Pregnancy is a time of promise and expectation, but it can also raise the possibility for some women that they will develop gestational diabetes mellitus (GDM).
GDM, like other forms of diabetes, is defined as glucose intolerance, but with its first onset during pregnancy. Approximately 3.5% of non-Aboriginal women, and up to 18% of Aboriginal women will develop GDM.
Risk factors for developing this condition include:
• a previous diagnosis of GDM
• age over 35 years
• a history of polycystic ovary syndrome
• hirsutism (excessive body and facial hair)
• acanthosis nigricans (a skin disorder characterized by the appearance of darkened patches of skin)
• being a member of a population considered to be at high risk for diabetes, including women of Aboriginal, Hispanic, South Asian, Asian or African descent.
Although some are at greater risk than others, the Canadian Diabetes Association 2003 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada recommend that all women be screened for GDM between 24 and 28 weeks' gestation using a glucose tolerance test*. For women with multiple risk factors, this testing should be done during the first trimester, then again during the second and third trimesters, even if the first test is negative.
Prompt diagnosis of GDM is important, as it carries several risks to both mother and infant. For example, children born to mothers with GDM may be “macrosomic”, a medical term meaning “severely obese.” This poses a risk of trauma to both mother and baby during the delivery. Macrosomic babies have a higher risk of hypoglycemia after birth – a dangerously low blood glucose level – as well as severe breathing problems. They are also at higher risk for potential long-term obesity and glucose intolerance.
Although the diagnosis should be taken seriously, GDM can be managed by some of the same measures with which type 2 diabetes is managed.
The first step is to make lifestyle changes that can prevent or reverse both GDM and type 2 diabetes. These measures include nutritional therapy – which is best accomplished with the help of a dietitian – to achieve what's called euglycemia, or blood glucose balance. It's important to ensure appropriate weight gain, but not weight loss, and adequate nutritional intake for both mother and baby. Exercise is encouraged, with the frequency and intensity of activity decided with your doctor based on your risk.
If reductions in blood glucose do not reach the recommended levels within two weeks with lifestyle changes, then certain types of insulin can be safely used in pregnancy.
Generally, glucose levels in women who have had GDM return to normal. However, these women do face an increased risk of developing type 2 diabetes later in life, so after the baby is delivered, a follow-up blood glucose test should be done within six months. To reduce the risk of developing diabetes in the future, women should be encouraged to:
Breastfeed. Breastfeeding been shown to reduce the risk for subsequent diabetes in the baby.
• Follow a healthy lifestyle.
• Be screened regularly for the development of type 2 diabetes, or impaired glucose tolerance, also known as “prediabetes”.
• Consult their physician when planning their next pregnancy to check blood glucose levels, and consider taking a folic acid supplement to ensure the best outcomes.
With prompt diagnosis and good management, women with GDM can expect to have a healthy pregnancy and a happy, healthy baby.