Gestational diabetes (GDM) is the development of of hyperglycaemia (high blood glucose levels) during pregnancy. A common pregnancy complication, gestational diabetes is serious and may result in further complications and risks for both mother and baby.
Making the lifestyle changes necessary for optimal blood glucose control is very important and some cases, insulin may be necessary. While gestational diabetes resolves after pregnancy, type 2 diabetes becomes an increased risk for both mother and baby. This indicates that a healthy lifestyle must continue beyond pregnancy and must be passed on to the child.
Who is at risk?
Prganant women who are overweight or obese, over 35 years of age or have a family history of diabetes (type 1 or type 2 or GDM) are at increased risk of developing gestational diabetes.
Other risk factors include having had a previous baby born at larger than 4.5 kg, a diagnosis of prediabetes prior to pregnancy and a history of complications during previous pregnancies.
Diagnosis of Gestational Diabetes
A glucose tolerance test is required to diagnose gestational diabetes and is usually done between 24 and 28 weeks of pregnancy. This may be done earlier in women considered to be at high risk.
The World Health Organisation (WHO) gives the following guidance for diagnosis using and oral glucose test of 75g of glucose dissolved in water
- On waking (fasting) : > 5.1 mmo/l
- 1 hour post meal: > 10.0 mmol/l
- 2 hours post meal: > 8.4 mmol/l
A diagnosis of gestational diabetes needs to be viewed as a serious condition as uncontrolled blood glucose levels can result in the following negative outcomes:
- preterm delivery (spontaneous or planned)
- caesarean section delivery (planned or emergency)
- foetal or infant weight greater than normal for gestational age
- admission to a neonatal intensive care unit
- neonatal hypoglycaemia (low blood glucose levels in baby after birth)
- hyperbilirubinaemia (jaundice in baby)
- congenital malformations (malformations present from birth)
- pregnancy induced hypertension (high blood pressure)
- macrosomia (infant born at more than 4.5 kg)
Managing gestational diabetes for optimal control of blood glucose levels and the reduced risk of complications requires dietary changes, self monitoring of blood glucose levels and increased safe physical exercise unless otherwise indicated.
The recommended optimal range for the level glucose in the blood is between 4 and 7 mmol/l. The primary goal for the management of diabetes is to consistently achieve this target. If a reading is above the recommended 7 mmol/l for a 2 hours post meal test, an adjustment needs to be made to that meal time the next day. If readings remain high, this must be reported.
The nutrition management of gestational diabetes is not only beneficial for blood glucose control but also for the overall health of the baby, weight management and the developement of healthy eating habits for the postpartum period and beyond. Losing pregnacy weight and more importantly preventing weight gain post pregnancy is essential to the prevention of the onset of type 2 diabetes post pregnancy or later in life.
A follow up glucose tolerance test should be done between 4 and 12 weeks postpartum. This is accoring to the World Health Organisation which also recommend that women with a history of GDM should do a oral glucose tolerance test every 2 years. The reason for this is the 7-fold increase in the risk of developing type 2 diabetes following gestational diabetes, relative to the risk prior to pregnancy.
A note on carbohydrate
Carbohydrate food sources should not be completely eliminated from the diet. Fibre rich, whole plants foods, contain too much nutrient value to be ignored. The choice of carbohydrate food sources is however very important to the successful management of gestational diabetes.
Pairing carbohydrate food sources with lean sources of protein or plant fat sources helps to lessen blood glucose spikes following a meal or snack. Doing so will also lead to increased satiety.
Working closely with a dietitian can help strike the balance between optimal nutrition, optimal bloood glucose control and optimal weight gain for pregnancy.
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