Introduction > Classification > Gestational diabetes
Gestational diabetes
Gestational diabetes (pregnancy diabetes) is represented by any degree of glucose intolerance (blood glucose levels higher than normal), with onset or first recognition during pregnancy. This means that the concerned woman did not know about diabetes existence before pregnancy (even though diabetes might be present for years) and she discovered a high blood glucose (sugar in the blood) during pregnancy.
If blood sugar is higher than that considered normal, but lower than the threshold for classic diabetes, gestational diabetes is still diagnosed because this situation is present during pregnancy. In other words, blood sugar during pregnancy should be within normal range, otherwise the diagnosis of gestational diabetes is made.
Gestational diabetes is a diagnosis that exists only during pregnancy. After birth, the diagnosis of gestational diabetes disappears (by convention). If high blood glucose level persists above the thresholds for diabetes a diagnosis of type 1, type 2 or secondary diabetes is made. The woman is considered to no longer have diabetes if her blood glucose returns to normal after delivery (including during glucose tolerance test).
Gestational diabetes is a condition that can heal, is not necessarily an incurable diagnosis, as with other forms of diabetes. Although diabetes can disappear after giving birth, it can reoccur with a future pregnancy. Although a little questionable, diabetes complicating a pregnancy in a woman who had been diagnosed with gestational diabetes at a previous pregnancy is still called gestational diabetes.
All women diagnosed with gestational diabetes should undergo an oral glucose tolerance test with 75g glucose 6-12 weeks after birth to determine the persistence of any degree of glucose metabolism impairment.
The discovery of gestational diabetes that later disappears after birth is associated with an increased risk of developing type 2 diabetes during life. For this reason, it is recommended that all women who had been diagnosed with gestational diabetes to be later tested for diabetes at least once every 3 years.
Gestational diabetes is present in approximately 4% of pregnancies if diagnostic criteria valid until 2010 are used. This figure however is about to grow significantly due to the new (2011) diagnostic criteria. The importance of the smallest increases in blood glucose on pregnancy complications is now generally recognized.
There are several types of gestational diabetes:
- new onset type 1 diabetes
- long running, previously undiagnosed, type 2 diabetes
- long running, previously undiagnosed, secondary diabetes
- pregnancy induced diabetes
Diagnosis of gestational diabetes remains only during pregnancy. Its persistence after birth leads to reformulation as type 1, type 2 (most common) or secondary diabetes, depending on the situation. If blood sugar returns to normal after birth the woman has no longer the diagnosis of diabetes, but she still has a very high risk of developing gestational diabetes in a subsequent pregnancy or “classic” diabetes outside of pregnancy.
During pregnancy the placenta takes care of the child and its secreted hormones contribute to a normal fetal growth. At the same time, these hormones block the tissue action of insulin secreted by the woman pancreas. This problem is called insulin resistance and is responsible for increased difficulty of the mother to use the insulin for glucose disposal. The need for insulin may increase under these conditions up to three times.
Gestational diabetes occurs when the mother’s body cannot produce and use as much insulin as required by the presence of pregnancy. Without insulin, glucose cannot leave the blood in order to be converted in energy into the cells. Glucose accumulates in the blood, a condition called hyperglycemia.
The main risk factors for gestational diabetes are:
- obesity
- mother’s age
- previous birth of a child weighting > 4.5 kg
- gestational diabetes in a previous pregnancy
- history of polycystic ovary syndrome
- first degree relatives with diabetes
- family origins in populations with high frequency of diabetes (South Asia, Caribbean, Middle East)
Diagnosis of gestational diabetes has recently been changed and it can be found here.
If not diagnosed and treated with highest caution, gestational diabetes will affect the fetus, it will increase the risk of complications during pregnancy, birth and immediately afterwards, and also on the long term, in childhood or young adulthood.
If the fetus is affected in the first trimester, spontaneous abortion can occur, and also a delay in early fetal development and birth defects. If hyperglycemia occurs in the second quarter of pregnancy behavioral and intellectual disorders may arise. If glycemic mediated damage occurs in the last quarter, the child may become heavier than normal at birth and will have an increased risk for obesity and diabetes in life.
Increased glucose level received by the fetus through the placenta stimulates fetal secretion of insulin in order to get rid of this excessive sugar. Receiving a greater amount of energy than is normally needed for growth, the fetus will use it to produce fat and gain weight, becoming a bigger and heavier than normal baby at birth (= macrosomia). These babies may have problems with their shoulders during birth and difficulty in breathing after birth. Because insulin secretion is high and glucose intake low after birth, a significantly decrease in blood glucose below normal (hypoglycemia) can occur. It has been shown that babies with high levels of insulin secretion are at high risk for becoming obese and developing type 2 diabetes in adulthood.
Gestational diabetes is often asymptomatic. After the diagnosis was made based on blood glucose values from the 24-28 week compulsory testing, many women remember a higher frequency of the following symptoms: dry mouth, thirst, frequent urination, fatigue, nausea, vomiting, urinary infections and vision disturbances.
Many of these symptoms are somewhat normal in pregnancy and women do not give enough importance until gestational diabetes is diagnosed. As a consequence, there is an absolute necessity for gestational diabetes testing during week 24-28 of pregnancy.
All women diagnosed with gestational diabetes should monitor their blood sugar and fasting blood sugar (on an empty stomach, in the morning) and two hours after a meal, preferably using a finger glucose testing. It is recommended to obtain fasting blood sugar
The first therapeutic step is diet and exercise. Exercise should be tailored to condition of pregnancy. It can involve for example only the upper limbs exercising, including light weight lifting.
If glycemic control cannot be achieved through diet and exercise, appropriate pharmacological treatment for diabetes should be started. Metformin and glibenclamide are formally contraindicated in pregnancy, as well as other diabetes pills. Metformin and glibenclamide have been used in pregnancy with the woman’s consent and entirely assumed risk and nothing bad happened. They are not yet worldwide approved for use in pregnancy (according to the current prospectus).
The only approved pharmacological way to lower blood glucose during pregnancy is insulin. It can be used only during pregnancy to obtain the desired glycemic control and stopped soon after birth.
