There are two types of diabetes in pregnancy. Sometimes, diabetes can present for the first time during a pregnancy; this is called gestational diabetes mellitus (GDM) and is usually diagnosed by a routine test about halfway through the pregnancy. A diabetes diagnosis during pregnancy may go away after delivery. Alternatively, you could already have type 1 or type 2 diabetes before pregnancy; in these cases, you need to plan carefully for your pregnancy with this pre-existing condition.
What is gestational diabetes?
GDM affects from 5% to 20% of pregnancies and is detected by a routine test that all women should have at 24 to 28 weeks of pregnancy. If the primary care team suspects a woman may have GDM, they may check earlier or repeat the test, if negative the first time. The screening test is a non-fasting sugar drink followed by a blood test, 1 hour later. If this is elevated, another test is done that is also a sugary drink after a fasting blood test, and then additional blood tests are done 1 and 2 hours after the drink. If the results show elevated blood sugars, then the woman is usually referred to a diabetes education team to develop a meal plan and blood glucose monitoring schedule.
If blood sugars are not able to be kept within the healthy targeted range by following the meal plan, then medication is prescribed. This is usually insulin, although much less commonly, metformin may be used. Insulin is a safe and effective method for managing blood sugars in pregnancy. Women develop diabetes in pregnancy because pregnancy is a state where there is more demand for insulin, due to the increasing resistance to insulin as the pregnancy progresses, as a result of the hormones in pregnancy.
What are the risk factors for developing gestational diabetes?
These are similar to risk factors for developing diabetes in the non-pregnant state, such as having a relative with diabetes, belonging to an ethnic group where diabetes is more common (such as Indigenous Canadians, Hispanic, Indo-Canadians), being overweight or obese, being older, having had GDM during a previous pregnancy or giving birth to a large baby (greater than 9 pounds/4000 g) and having polycystic ovary syndrome.
What are the complications of gestational diabetes?
If GDM goes undetected or untreated, the higher sugars in the mother’s blood can affect the baby. This could result in a larger baby that causes difficulties at the time of birth and a higher C-section or forceps rate. The baby has more chance of spending time in the intensive care unit due to trouble breathing or low blood sugars. However, GDM can be treated fairly easily with a combination of a healthy meal plan and sometimes insulin, and these complications can be avoided. Unlike women with pre-existing type 1 or type 2 diabetes, birth defects are not a concern as the higher blood sugars do not generally happen until after 20 weeks of pregnancy, and this is after the baby has developed their organs.
What is the best way to manage gestational diabetes?
Nowhere in medicine is a team so important, as well as communication amongst team members. At the centre of the team is the woman who is pregnant, with her family supports, her primary caregiver, her obstetrical care person and her diabetes education team. It can be a stressful time being diagnosed with GDM. A woman is expecting a normal pregnancy and now in a short period of time she needs to learn a different way of eating, monitoring her blood sugars, staying physically active and worrying about the effect GDM may have on her pregnancy, delivery and baby.
The most important first step is seeing a dietitian to help with a meal plan. This plan generally consists of calories spread throughout the day, low glycemic index food choices, limiting sugary drinks and having adequate protein. Blood glucose monitoring is taught and then reviewed within a short period of time to see if the meal plan is adequate for blood sugar control. Often the woman is also taught to test urine ketones.This is to check if she is getting adequate calories.
If blood glucose levels are above target while following the meal plan and getting adequate calories, usually night-time longer-acting insulin is introduced to help with elevated morning glucose readings. If blood sugars are elevated after a meal, a short-acting insulin is added prior to whichever meal is elevated. All of this can be tricky with pregnancy given that some women experience nausea or have trouble eating certain foods, which can be difficult when using insulin. In addition, normal activity can be limited.
Is there any follow up required after delivery?
If you have had GDM, it is essential to be screened for diabetes before your next pregnancy. GDM can increase the chances of developing type 2 diabetes. It is therefore critical to know if you are about to enter your next pregnancy and already have diabetes, with elevated sugars during the time that the baby is developing in the first trimester. It is also very important that if you have had GDM that you follow up after the baby is born to see if the diabetes has gone away. Usually, this involves a 2-hour sugar drink test that is done 6 weeks to 6 months after delivery.
You need to continue to be checked regularly (every 1 to 3 years) to see if you have developed diabetes, for your own health, and certainly before another pregnancy, to protect your next child from high sugars if you have developed diabetes prior to that pregnancy. If you have had diabetes in pregnancy, it will help to reach your ideal weight prior to the next pregnancy in order to reduce the risk of developing diabetes.
