Do you experience overnight glucose lows? Read about the common causes of low blood glucose levels overnight and what is considered normal.

Overnight decreases in blood glucose readings, or overnight hypoglycaemia, is common and often a point of intrigue for people exploring their metabolic wellbeing. This article will help you understand what might be going on and how to explore this further.

What is the link between glucose and sleep?

Blood glucose levels and sleep are intimately related. They have a bi-directional relationship — how well you sleep will impact your blood glucose levels the following day, and your blood glucose levels will impact how you sleep that night. Your glucose levels can contribute to frequent waking and feelings of having an unrefreshing sleep. Of course, food choices, exercise timing and stress levels all play a role in this bi-directional relationship.

What is a normal glucose reading during sleep?

It’s normal to experience blood glucose fluctuations during sleep. The evidence shows us that many people’s blood sugar drops by about 5% during REM sleep compared to non-REM sleep.

Research suggests that the optimal fasting glucose levels upon waking for non-diabetics in a fasted state should be between 3.9-5.6 mmol/L, with overnight glucose levels fluctuating between 3.9-5.6 mmol/L.

What are the symptoms of low blood sugar levels?

There are many symptoms of low glucose levels. It’s important to discuss your symptoms with your doctor. Common symptoms include:

• Sweating
• Shaking
• Hunger
• Dizziness
• Feeling anxious
• Mood changes, such as irritability

What causes overnight glucose lows?

There are many causes of overnight hypoglycaemia. If you’re concerned, it’s important to express this to your doctor so they can investigate. We’ll discuss a few common causes in this article — but know there are many more!

Alcohol consumption

One of the most common causes of low blood glucose overnight is alcohol consumption, especially if consumed on an empty stomach.

Alcohol is a toxin to the body, and it directly alters the liver’s ability to make new glucose (gluconeogenesis). If there is alcohol in the bloodstream, the body will utilise this as energy before it uses glucose. This leads to glucose uptake by the cells and without alcohol consumption, the liver will be stimulated to release more glucose. However alcohol blocks the liver's ability to do this, and will therefore drop blood sugar levels.

Eating late

Eating late at night, particularly a carbohydrate-loaded meal, may result in an excessive release of insulin. This leads to too much glucose entering the cells, leading to reactive hypoglycaemia.

Reactive hypoglycaemia is usually accompanied by symptoms such as wakefulness, irritability, hunger, clamminess, sweatiness, anxiety, restlessness and nightmares. It may be an early sign of metabolic syndrome or diabetes, so it is important to take note of it. It can often be managed by lifestyle changes such as optimising your diet, limiting simple sugar and processed foods, exercising and managing your stress.

Medications

Many medications impact the way the body processes glucose. Both long-term medications such as ACE inhibitors or salicylates or short-term medications like antibiotics can impact the insulin-glucose balance. If you experience dips in blood glucose and take medications on a regular basis, discuss this with your prescribing doctor.

For a full list of medications that impact glucose control, please speak to your GP or pharmacist.

Sleeping on your CGM

If you’re wearing a continuous glucose monitor (CGM), you may notice that sleeping on the CGM can result in low glucose readings. Pressure-induced changes may be worth considering if you feel well-slept, maintain regular glucose levels otherwise and do not experience the common symptoms of hypoglycaemia as presented above.

Wearing a CGM is a fantastic way to monitor your glucose levels and observe how your lifestyle impacts your metabolic health. They are a wonderful tool to help you understand how to improve your metabolic health to suit your individual body. The Vively app combines CGM with personal dietitian support and lifestyle education to help you improve your metabolic health and feel your best, check it out now.