High fasting levels in gestational diabetes

High fasting blood sugar levels are one of the most common challenges faced by people with gestational diabetes.

Fasting levels are the blood sugar readings taken first thing in the morning, before eating or drinking anything (other than water).

For many people, fasting levels are the hardest readings to control. Unlike post-meal blood sugar levels, which are heavily influenced by what we eat and drink, fasting levels are affected by a combination of factors, including pregnancy hormones, insulin resistance, sleep, hydration, activity levels, and overnight glucose production by the liver​.​

This means that you can be following your meal plan carefully, staying active, and still experience fasting readings above your target range.

If you’re struggling with high fasting levels, you’re not alone. It is one of the most common concerns raised within the Gestational Diabetes UK support community and is often the reason that medication such as Metformin or insulin may be recommended.

The good news is that there are several strategies that may help improve fasting blood sugar levels, although it is important to remember that what works for one person may not work for another.

The sections below explain each of these factors in more detail and why fasting levels can be particularly difficult to control during pregnancy.

Following this we will go on to explain tips that may help reduce high fasting levels in gestational diabetes.

Newly Diagnosed with Gestational Diabetes?

Struggling with fasting blood sugar levels is one of the most common concerns we hear about. If you’ve recently been diagnosed, our free guide can help you understand gestational diabetes and feel more confident managing your blood sugar levels.

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Your First Week with Gestational Diabetes

Inside you’ll find:

✓ What gestational diabetes is and why it happens

✓ Blood sugar targets explained

✓ What to eat and what not to cut out

✓ Tips for testing and managing your levels

✓ Reassurance and practical advice for the days ahead

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What Can Affect Fasting Blood Sugar Levels?

Fasting blood sugar levels are influenced by far more than just what you eat before bed.

Unlike post-meal blood sugar readings, which are largely affected by food choices, fasting levels are influenced by a combination of factors, including pregnancy hormones, insulin resistance, hydration, sleep quality, activity levels, and the timing and composition of your evening meal.

This is one of the reasons fasting levels can feel so frustrating. You may be following your meal plan carefully and still wake up to a reading above your target range.

The factors below are some of the most common things that may affect fasting blood sugar levels.

Your Evening Meal

The amount and type of carbohydrate eaten in the evening can influence fasting blood sugar levels the following morning.

Eating a large amount of carbohydrate at dinner may leave your body working harder overnight to process the glucose released into the bloodstream. Likewise, very high-fat meals, such as takeaways or fast food, can slow digestion and may cause blood sugar levels to remain elevated for longer.

This doesn’t mean you should avoid carbohydrates altogether. Carbohydrates are an important source of energy during pregnancy, and restricting them too much may increase the risk of ketones developing.

Instead, aim for a balanced evening meal that combines:

• A sensible portion of carbohydrate

• Protein

• Natural fats

• Plenty of non-starchy vegetables or salad

Everyone responds differently, so it can be helpful to review your blood sugar results and look for patterns over several days rather than focusing on a single reading.

Meal Timing

For some people, the timing of their evening meal or bedtime snack may influence fasting blood sugar levels the following morning.

Going for a very long period without eating overnight can sometimes result in higher fasting levels. Likewise, eating a large meal immediately before bed may not give your body enough time to process the glucose before you go to sleep.

This is one reason why some people find that a bedtime snack helps improve fasting levels. The goal is not to eat a large meal before bed, but rather a small snack that may help provide a steadier supply of energy overnight.

Many members of our support group report the best results from snacks that combine protein and natural fats.

Finding what works for you may take some trial and error. A bedtime snack does not improve fasting levels for everyone, and some people may even find their fasting readings are higher after eating one.

As pregnancy progresses and insulin resistance increases, you may find that a snack that worked well earlier in pregnancy becomes less effective later on.

The most important thing is to look for patterns in your own blood sugar readings and discuss any concerns with your diabetes team.

Hydration

Staying well hydrated is important when managing gestational diabetes.

Dehydration can contribute to higher blood sugar levels because there is less fluid available to help transport glucose around the body and support normal kidney function.

Pregnancy can increase your fluid requirements, and factors such as hot weather, sickness, exercise, or simply forgetting to drink enough can make dehydration more likely.

Try to drink regularly throughout the day rather than waiting until you feel thirsty. Some people also find it helpful to keep a glass or bottle of water by the bed, particularly if they wake during the night.

While improving hydration alone may not solve high fasting levels, it is a simple change that may support overall blood sugar management and wellbeing.

