Gestational Diabetes Blood Sugar Levels

The NICE numbers, quoted rather than paraphrased

These are the targets used across the UK, and they are the same for gestational diabetes and pre-existing diabetes. NICE guideline NG3 recommendation 1.2.12 says to "use the same capillary plasma glucose target levels for women with gestational diabetes as for women with pre-existing diabetes".

NICE NG3, recommendation 1.3.5: "Advise pregnant women with any form of diabetes to maintain their capillary plasma glucose below the following target levels, if these are achievable without causing problematic hypoglycaemia:

• fasting: 5.3 mmol/litre and
• 1 hour after meals: 7.8 mmol/litre or
• 2 hours after meals: 6.4 mmol/litre."

NICE NG3, recommendation 1.3.6: "Advise pregnant women with diabetes who are taking insulin to maintain their capillary plasma glucose level above 4 mmol/litre."

Two details in that wording get lost in most summaries. The one-hour and two-hour targets are joined by "or", not "and" — you test at one point after a meal, not both. And the whole recommendation is conditional on being achievable "without causing problematic hypoglycaemia", which is why recommendation 1.3.4 asks teams to "agree individualised targets for self-monitoring of blood glucose with pregnant women with diabetes, taking into account the risk of hypoglycaemia". If your team has set you slightly different numbers, that is the guideline working, not a mistake.

Diabetes Canada's figures, named separately

Targets are not international. Diabetes Canada's clinical practice guidelines state that for women with gestational diabetes, "good outcomes have been reported using targets of FBG less than 5.3 mmol/L, 1 hour postprandial BG less than 7.8 mmol/L and 2 hours postprandial less than 6.7 mmol/L".

The fasting and one-hour figures match NICE. The two-hour figure does not: 6.7 mmol/litre in Canada against 6.4 mmol/litre under NICE. That is a small difference with a real consequence, because a reading of 6.5 mmol/L at two hours is over target in the UK and inside target in Canada.

Diabetes Canada also notes that women receiving insulin "should maintain BG greater than 3.7 mmol/L to avoid repeated hypoglycaemia", where NICE sets the floor at 4 mmol/litre.

We are not reproducing the American Diabetes Association's figures here. Their standards of care sit behind a paywall we could not read, and quoting numbers second-hand is exactly how wrong thresholds spread. ACOG's public patient information describes how to track blood sugar and how often to test but does not publish numeric targets on that page. If your care is in the United States, ask your obstetrician for the figures your practice uses in writing rather than taking them from a website.

How often you are asked to test

NICE NG3 recommendation 1.3.3: "Advise pregnant women with type 2 diabetes or gestational diabetes to test their fasting and 1-hour post-meal blood glucose levels daily if they are: managing their diabetes with diet and exercise changes alone or taking oral therapy (with or without diet and exercise changes) or single-dose intermediate-acting or long-acting insulin."

Recommendation 1.2.11 puts the teaching obligation on the service: "Teach women with gestational diabetes how to self-monitor their blood glucose." Meters, strips and lancets are provided by the NHS for this; you should not be buying them.

What a single high reading means

Less than the number itself suggests. One raised reading after an unusual meal, an illness, a bad night's sleep or a steroid injection is not the same as a pattern. The clinic is looking at how many of your readings sit above target across a week and at which time of day they cluster.

Where the numbers do have hard consequences is at diagnosis, and the thresholds there are specific. NG3 recommendation 1.2.18 offers a trial of diet and exercise where the fasting plasma glucose at diagnosis is "below 7 mmol/litre". Recommendation 1.2.22 offers immediate insulin, with or without metformin, where it is "7.0 mmol/litre or above". Recommendation 1.2.23 says to consider immediate insulin where it is "between 6.0 and 6.9 mmol/litre" and there are complications such as macrosomia or hydramnios.

After the trial starts, recommendation 1.2.19 is time-limited: "If blood glucose targets are not met with diet and exercise changes within 1 to 2 weeks, offer metformin." Metformin and insulin are the named treatments; doses are set by your team and are not published here.

Units, and why an online figure may look wrong

The UK, Ireland, Canada, Australia and New Zealand report blood glucose in millimoles per litre. The United States reports in milligrams per decilitre. A figure that looks impossibly high or low next to your meter is usually a units problem rather than a disagreement.

Check which unit a source uses before comparing anything to your own readings, and check that your meter is set to mmol/L if you are being cared for in the UK or Ireland.

What the readings are actually for

The point of the numbers is not the numbers. NG3 recommendation 1.2.10 says teams should explain "that good blood glucose control throughout pregnancy will reduce the risk of fetal macrosomia, trauma during birth (for her and her baby), induction of labour and/or caesarean section, neonatal hypoglycaemia, and perinatal death".

Your readings also drive the rest of your care. NG3 recommendation 1.3.34 offers ultrasound monitoring of fetal growth and amniotic fluid volume every four weeks from 28 to 36 weeks, and recommendation 1.3.38 expects contact with the joint diabetes and antenatal clinic every one to two weeks throughout pregnancy. Bring the log to every appointment; it is the single most useful thing you carry.