What is gestational diabetes?

Many are familiar with the term and meaning of diabetes, due to its increasing prevalence worldwide, however the term gestational diabetes, and why this occurs, perhaps less so. Gestational diabetes mellitus (GDM) is a type of diabetes that first occurs during pregnancy, whereby your blood sugar levels are out of the usual range, which can have serious health implications for both you and your baby. It affects around 12-14% of women, and usually develops during the 24-28^th week during pregnancy, and is tested for using an OGTT (oral glucose tolerance test). [1]

So what actually causes GDM?

When sugar (glucose) is absorbed into the bloodstream after you eat a meal, a hormone produced by the pancreas called insulin is released, which takes the glucose from your bloodstream into your cells so they can use this as energy. During pregnancy, your body is required to make 2-3 times more insulin than it usually would. This is due to the fact that that your placenta is producing hormones that prevent the insulin from working as it should to take the glucose out of your bloodstream. If your body cannot produce/respond to the extra insulin required, you can develop GDM. [1]

Who is at risk of developing gestational diabetes?

If you are/have one or more of the following you have an increased risk of developing GDM:

·     Hyperglycaemia during a past pregnancy

·     Elevated blood glucose levels prior to pregnancy

·     ≥40 years of age

·     Asian, Aboriginal or Torres Strait Islander, Maori, Middle Eastern, Indian subcontinent, Pacific Islander or non-white African

·     A family history of diabetes (this is a 1^st degree relative or a sister with/who has had hyperglycaemia during pregnancy)

·     BMI >30 prior to pregnancy

·     Macrosomia (a previous baby >4.5kg or >90^th centile)

·     Polycystic ovarian syndrome (PCOS)

·     Taking corticosteroid or antipsychotic medication [2]

What are some of the risks of GDM to you and your baby?

·     Macrosomia (baby)

·     Miscarriage

·     Increased risk of developing Type 2 diabetes later in life (mother) [3]

Diet:

The 3 main macronutrients are protein, fat and carbohydrate. The main nutrient effecting blood glucose levels are carbohydrates. Carbohydrates are not just breads and pastas, but also other grains such as rice and cereals, as well as fruit, starchy vegetables, milk and yoghurt, and foods that are commonly thought of like biscuits, cakes, sugar, chocolate, lollies, soft drink and ice-cream. It is important to stress the fact that carbohydrates are a very important energy source, especially when you are pregnant. The literature states that <175g of carbohydrates is inappropriate and therefore should not be restricted below this level. [4]

There are 2 main things to take away from this article; it is the TYPE and AMOUNT of carbohydrate that are important in maintaining blood glucose levels within a normal range.

TYPE:

This is where the glycaemic index or GI of the food is important. GI is a relative ranking of how the carbohydrate in a particular food affects blood glucose level. It relates to how quickly the food is digested, absorbed and metabolised so that it can change blood glucose levels. [5] Foods classified as low GI partake in these processes at a slower rate and cause a more gradual rise in blood glucose levels over a longer period of time, allowing insulin more time to act to bring the glucose into cells and lower the level of glucose in the blood.

AMOUNT:

To maintain energy throughout the day carbohydrate containing foods must be spread relatively evenly to keep blood glucose levels within range. It is recommended that 2-3 carbohydrate servings (called exchanges) are consumed at breakfast, lunch and dinner, and 1-2 exchanges at morning,  afternoon tea and supper. [6] But what exactly is an exchange of carbohydrate? An exchange of carbohydrate is considered to be about 15g worth of carbohydrate. Below is a list of foods containing this amount. Therefore, if 3 exchanges of carbohydrate are consumed at breakfast, this could include a banana and 2 slices of toast. Which would equate to approximately 45g of carbohydrate (15g x 3).