify these associated complications:
- 24-hour urine collection for protein and creatinine clearance
- Serum creatinine
- 12-lead ECG
- Ophthalmologic examination (if not done within the last 12 months).
- Thyroid function tests (particularly if type 1 diabetes)
The value of ongoing education during subsequent visits cannot be overstated. Improved patient knowledge and understanding leads to greater compliance with the treatment program. Each clinic visit should be viewed as an educational opportunity.
Blood Pressure and Urinalysis
- These should be assessed at each visit.
- Women with diabetes probably have an increased risk of pregnancy-induced hypertension, so close monitoring of the blood pressure is recommended
Monitoring of and Intervention for Fetal and Obstetrical Complications
- Women should be offered the routine first-trimester scan (11–14 weeks of gestation) to confirm dates and viability.
- Detailed ‘anomaly’ scan at 20 weeks’ gestation.
- Ultrasound at 36 weeks’ gestation to assess macrosomia, polyhydramnios and fetal biophysical profile.
Non-Stress Testing/Biophysical Profile
- Antenatal testing twice weekly, usually initiated at about 32 weeks of gestation.
- It is generally recommended that women who require insulin or an oral antihyperglycemic agent to maintain euglycemia are managed the same way as women with pre-gestational diabetes.
- Women who are euglycemic with diet and physical activity alone and who have no other pregnancy complications (eg, no macrosomia, preeclampsia, growth restriction, polyhydramnios or oligohydramnios) do not appear to be at increased risk of stillbirth.
- Therefore, for women with impeccable glucose control, antepartum fetal surveillance with nonstress testing or biophysical profile scoring is not required.
When blood sugar levels are close to normal during pregnancy and there are no other complications, the ideal time to deliver is at 38 weeks’ gestation. In certain instances, the woman can be allowed to continue up to 40 weeks of pregnancy, but she should not be allowed to go post dates.
If spontaneous labour has not occurred, then labour should be induced, providing that there are no contraindications to a vaginal birth.
After delivery, most women with gestational diabetes will experience normal blood sugar levels and they do not require further medical treatment with insulin or oral agents. Most women can return to their pre-pregnancy diet, and they should be encouraged to breastfeed. If the blood sugar level is normal after delivery, it is important to test for type 2 diabetes at six weeks postpartum. Testing usually includes a two-hour glucose tolerance test.
Risk for Gestational Diabetes
One-third to two-thirds of women who have gestational diabetes in one pregnancy will have it again in a later pregnancy.
Risk of Type 2 Diabetes
Women with gestational diabetes have an increased risk of developing type 2 diabetes later in life, especially if the woman has other risk factors (eg, obesity, family history of type 2 diabetes). The risk of developing type 2 diabetes is greatly affected by body weight. Women who are obese have a 50 to 75 percent risk of type 2 diabetes, while women who are a normal weight have a less-than-25 percent risk.
It is recommended that all women with a history of gestational diabetes have testing for type 2 diabetes at least every three years after their pregnancy. Women who have gestational diabetes after age 45 should have testing once per year.
Women with a history of gestational diabetes have no limitations to the type of contraception after pregnancy.