Sleep Quality

Poor sleep and shorter sleep duration have been associated with higher blood sugar levels in pregnancy​​.​

Unfortunately, getting a good night’s sleep isn’t always easy during pregnancy. Frequent trips to the bathroom, discomfort, reflux, leg cramps, anxiety, and pregnancy hormones can all disrupt sleep.

Research has shown that poor sleep quality may affect the way the body responds to insulin, potentially making blood sugar levels more difficult to manage.

While improving sleep won’t necessarily solve high fasting levels, prioritising good sleep habits may support overall blood sugar management and wellbeing.

If possible, try to:

• Maintain a regular sleep routine

• Avoid caffeine later in the day

• Keep your bedroom cool and comfortable

• Use pillows to support a comfortable sleeping position

• Rest when you can

Remember that poor sleep is common during pregnancy, and struggling with fasting levels does not mean you are doing anything wrong.

Many people assume that high fasting levels are caused entirely by what they ate the night before. While food choices, meal timing, hydration and sleep can all play a role, fasting levels are also heavily influenced by hormones and insulin resistance.

Two commonly discussed explanations for high fasting levels are the Dawn Phenomenon and the Somogyi Effect.

The Dawn Phenomenon

The Dawn Phenomenon is a natural rise in blood sugar levels that occurs in the early hours of the morning​.​

During the night, the body releases hormones such as cortisol, growth hormone, glucagon and adrenaline to help prepare us to wake up and start the day. These hormones signal the liver to release stored glucose into the bloodstream, providing the body with a source of energy.

This process happens in everyone, whether they have diabetes or not.

In people without diabetes, the body produces enough insulin to keep blood sugar levels stable. However, in people with gestational diabetes, increasing insulin resistance can make it harder for the body to process this extra glucose effectively.

As a result, blood sugar levels may rise during the early hours of the morning, leading to higher fasting readings when you wake up.

The Dawn Phenomenon is one reason why fasting levels can be particularly difficult to control and why some people continue to experience high fasting readings despite making changes to their diet, activity levels and bedtime routine.

This increase in blood sugar levels typically occurs between approximately 3 am and 8 am, although the exact timing varies from person to person.

Remember: The Dawn Phenomenon is driven by hormones and insulin resistance, not simply by what you ate the night before. This is one reason why fasting levels can be much harder to control than post-meal blood sugar levels.

While other theories, such as the Somogyi Effect, have been proposed to explain high fasting blood sugar levels, the Dawn Phenomenon and increasing insulin resistance are generally considered more likely explanations for elevated fasting readings during pregnancy.

Practical Ways to Help Lower Fasting Blood Sugar Levels

There is no single solution that works for everyone when it comes to fasting blood sugar levels.

Because fasting levels are influenced by pregnancy hormones, insulin resistance, sleep, hydration, activity levels and food choices, finding what works for you may involve some trial and error.

Some people notice improvements with small changes to their evening routine, while others may require medication or insulin to achieve fasting levels within their target range.

The following strategies may help improve fasting blood sugar levels, although results vary from person to person.

The infographic above highlights some of the most commonly used strategies that may help improve fasting blood sugar levels. Some people notice improvements with small changes such as a bedtime snack, increased hydration, or a short walk after dinner, while others may require medication or insulin to achieve fasting levels within their target range.

Activity After Dinner

Physical activity has an insulin-like effect on the body’s cells and may help lower blood sugar levels.

Many people find that a short walk after their evening meal helps improve their fasting readings the following morning.

This doesn’t need to be intense exercise. Gentle movement, such as walking, swimming, housework, or pregnancy-safe exercise, can all be beneficial.

If you are able to be active after dinner, even 10–20 minutes of movement may help support blood sugar management overnight.

Bedtime Snacks

One of the most commonly discussed strategies for improving fasting blood sugar levels is having a bedtime snack.

Many members of the Gestational Diabetes UK support community report that a small bedtime snack helps improve their fasting readings, although it is important to remember that this does not work for everyone.

The aim is not to eat a large meal before bed, but rather a small snack that may help provide a steadier supply of energy overnight.

What Makes a Good Bedtime Snack?

Many people find that snacks containing protein and natural fats work best, as these tend to have less impact on blood sugar levels and may help keep you feeling satisfied overnight.

Examples include:

• Ham and cheese roll-ups

• A boiled egg

• Cheese and oatcakes

• Cheese and wholegrain crackers

• Peanut butter on wholemeal toast

• Avocado on wholemeal crackers

• Greek yoghurt and a few berries

• Cottage cheese

• A handful of mixed nuts

• Apple slices with peanut butter

• Celery sticks with cream cheese

• Hummus with vegetable sticks

• A small glass of milk

• A small glass of milk with a GD UK brownie

• A sugar-free hot chocolate with cream

• A Babybel and a few wholegrain crackers

• A small portion of leftovers containing protein

Finding what works best for you may take some trial and error. A snack that helps one person may have little effect for someone else.

