Gestational diabetes mellitus (GDM) affects approximately 9.6 to 13.6 per cent of all pregnancies in Australia.1 In most cases, GDM is often asymptomatic; therefore, all pregnant women not known to have pre-pregnancy diabetes or hyperglycaemia in pregnancy should have an oral glucose tolerance test (OGTT) at 24–28 weeks gestation.2 Once GDM is diagnosed, a multidisciplinary team approach is important to reduce the risk of complications during pregnancy, at birth and reduce negative health outcomes for the infant as they mature. Ideally, a team consisting of an obstetrician, endocrinologist, GP, diabetes educator, midwife and dietitian is required to manage GDM. As part of the multidisciplinary team, dietitians play an important role, as lifestyle management is the cornerstone of management of GDM.
Dietitians use a toolbox of knowledge, skills and nutrition counselling techniques to assist women with making dietary and lifestyle modifications. Effective nutrition interventions can assist in normalising blood glucose levels to prevent or delay the need for medication, maximise nutrition to support the development of the fetus and minimise complications throughout the pregnancy and during delivery.
When first diagnosed with GDM, if referred, women receive education from a dietitian in a group or individual setting. Education is tailored to the individual needs, taking into account personal and cultural beliefs, food preferences, lifestyle, and willingness and ability to change behaviours.
Dietary requirements for those with GDM are the same for all pregnant women; however, emphasis is placed on the importance of regular meals and snacks, the role of carbohydrate foods, frequency, timing and quantity of carbohydrates consumed, and the glycaemic index of food. Dietitians also consider appropriate weight gain depending on the woman’s pre-pregnancy BMI. During pregnancy, too much weight gain can contribute to high blood pressure and increase insulin resistance. Strict dieting is not usually recommended, as it is important for women to have a balanced diet to meet their nutritional requirements for pregnancy.
Dietitians consider a range of individual nutrition factors when reviewing women with gestational diabetes, including meal frequency or regularity, pre-pregnancy eating habits (for example, binging or fasting for long periods), religious or cultural beliefs with foods, allergies or intolerance, and quality and quantity of foods consumed at meal or snack times. It is also important to take into account appropriate portions of macronutrients and micronutrients based on the Australian Guide to Healthy Eating core food groups during pregnancy and the Nutrient Reference Values (NRVs), to help maximise nutrition for both mother and baby.
Challenges can arise when treating women with GDM, including access to resources and funding for timely follow-up; literacy levels of women; access to culturally appropriate resources and interpreter services; access to a multidisciplinary team; and patient compliance and adherence to nutrition recommendations.
It is important for the multidisciplinary team to be aware that a number of pregnant women with GDM try to restrict their carbohydrate intake to facilitate a reduction in postprandial blood glucose levels. This can increase risk of nutritional inadequacies and/or result in hypoglycemia for women on insulin.
Ideally, women with GDM should receive regular follow up from a dietitian throughout their pregnancy to review their nutritional progress, compliance with recommendations, blood glucose levels and implementation of physical activity to promote optimal blood glucose control. If diet and lifestyle interventions are not effective, dietitians can assist in identifying the need for the use of medication.
Women with GDM should have a follow-up OGTT, preferably at six to 12 weeks postpartum, to ensure there is no underlying type 2 diabetes mellitus.2 Women diagnosed with hyperglycaemia during pregnancy should also be monitored as they have a 30 per cent risk of recurrence in a subsequent pregnancy and a risk of developing type 2 diabetes, ranging from 1.5 to ten per cent per year. Women contemplating another pregnancy should have an annual OGTT. Women tested for possible development of type 2 diabetes should have an OGTT or HbA1c every three years, or more frequently, depending on clinical circumstances. For women considered low-risk, a fasting plasma glucose test or HbA1c every one to two years should be sufficient.3
Breastfeeding has a number of benefits for both mother and baby, including weight reduction for mothers. Breastfeeding should be supported and encouraged postpartum.4
In summary, it is important that every woman diagnosed with gestational diabetes is referred to a dietitian for assessment and education during her pregnancy.