High fasting levels

High fasting levels

High fasting levels are a huge problem for many ladies. Fasting blood sugar levels, levels taken first thing in the morning when you wake up, are the hardest thing to control with gestational diabetes.  But why is that?

When we're sleeping we are not eating and drinking and we are not active and so the body is left to it's own devices with regards to controlling blood sugar levels.

High fasting levels

Impacts on fasting blood sugar levels

Many things can impact fasting levels:

  1. what you've eaten earlier in the evening
  2. when you last ate
  3. hydration levels
  4. how well you've slept
  5. the dawn phenomenon
  6. the Somogyi effect
What you ate earlier in the evening

Bearing in mind how much of each food group converts to glucose in the bloodstream and the time taken, your fasting levels may be impacted by this.

Too much carbohydrate in your evening meal or as a snack before bed can contribute to high fasting levels, as your body can only produce or use so much insulin, so if you raise your blood sugars too high by eating too much carbohydrate, your body can spend the night battling to try to lower your blood sugar levels.

A high fat meal such as takeaway food can also cause higher blood sugar levels and so eating a well paired evening meal is important.

Macronutrients impact on blood glucose

When you last ate

The key to stabilising blood sugar levels is to eat small amounts, often. We obviously cannot do this throughout the night, but if you eat your evening meal early and do not eat again until breakfast the following day, it can be an extremely long time to go without eating. Likewise, if you eat a large meal just before going to bed, this too can have a detrimental effect on your fasting levels.

Hydration levelsdrink water

Dehydration will cause higher blood sugar levels. Water helps to flush excess sugar from the body and so it is important to stay well hydrated.  Some ladies find it helps to take a big glass of water to bed with them so that they can also drink when waking to go to the bathroom in the night.

How well you've slept

Insufficient and poor sleep quality can lead to higher blood sugar levels. Not easy when you are pregnant anyway, but a good nights sleep will help blood sugar levels

Two more possible contributing factors to high fasting levels

facebookAlthough lots of research publications for other types of diabetics, there is little research on the following two matters in gestational diabetes.  Although we know through the posts seen in our Facebook support group that fasting levels are a huge problem to mothers with gestational diabetes

Dawn phenomenon

sunrise-165094_1280 (2)This occurs when the body releases hormones in the early hours of the morning (hence the 'dawn') in all people, diabetic and non-diabetic.  These hormones (including cortisol, glucagon, epinephrine and growth hormone) cause blood sugar levels to rise, giving the body a boost and wake up call to start the day.  This can happen anywhere between 3am and 8am.

In diabetics not enough insulin is produced, or insulin is not able to be used effectively in order to process this boost in glucose, resulting in high fasting levels.

Somogyi effect

Contested by some professionals and researchers; named after the doctor who first wrote about this, Somogyi, also known as the 're-bound hyperglycaemia'.  It only effects some diabetics, not all. When blood sugar levels drop low in the night (hypoglycaemia), the body responds by dumping glucose in order to raise blood sugar levels.

Possible ways to try to lower fasting levels
  • Go for a walk after your evening meal - exercise has a insulin type effect on the body's cells which can impact many hours after and so may help lower fasting levels
  • Eat less carbohydrates in your evening meal - although remember that it is important to still eat sufficient carbohydrates to avoid ketosis, so carbs must not be completely cut from the meal
  • Drink plenty of water - take a glass of water to bed and have a drink when waking in the night
  • Eat a bed time snack - eating a snack before bed has been the biggest success with ladies in our support group.  A snack which is high in protein and natural fat is said to work best. Start with something like a couple of oatcakes and cheese, or a Ryvita with peanut butter. If this does not impact fasting levels, then try a high protein snack without any carbohydrates.
  • apple cider vinegarApple cider vinegar - drink 2 tbsp apple cider vinegar at bedtime with 1 oz (a thumb size piece) of cheese. A small study in type 2 diabetic patients found that drinking 2 tbsp of apple cider vinegar and eating 1 oz cheese lowered fasting levels by 4% (and up to 6% in some patients).

Some ladies with gestational diabetes have had great success with apple cider vinegar and so it's worth trying if you have the stomach for it!

Please note: As vinegar is acidic, it is advisable to dilute it in some water and brush teeth after consuming

I've tried a bedtime snack and it's not working?

We often get ladies in our support group saying "I've tried a bedtime but it doesn't work for me", yet when asking what they've tried they've had fruit or toast etc.

The best things to eat are high protein and high natural fat. 

nuts, seeds, peanut butter
high protein and natural fat works best as a bedtime snack. Nuts are an ideal source

Bedtime snacks may take some playing around with to find what works best for you. As your pregnancy progresses and your insulin resistance increases, you may need to change to find things that work better.

A bedtime snack does not work for everybody.

Depending on what is eaten, some ladies see higher fasting levels from eating bedtime snacks, but many that have eaten bedtime snacks have had good success.

Please note: It is very common to be advised not to eat after a certain time of day by your dietician or diabetic team. This causes some huge problems for shift workers, night workers, or those that eat late in the evening.  Our advice of eating little and often may be contested by the advice given to you by your team.  Only you can be the judge of this and see what works best for you, but eating little and often (no matter the time) and having bedtime snacks has been successful for the majority of our support group members.

Metformin_ElizabethMedication and insulin

High fasting levels are very common with gestational diabetes and are the hardest level to control. For the majority struggling with high fasting levels, the only way to improve them is with the help of medication such as Metformin and/or insulin.

By being prescribed medication and insulin to control your blood sugar levels, you should not feel you have failed.  For many it is the only way to achieve good fasting levels when all other methods above have been tried.


Bedtime snacks used alongside medication/insulin have helped many ladies keep doses lower for longer and so you may want to try snacking even if you are being medicated for fasting levels.

Why are fasting levels important?

Fasting levels give an indicator of our baseline blood sugar levels. This shows an picture of what our levels are returning to when they are not complicated by the foods we are eating.

Some may struggle with fasting levels, yet post meal levels stay well controlled and vice versa. For others that are more insulin resistant, they may struggle with both fasting and post meal levels.

Both high fasting and high post meal levels should be lowered and controlled to help minimise complications caused by gestational diabetes.

A 2002 publication from Diabetes Care comparing 28 studies found that elevated fasting levels during pregnancy was the most common risk factor associated with future risk of type 2 diabetes:

Cumulative incidence of type 2 diabetes increased markedly in the first 5 years after delivery and appeared to plateau after 10 years. An elevated fasting glucose level during pregnancy was the risk factor most commonly associated with future risk of type 2 diabetes.


Fasting hyperglycemia: etiology, diagnosis, and treatment

The dawn phenomenon and the Somogyi effect - two phenomena of morning hyperglycaemia

The dawn phenomenon revisited: implications for diabetes therapy

Sleep Duration and Blood Glucose Control in Women With Gestational Diabetes Mellitus

Sleep Disturbances and Gestational Diabetes Prevalence on Last Trimester of Pregnancy