Normal blood sugar range for gestational diabetes

You’ll need to get your blood sugar tested to find out for sure if you have prediabetes or type 1, type 2, or gestational diabetes. Testing is simple, and results are usually available quickly.

Tests for Type 1 Diabetes, Type 2 Diabetes, and Prediabetes

Your doctor will have you take one or more of the following blood tests to confirm the diagnosis:

A1C Test

The A1C test measures your average blood sugar level over the past 2 or 3 months. An A1C below 5.7% is normal, between 5.7 and 6.4% indicates you have prediabetes, and 6.5% or higher indicates you have diabetes.

Fasting Blood Sugar Test

This measures your blood sugar after an overnight fast (not eating). A fasting blood sugar level of 99 mg/dL or lower is normal, 100 to 125 mg/dL indicates you have prediabetes, and 126 mg/dL or higher indicates you have diabetes.

Glucose Tolerance Test

This measures your blood sugar before and after you drink a liquid that contains glucose. You’ll fast (not eat) overnight before the test and have your blood drawn to determine your fasting blood sugar level. Then you’ll drink the liquid and have your blood sugar level checked 1 hour, 2 hours, and possibly 3 hours afterward. At 2 hours, a blood sugar level of 140 mg/dL or lower is considered normal, 140 to 199 mg/dL indicates you have prediabetes, and 200 mg/dL or higher indicates you have diabetes.

Random Blood Sugar Test

This measures your blood sugar at the time you’re tested. You can take this test at any time and don’t need to fast (not eat) first. A blood sugar level of 200 mg/dL or higher indicates you have diabetes.

*Results for gestational diabetes can differ. Ask your health care provider what your results mean if you’re being tested for gestational diabetes.
Source: American Diabetes Association

If your doctor thinks you have type 1 diabetes, your blood may also tested for autoantibodies (substances that indicate your body is attacking itself) that are often present in type 1 diabetes but not in type 2 diabetes. You may have your urine tested for ketones (produced when your body burns fat for energy), which also indicate type 1 diabetes instead of type 2 diabetes.

Tests for Gestational Diabetes

Gestational diabetes is diagnosed using blood tests. You’ll probably be tested between 24 and 28 weeks of pregnancy. If your risk is higher for getting gestational diabetes (due to having more risk factors), your doctor may test you earlier. Blood sugar that’s higher than normal early in your pregnancy may indicate you have type 1 or type 2 diabetes rather than gestational diabetes.

Glucose Screening Test

This measures your blood sugar at the time you’re tested. You’ll drink a liquid that contains glucose, and then 1 hour later your blood will be drawn to check your blood sugar level. A normal result is 140 mg/dL or lower. If your level is higher than 140 mg/dL, you’ll need to take a glucose tolerance test.

Glucose Tolerance Test

This measures your blood sugar before and after you drink a liquid that contains glucose. You’ll fast (not eat) overnight before the test and have your blood drawn to determine your fasting blood sugar level. Then you’ll drink the liquid and have your blood sugar level checked 1 hour, 2 hours, and possibly 3 hours afterward. Results can differ depending on the size of the glucose drink and how often your blood sugar is tested. Ask your doctor what your test results mean.

Prevent Type 2 Diabetes

If your test results show you have prediabetes, ask your doctor or nurse if there is a lifestyle change program offered through the CDC-led National Diabetes Prevention Program in your community. You can also search for an online or in-person program. Having prediabetes puts you at greater risk for developing type 2 diabetes, but participating in the program can lower your risk by as much as 58% (71% if you’re over age 60).

Diabetes Treatment Plan

If your test results show you have type 1, type 2, or gestational diabetes, talk with your doctor or nurse about a detailed treatment plan—including diabetes self-management education and support services—and specific steps you can take to be your healthiest.

To monitor your glucose, you will be given a blood glucose monitor. This is designed for you to measure your own blood glucose levels at home, or wherever you happen to be, by checking a drop of your blood. You produce the blood by using a finger pricker.

There are many different brands of meter on the market, but they all work in similar ways:

Step 1  Wash your hands.

Step 2  Set up a finger pricker with a clean needle.

Step 3  Insert one end of a test strip (usually a long, thin paper-type strip) into the meter.

Step 4  Use the finger pricker to prick the side of your finger.

Step 5  When a spot of blood appears where you pricked you finger, place it onto the end of the testing strip that is sticking out of the meter to transfer the blood.

Step 6  After a few seconds, the meter will display your blood glucose level.

Step 7  Clean the blood off your finger.

Step 8  Record the results in your blood glucose diary or diabetes journal, or you may have a phone app that you use.

Step 9  Throw away the test strip.

Step 10 Dispose of the needle from the finger pricker safely, by putting it in your sharps bin.

Your blood glucose level is measured in millimoles per litre (mmol/L), but you don’t need to worry about that – just about the numbers.

"The first week when I was recording my blood sugars, the dietician said ‘Once we’ve seen your results, we can go through what you’re doing right and wrong’. It turned out I was eating too much fruit and yoghurt with my lunch." Gemma, mum of one

When should I measure my blood glucose?

Throughout the rest of your pregnancy, you will need to measure your blood glucose levels at various points through the day, to check that they are within the limits you have been given at each of those times:

When you get up  You need to measure your blood glucose levels each morning when you get up, before you have anything to eat or drink. This blood glucose level is called your ‘fasting blood glucose level’ because you will have an empty stomach. You must not have eaten or drunk anything apart from water overnight, for at least eight hours.

Your team should have discussed this with you and agreed the ideal morning blood glucose level for you to aim for. 

Before or after every meal  You will probably be asked to measure your blood glucose level around the time of a meal. Some services measure before eating (‘pre-prandial monitoring’) while others measure one or two hours after a meal (‘postprandial monitoring’).

Again, you will have discussed and agreed an ideal blood glucose level after meals with your diabetes team. These levels will be higher than your fasting blood glucose levels, as you will just have eaten.

If you are taking insulin to help to control your blood glucose levels, you may need to do a separate test before you go to bed, or even during the night, although this is unusual.

"When we did go out for a special meal or two, and I'd have a little bit of cheesecake or something, it really affected my sugar levels. But that would've been just twice in the whole pregnancy." Gemma, mum of one

How do I interpret the results?

Your blood glucose levels tell you if your gestational diabetes is under control.

The blood glucose levels before breakfast and after meals should be within the ideal levels that you have discussed and agreed with your diabetes team. If they are not, you should have been given instructions about what to do next. If you are not sure about this, get in touch with your main point of contact, and ask for their advice.

Read about the risks of low blood glucose (‘hypoglycaemia’) and what to do about it.

You will have contact with your diabetes team every one-to-two weeks through your pregnancy, either by phone or in person. They are there to give you advice and support, including keeping an eye on your blood glucose levels and advising you what to do if they are not at the ideal levels. You may also have a number to call if you have questions in between those times. You can also get support from the Diabetes UK Careline 0345 123 2399 or the Tommy’s midwives on 0800 0147 800.

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