Gestational diabetes

Gestational diabetes is:

• diabetes diagnosed in pregnancy
• a fairly common complication of pregnancy
• usually symptom free (you are unaware)
• diagnosed during routine screening
• becoming more common in women of all ethnicities.

It usually develops after week 24 week of pregnancy but it can happen earlier. If you are diagnosed in early pregnancy, you may have underlying diabetes that has not been recognised before.

Your body gets a lot of its energy from glucose. Glucose is sugar that comes the carbohydrate foods you digest after eating, for example, bread, rice and pasta, some root vegetables, sugary food and drinks.

The glucose then enters your bloodstream from your gut.

Your body uses a hormone called insulin to get glucose to move from the bloodstream to the muscle and other tissues of the body, so it can be used as energy. In pregnancy, your body needs 4 times the normal amount of insulin for this.

Other hormones from your placenta that help your pēpi develop can block the normal action of insulin. This is called insulin resistance and it is a problem. Insulin resistance allows glucose to build up in your blood rather than enter the muscle and other tissues.

You may be at higher risk of gestational diabetes if you:

• are overweight
• have diabetes before pregnancy
• gain too much weight during pregnancy
• have a family history of diabetes
• are over 30 years old
• have had gestational diabetes before
• have had a large baby before
• have had previous pregnancy loss (miscarriage or stillbirth)
• have polycystic ovary syndrome.

Blood sugar levels and pregnancy planning (internal link)

An HbA1c test (a measure of your blood glucose level) is performed with your first blood test in pregnancy or your ‘antenatal bloods’. This can show if you are at risk of developing early gestational diabetes. 

If the HbA1c result is above 40mmol/mol, you will be referred to a diabetes in pregnancy service.

It is recommended all pregnant women are tested for gestational diabetes between weeks 24 and 28 of pregnancy — using the oral glucose challenge (polycose) test and if needed the oral glucose tolerance test.

Diabetes testing in pregnancy (internal link)

The aim is to keep your blood glucose level within the target range. Doing this improves the outcomes for you and your pēpi.

The gestational diabetes team usually has a doctor, obstetrician, diabetes midwife, dietitian, social worker and physiotherapist. They will give you the information, support and professional guidance you need. With this support and your commitment, you can do well with gestational diabetes. 

Meal planning

A dietitian helps you develop a meal plan which works with your lifestyle. This healthy eating plan:

• is low in fat
• has no added sugar
• is high in fibre.

The carbohydrate (glucose-making foods) you eat are evenly spread over the day. This creates smaller rises in blood sugar after meals and makes good use of the insulin you have. The meal plan has plenty of nutritious choices.

It is important you continue to eat a healthy amount of carbohydrates — they are very important for growing your pēpi. The reason for the low-fat eating plan is because fatty food can increase insulin resistance.

Diabetes New Zealand has helpful information on healthy eating with diabetes.

Healthy eating — Diabetes New Zealand (external link)

Exercise

Being physically active helps your body control the level of glucose in your blood by helping insulin to work properly. Aim to do 30 minutes of moderate intensity activity on most days of the week, such as walking, swimming or water walking.

Any exercise is better than none.

Blood testing

You will need to check your blood glucose 4 times a day:

• when you wake up
• 2 hours from the start of eating breakfast, lunch and dinner. 

Blood glucose targets are:

• less than 5.0mmol/L before breakfast
• less than 6.0mmol/L at 2 hours after the start of each meal.

Each result must be recorded so you and the team can see the patterns and work out the best way for you to manage your gestational diabetes.

If your blood glucose level is higher than the target, note the last meal you ate and talk about it with your gestational diabetes team.

Medicines

In some pregnancies, diet and exercise are not enough to achieve target blood glucose levels. To reach the target, tablets such as metformin or insulin injections can provide the help needed. 

Your gestational diabetes team will talk with you regularly about your blood glucose results and adjust your plans. Diabetes management is stopped when you are in active labour and is not needed after the birth of your pēpi.

Gestational diabetes, pregnancy and your baby (internal link)