Reaching for high-carb foods may not be instinctive when blood glucose is low

  • 22 November 2022

It is possible that choosing high-carbohydrate foods during an episode of low blood glucose isn’t something that humans are able to ‘instinctively do’. A recently published study by researchers from the Bristol BRC and the University of Bristol suggests that young people who experienced an insulin-induced episode of hypoglycaemia did not automatically reach for foods that were high in carbohydrates.

Carbohydrates are essentially made up of sugar molecules (like glucose) and the term ‘hypoglycaemia’ describes a situation when someone’s blood glucose levels are below their body’s normal range. Under normal circumstances, hypoglycaemia causes the body to release certain hormones. These hormones increase blood glucose whilst the body also switches off insulin secretion, as that would tend to push glucose levels down.

Hypoglycaemia also makes the sympathetic nervous system (responsible for making us sweat when we get hot for example) go into overdrive. Many scientists believe that this process causes us to crave carbohydrates, but the craving should stop once our blood glucose returns to normal. However, evidence suggests that managing a hypoglycaemic event is much more complicated and carbohydrate craving may not be ‘instinctive’.

The study team wanted to investigate this theory by looking at what children and adolescents would choose to eat after experiencing low blood glucose. None of the young people had any experience of diabetes or hypoglycaemic episodes They all underwent an insulin tolerance test at the Bristol Royal Hospital for Children as part of their clinical care.

Children and young people undergo these tests when doctors need to find out if their anterior pituitary gland is releasing hormones normally. The anterior pituitary gland is located at the base of the brain. It is responsible for controlling how some hormones are released.

The children in this study were given insulin under very controlled conditions. This caused them to develop hypoglycaemia which was managed by healthcare staff. Our researchers then used a computer programme with pictures of different foods. They asked the children to ‘imagine you can have one of these foods to eat right now.’ The young people could choose from a variety of different sweet and savoury foods that were either low or high in calories and carbohydrates.

Despite experiencing low blood glucose, our researchers found that the young people taking part in the study didn’t automatically reach for more high-carbohydrate foods. They also found that the amount of high-carbohydrate food they chose during the computer task wasn’t affected by their blood glucose levels. This suggests that we cannot rely solely on the body’s automatic responses to help people manage episodes of hypoglycaemia. It also underlines the importance of preparing people and educating them on how to manage these episodes.

Hypoglycaemia affects people with diabetes, especially if they must take insulin. Most people with diabetes are given specific guidance on what to do in the event of a hypoglycaemia episode and how to treat it themselves. Having low blood glucose can be dangerous if it isn’t treated quickly enough. Inappropriate or inadequate treatment can lead to seizures, coma or even death.

Sarah Sauchelli, lead author, said:

“When people with insulin-dependent diabetes experience hypoglycaemia (low blood sugar) they need to eat a specific amount of high-carb, low-protein/fat foods to avoid major complications. Not an easy task for many!

“This study provides further evidence that treating a hypoglycaemic event is not instinctive but requires knowledge and preparation. It reinforces the importance of diabetes education, particularly for children and adolescents with insulin requiring diabetes.”

Julian Hamilton-Shield a co-author who manages young people with diabetes, said:

“This emphasises to me how important it is that people living with diabetes, have instant access to the correct, fast-acting, high-carbohydrate rescue packages. Having these to hand at all times, reduces to a minimum, any need to think what to take when faced with hypoglycaemia.”


Preference for high-carbohydrate foods does not change for children and adolescents in insulin-induced hypoglycemia

Sarah Sauchelli1, Peter J Rogers, George Fry, Julian P Hamilton-Shield