It is also common for a snack that worked well earlier in pregnancy to become less effective as insulin resistance increases later in pregnancy.

While bedtime snacks can be helpful for some people, they are not a cure for high fasting levels. If you do not notice any improvement after trying different options, this does not mean you are doing anything wrong.

Apple Cider Vinegar

Some people choose to try apple cider vinegar before bed to see whether it helps improve their fasting blood sugar levels.

A small study in people with type 2 diabetes found that consuming 2 tablespoons of apple cider vinegar with a small amount of cheese before bed resulted in modest improvements in fasting blood sugar levels the following morning​.

Although evidence in gestational diabetes is limited, some members of the Gestational Diabetes UK support community report that it has helped lower their fasting readings.

If you would like to try apple cider vinegar, a common approach is:

• 2 tablespoons of apple cider vinegar

• Diluted in a glass of water

• Taken before bed

Some people choose to pair this with a protein-based snack such as a small piece of cheese.

As vinegar is acidic, it is important to dilute it before drinking and consider rinsing your mouth with water afterwards to help protect your teeth.

While some people find apple cider vinegar helpful, others notice little or no difference. It should be viewed as one possible strategy rather than a guaranteed solution for high fasting blood sugar levels.

Myo-Inositol

Myo-inositol is a naturally occurring substance found in the body and in foods such as wholegrains, beans, nuts, seeds and some fruits.

It plays an important role in insulin signalling and insulin sensitivity, which is why it has attracted increasing interest in gestational diabetes research.

Over the years, many members of the Gestational Diabetes UK support community have reported improvements in their fasting blood sugar levels after taking myo-inositol supplements. While individual experiences vary, it is one of the supplements most frequently mentioned by those struggling with high fasting readings.

Research into myo-inositol has also grown considerably. Several studies and systematic reviews have found that myo-inositol supplementation may improve insulin sensitivity, reduce fasting blood sugar levels, and lower the likelihood of needing insulin treatment in some people. Some studies have also suggested it may reduce the risk of gestational diabetes developing in higher-risk pregnancies.

The most commonly studied dose is:

• 2g myo-inositol twice daily (4g per day total)

• Often taken alongside folic acid

However, research findings have not been entirely consistent, and myo-inositol is not currently included in routine NHS treatment guidelines for gestational diabetes. Some recent studies have shown less benefit in certain groups, highlighting the need for further research.

If you are considering taking myo-inositol during pregnancy, it is important to discuss this with your diabetes team, midwife or obstetrician first to ensure it is appropriate for your individual circumstances.

While myo-inositol is not a substitute for monitoring blood sugar levels or following the advice of your diabetes team, it may be another tool that some people find helpful when managing fasting blood sugar levels.

You Can Only Do So Much

One of the most frustrating things about high fasting blood sugar levels is that they are often much harder to influence than post-meal blood sugar readings.

Many people find they can keep their after-meal levels within target range but continue to struggle with fasting levels despite carefully following their meal plan, staying active, drinking plenty of water, trying different bedtime snacks, and making other lifestyle changes.

This is because fasting blood sugar levels are heavily influenced by pregnancy hormones and increasing insulin resistance. As pregnancy progresses, these hormonal changes can make fasting levels increasingly difficult to control, regardless of how hard you are trying.

If you have made changes to your diet and lifestyle but your fasting levels remain above target, please don’t blame yourself.

High fasting levels are extremely common in gestational diabetes and are often the hardest readings to control.

In 2024, Gestational Diabetes UK conducted a survey of 3,270 people diagnosed with gestational diabetes. Almost half (49%) reported fasting blood sugar levels above their recommended target range.

This highlights just how common high fasting levels are and why many people require additional support from medication or insulin during pregnancy.

Needing medication or insulin does not mean you have failed. For many people with gestational diabetes, it is simply the additional support their body needs to overcome increasing insulin resistance and achieve blood sugar levels within their target range

Remember: High fasting blood sugar levels are often driven by hormones and insulin resistance rather than a lack of effort. If your fasting levels remain high despite making changes, you are not failing, and you are certainly not alone.

Medication and Insulin

For many people with gestational diabetes, lifestyle changes alone are not enough to bring fasting blood sugar levels within their target range.

This is particularly true when fasting levels are being driven by increasing insulin resistance and pregnancy hormones rather than food choices alone.

If your fasting levels remain above target despite making dietary and lifestyle changes, your diabetes team may recommend medication such as Metformin, insulin, or a combination of both.

