Terms explained

BMI

BMI, or body mass index, is a measure of a person's weight in relation to their height. A person with BMI of 25 kg/m2 or over is overweight, and a person with a BMI of 30 kg/m2 or over is classed as obese.

Booking appointment

Your first official antenatal appointment. It normally takes place between 8 and 10 weeks of pregnancy, and you 'book in' for maternity care with a midwife and/or your GP. It may be earlier if you have diabetes before getting pregnant.

Diabetic ketoacidosis (DKA)

High blood glucose (hyperglycaemia) that is not treated can lead to a serious condition called DKA. People with type 1 diabetes are more at risk of DKA, but anyone with diabetes can get it. It is caused by the build‑up of harmful ketones in the blood. People with DKA need to be treated in hospital as an emergency.

Diabetic nephropathy

People with diabetes are at risk of kidney disease, known as diabetic nephropathy. Diabetes can damage the small blood vessels in the kidneys and stop them from working properly. The earliest sign is having a protein called albumin in the urine. Women with nephropathy are at high risk of developing high blood pressure in pregnancy (called pre‑eclampsia).

Diabetic retinopathy

People with diabetes are at risk of having eye problems, called diabetic retinopathy. Diabetes can damage the small blood vessels around the retina (the seeing part of the eye), which can cause blurred vision. The early stages of retinopathy do not cause symptoms, so it is very important to have regular checks which can detect any changes.

Family origin

Your ethnic background. Some women have an increased risk of gestational diabetes because of their ethnicity, including (but not only) women with a South Asian, African–Caribbean or Middle Eastern family origin.

Fasting plasma glucose test

A blood test to check fasting (usually before breakfast) blood glucose levels. As well as being used to diagnose diabetes, the test can show whether there are problems in the way the body is using glucose.

Glibenclamide

A medicine (tablet) for treating type 2 diabetes and gestational diabetes. Glibenclamide helps the body to produce more insulin. Because of this, it can cause hypoglycaemia. At the time of publication, glibenclamide may be recommended for 'off-label' use in this guideline. Your doctor should tell you this and explain what it means for you.

Glucagon

A hormone that raises blood glucose levels. It can be given as an injection in emergencies to people with diabetes who have hypoglycaemia.

HbA1c test

A blood test that measures the average blood glucose level over the previous 2 to 3 months. The result is usually given in mmol/mol (it used to be given as a percentage). In people without diabetes, it is usually below 42 mmol/mol (or 6%). An HbA1c test is a less precise measure of blood glucose levels after about 12 weeks of pregnancy.

Hyperglycaemia

A higher than normal level of glucose in the blood. Symptoms include feeling thirsty and hungry, and increased urination. If it is not treated, hyperglycaemia can lead to diabetic ketoacidosis.

Hypoglycaemia or a hypo

A lower than normal level of glucose in the blood – usually less than 4 mmol/litre. The symptoms of a hypo include feeling dizzy (or even losing consciousness), feeling tired, feeling hungry, shaking and sweating. It is important to recognise the warning signs of a hypo. You are at risk of hypoglycaemia if you are on insulin or glibenclamide, but not otherwise.

Ketones

Harmful ketones in the blood are produced when the body starts to use its fat stores to make energy. It normally only does this during starvation or if the body doesn't have enough insulin. High levels of ketones can lead to diabetic ketoacidosis. Blood ketone testing strips are the easiest way to check for ketones.

Metformin

A medicine (tablet) that lowers blood glucose levels in people with diabetes. Because of the way it works, metformin does not increase insulin levels, and does not cause hypoglycaemia unless you are also on insulin or glibenclamide. At the time of publication, metformin may be recommended for 'off-label' use in this guideline. Your doctor should tell you this and explain what it means for you.

Neonatal hypoglycaemia

A lower than normal blood glucose level in a newborn baby ('neonate'), defined as below 2 mmol/litre. There is a risk of neonatal hypoglycaemia in babies born to mothers with diabetes, particularly if the woman is taking insulin or glibenclamide.

'Off-label' use

In the UK, medicines are licensed to show that they work well enough and are safe enough to be used for specific conditions and groups of people. Some medicines can also be helpful for conditions or people they do not have a licence for (such as pregnant women). This is called 'off‑label' use. Off‑label use might also mean the medicine is taken at a different dose or in a different way to the licence, such as using a cream or taking a tablet. There is more information about licensing medicines on NHS Choices.

Oral glucose tolerance test (OGTT)

An OGTT uses 2 blood samples: the first to check fasting (usually before breakfast) blood glucose levels, and the second to check levels again 2 hours after a glucose drink. This is the usual test for diagnosing gestational diabetes.

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