Gestational diabetes is when a women without pre-existing diabetes develops high blood glucose (sugar) levels during pregnancy. It starts when your body is not able to make and use all the insulin it needs for pregnancy. Without enough insulin, glucose builds up to high levels in your blood stream. The extra glucose crosses the placenta, giving your baby high glucose levels. Untreated or poorly controlled gestational diabetes can hurt your baby. The extra glucose can lead to macrosomia, or a ‘fat’ baby, which increases the risk of complications during labour and shortly after birth. In addition, high glucose levels raises your risk of high blood pressure, and preeclampsia — a serious complication of pregnancy.
Because gestational diabetes can hurt you and your baby, you need to start treatment. For many women diet and physical activity are enough to keep blood glucose levels in the normal range, however for some additional treatment options need to be considered.
Your own insulin production can be ‘topped up’ with an injection of insulin at the meal time when the blood glucose levels are rising out of the target range. You may need to take insulin at one or all of your meals. Sometimes the insulin you produce in-between your meals and overnight may need to be ‘topped up’ and this may require an extra slower acting insulin at bedtime. You will be advised when and how much insulin you will need to take by the diabetes team. The insulin you take does not pass across the placenta to your baby.
Balancing the insulin dose with the food you eat, and your activity levels, will keep your blood glucose levels in the normal range which means your baby will receive the right amount of energy/food to encourage normal growth. The dose of insulin will go up as your pregnancy progresses. Blood glucose monitoring is very important as it shows us when a change in the dose is needed to keep the levels in the target range.
Metformin is a tablet that has been used successfully for almost 40 years to treat diabetes out of pregnancy. It is increasingly being used during pregnancy as an alternative or in addition to insulin.
Metformin works by allowing insulin to work more effectively, so a smaller amount of insulin will work better. This can mean that your own limited insulin production may be enough to regulate blood glucose levels with Metformin to ‘boost’ its action.
Metformin can also be useful in addition to insulin injections. Using them together can keep insulin doses lower which can help prevent excessive pregnancy weight gain and therefore improve pregnancy outcomes.
Unlike insulin, Metformin does pass across the placenta. There have been a number of studies to look at the safety of Metformin in pregnancy and your diabetes doctor in clinic will be happy to discuss this with you. Metformin is not an option for everyone; there are also certain medical conditions or pregnancy complications that may mean insulin would be a better choice.
Some people (2 out of every 10) experience side effects from taking Metformin such as stomach upsets; these can be minimised by starting on a low dose, and building the dose up slowly and by taking the tablet with or immediately after food.
In most women treatment with Metformin and insulin can be stopped immediately after delivery. However, it is important to check blood glucose levels for a couple of days after delivery to ensure normal glucose levels.
Nationella riktlinjer för diabetesvård. Stockholm: Socialstyrelsen; 2015. Available at: http://www.socialstyrelsen.se/nationellariktlinjerfordiabetesvard