Being prescribed medication or insulin does not mean you have failed. It simply means your body needs additional support to manage the increasing insulin resistance that occurs during pregnancy.

Many people who require medication have already done everything they can with diet, activity, hydration and bedtime snacks, yet still experience high fasting blood sugar levels.

Insulin

Insulin is often recommended when blood sugar levels remain above target despite dietary changes, activity, and medication such as Metformin.

Many people are surprised to learn that needing insulin is very common in gestational diabetes, particularly when fasting blood sugar levels are elevated.

Unlike Metformin, insulin starts working immediately after it is injected. However, this does not necessarily mean blood sugar levels will improve straight away.

Insulin doses are intentionally started low to reduce the risk of hypoglycaemia (low blood sugar levels). Your diabetes team will then gradually adjust the dose until blood sugar levels are within target range.

As pregnancy progresses, insulin resistance usually increases. This means insulin doses often need to be adjusted regularly throughout pregnancy.

If you have been advised to increase your insulin dose, this does not mean your gestational diabetes is getting worse or that you have failed. It simply reflects the increasing insulin resistance caused by pregnancy hormones.

Many people require several dose adjustments before they find the amount of insulin that works best for them.

Why Haven’t My Levels Improved Yet?

Many people feel discouraged when they start Metformin or insulin and still wake up to high fasting blood sugar levels.

This is extremely common.

Metformin can take time to build up in the body before its full effect is seen. Insulin starts working immediately, but the dose may not yet be high enough to overcome increasing insulin resistance.

It is also important to remember that insulin resistance often increases throughout pregnancy, particularly during the second and third trimesters. This means your medication requirements may change over time.

For many people, managing gestational diabetes involves gradually adjusting medication and insulin doses until blood sugar levels are consistently within target range.

If your fasting blood sugar levels remain high despite medication or insulin, do not wait until your next appointment. Contact your diabetes team to discuss whether dose adjustments may be needed.

Many people require multiple dose increases before seeing the improvement they are hoping for.

Why Are Fasting Blood Sugar Levels Important?

Fasting blood sugar levels provide an indication of your baseline blood sugar control and can help show how well your body is managing glucose overnight.

Research has consistently shown that higher fasting blood sugar levels are associated with an increased risk of pregnancy complications, which is why diabetes teams place so much emphasis on keeping fasting levels within their recommended target range.

While both fasting and post-meal blood sugar levels are important, studies suggest that elevated fasting levels may be particularly associated with adverse pregnancy outcomes.

This is one of the reasons fasting levels often receive so much attention during gestational diabetes care.

Higher Fasting Levels and Pregnancy Outcomes

Research has linked elevated fasting blood sugar levels with an increased risk of complications including:

• Large for gestational age (LGA) babies

• Hypertensive disorders of pregnancy

• Induction of labour

• Caesarean birth

• Shoulder dystocia

• Neonatal intensive care unit (NICU) admission

• Neonatal hypoglycaemia

A large Canadian study of more than 250,000 pregnancies found that elevated fasting glucose levels were more strongly associated with adverse pregnancy outcomes than elevated post-meal glucose levels.

The researchers concluded that fasting glucose levels were a particularly important predictor of both large for gestational age babies and hypertensive disorders of pregnancy.

Future Risk After Pregnancy

For most people, gestational diabetes resolves after birth once the placenta has been delivered and pregnancy hormones rapidly decrease.

However, having gestational diabetes does increase the risk of developing gestational diabetes again in future pregnancies and increases the risk of developing prediabetes or type 2 diabetes later in life.

Research has shown that elevated fasting blood sugar levels during pregnancy are one of the strongest predictors of future type 2 diabetes risk.

This does not mean that developing type 2 diabetes is inevitable. Many factors influence future risk, including genetics, weight, lifestyle, activity levels, and overall health.

The good news is that there are steps you can take after pregnancy to help reduce your risk, including:

• Attending your postnatal diabetes screening test

• Maintaining regular physical activity

• Following a balanced diet

• Managing weight where appropriate

• Attending future diabetes screening when invited

Gestational diabetes can be viewed as an early warning sign that your body may be more vulnerable to insulin resistance. Knowing this allows you and your healthcare team to take steps to monitor and protect your long-term health.

Remember: High fasting blood sugar levels are one of the most common and frustrating aspects of gestational diabetes. While lifestyle changes may help, fasting levels are heavily influenced by pregnancy hormones and insulin resistance. If you need Metformin or insulin to keep your levels within target range, this does not mean you have failed. You are simply giving your body the support it needs during pregnancy.