Up to 15% of pregnant women will develop gestational diabetes
Gestational diabetes is a type of diabetes that occurs during pregnancy, usually around 24-28 weeks. About 15% of pregnant women will develop gestational diabetes. Gestational diabetes occurs due to insulin resistance causing higher than normal blood glucose levels during pregnancy. The hormones produced by the placenta for the baby's growth and development also impair a mother's insulin. A mother's body needs to produce 2–3 times the usual amount of insulin to overcome this resistance. Higher than normal blood glucose level in the mother leads to glucose crossing the placenta to the baby. This can cause the baby to have high blood glucose levels as well.
Women most at risk of gestational diabetes include gestational diabetes in a previous pregnancy, a previous large baby (more than 4500g), if you are aged 40 years and over, or if you are of Aboriginal and Torres Strait Islander background. Also at higher risk are women of Asian, Indian, Middle Eastern, African, Pacific Islander backgrounds, those with a family history of type 2 diabetes and/or mother or sister with a history of gestational diabetes, and those women who have previously shown increased blood glucose levels or insulin resistance. Other factors that may place some women at higher risk include if they have had polycystic ovarian syndrome (PCOS), are above healthy weight range, experienced rapid weight gain during first half of pregnancy, and if they currently taking some antipsychotic or steroid medications.
Despite these risk factors, some women develop gestational diabetes without having any of the above risk factors.
The fastest growing type of diabetes in Australia is gestational diabetes
Gestational diabetes accounts for 2.5% of all diabetes in Australia. In 2020, the number of Australian women with gestational diabetes was more than 42,000, including 2,600 South Australian women. Over the past decade, the number of women diagnosed with gestational diabetes has doubled.
There are several reasons for the rapid growth in gestational diabetes, including the age and pre-pregnancy weight of the woman, pregnancy weight-gain, and ethnicity.
All pregnant women get tested for gestational diabetes between 24-28 weeks of pregnancy using an oral glucose tolerance test (OGTT); testing can be done earlier if a mother has additional risk factors for gestational diabetes.
The OGTT involves the mother fasting from food for at least 8 hours. A fasting blood test is taken, then a glucose drink is consumed over 10-15minutes following which another blood sample is taken at 1 and 2 hours after the drink. Depending on the blood glucose levels at fasting, 1 hour and 2 hours, gestational diabetes may be diagnosed. Women with gestational diabetes will need a post-natal follow-up with another OGTT at 6-8 weeks.
Screening and diagnosing gestational diabetes is important. Well managed gestational diabetes can prevent or reduce the short and long-term complications for both mother and baby.
34% of women with gestational diabetes require insulin therapy
Management of gestational diabetes includes a healthy eating plan, regular physical activity, monitoring blood glucose levels, and potentially medication. When blood glucose levels are above the target range medication may be prescribed. This may be oral medication (Metformin), or injectable medication (insulin).
Insulin injections do not harm the baby because insulin does not cross the placenta. Due to changes in the pregnancy hormones, insulin dosage may change during pregnancy. There may be feelings of anxiety, worry, or fear regarding insulin therapy to manage gestational diabetes. It is essential to discuss these with your GP and diabetes educator.
Gestational diabetes generally resolves after the baby's birth, and the need for medication to manage blood glucose levels can stop. Follow-up with a GP 6-8 weeks post-pregnancy is required to determine if gestational diabetes has resolved, or ongoing medical management is needed.
The type of management used is not a reflection of the mother's efforts in managing her blood glucose levels, or her health before pregnancy. Every woman's management of her gestational diabetes will be different.
Gestational diabetes increases the risk of complications during pregnancy and labour for both mother and baby
Women with gestational diabetes are more likely to experience short-term complications during pregnancy and birth. Short-term complications may include high blood pressure, caesarean delivery, trauma due to birthing a larger baby, and anxiety and depression during and after pregnancy. This results in longer hospital admissions pre- and post-pregnancy compared to women without gestational diabetes.
For the baby, short-term complications are more likely; these include premature birth, larger baby, low blood glucose levels in the baby after delivery, and respiratory distress syndrome. Babies born to women with gestational diabetes are more likely to require specialist care following delivery and have longer hospital stays.
The complications associated with gestational diabetes may be prevented with appropriate pre-natal and post-pregnancy care. A team including a credentialled diabetes educator, accredited practicing dietitian, obstetrician, midwife, endocrinologist, and a GP, will work with the mother to manage blood glucose levels within a target range.
Up to 60% of women who have had gestational diabetes will develop type 2 diabetes within 20 years
Women who have had gestational diabetes are at greater risk of developing type 2 diabetes or prediabetes in the future. For women who have had gestational diabetes, regular and ongoing follow-up is important to screen for type 2 diabetes. A follow-up with your GP 6-8 weeks post-pregnancy will check to see if gestational diabetes has resolved. Regular diabetes checks are recommended every 1-3 years, depending on diabetes risk factors.
Women who have had gestational diabetes are also at increased risk of developing cardiovascular disease. There is also an increased risk of childhood obesity, cardiovascular disease, and type 2 diabetes later in life for the baby.
Type 2 diabetes is no longer a condition of 'adulthood', with rates increasing among children and teenagers. A healthy lifestyle can reduce the long-term complications of gestational diabetes for the mother, the baby, and the child. This includes eating a variety of nutritious foods, being active each day, maintaining a healthy weight, limiting alcohol and highly processed foods, quitting smoking, sleeping well, and stressing less.
Regular check-ups with your GP are key to maintaining good health.