What is low blood sugar? Symptoms, causes & prevention

Glucose is the body’s main source of energy, and we need a steady amount of it for our cells, organs and tissues to function properly. When our blood glucose level drops too low, we can experience dizziness and fatigue and sometimes more severe symptoms if blood sugar level is not restored to normal. It can be very serious if left untreated, but it is often something you can treat easily yourself when you know what to do. Low blood sugar is also called hypoglycaemia, and it is most common in diabetics, though it can sometimes happen to non-diabetics. In this guide, we explain the causes of low blood sugar, the symptoms to look out for and how to prevent and treat hypoglycemia. 

What is low blood sugar?

Low blood sugar, or hypoglycemia, occurs when the body does not have enough glucose. Glucose comes from the foods we eat, mainly through carbohydrates such as whole grains, potatoes and fruit, where it is absorbed by the body to use as energy. The hormone insulin is responsible for moving glucose from the blood into cells for use and storage. When everything is functioning normally, this balance of glucose in the blood to glucose absorbed is well-regulated.

However, in people with diabetes, insulin levels are either lower or their cells don’t respond well to insulin. This results in more blood glucose and high blood sugar. Low blood sugar is most common in diabetics who are taking insulin or medications, as they need more insulin to balance their blood sugar. Sometimes this balance tips the other way, resulting in hypoglycemia.

Although low blood sugar is more common in those with type 1 and type 2 diabetes, it can sometimes happen to non-diabetics. There are two types of hypoglycaemia in people without diabetes:

  • Reactive Hypoglycemia – Occurs after a meal
  • Fasting Hypoglycemia – Happens after a period without food

There are many reasons why hypoglycemia occurs in non-diabetics. Below, we’ll explain some of the possible causes of hypoglycemia in diabetics and non-diabetics.

What are the causes of low blood sugar?

As previously mentioned, low blood sugar is most common in people with diabetes. Diabetic hypoglycemia can occur for a number of reasons: 

  • Taking too much insulin or other medications (sulfonylureas, glinides, some antiviral medicines)
  • Exercising too much
  • Delaying or skipping a meal
  • Not eating enough carbohydrates foods in your last meal
  • Drinking alcohol

Non-diabetics may experience a drop in blood sugar after eating a meal (reactive hypoglycemia). Some potential causes for this are: 

  • Having pre-diabetes or being at risk for diabetes
  • Rare enzyme deficiencies that affect your body’s ability to break down food
  • Stomach surgery – such as a gastric bypass – can cause food to pass too quickly into your small intestine which affects glucose absorption

Fasting hypoglycemia can also occur in non-diabetics for the following reasons: 

  • Taking medications such as quinine (for malaria treatment)
  • Serious health conditions including those affecting the liver, heart, or kidneys
  • Malnutrition or anorexia
  • Pregnancy complication
  • Low levels of certain hormones, such as glucagon, epinephrine, cortisol and growth hormone
  • Tumours, including a pancreatic tumour that makes insulin (insulinoma) or one that makes a similar hormone (IGF-II)

Sometimes, the cause of low blood sugar cannot be clearly identified. That’s why it’s important to know the symptoms of hypoglycemia to ensure you’re aware of the possible risks.

What are the symptoms of low blood sugar?

The symptoms of low blood sugar can happen very quickly and can progress into a serious hypoglyceamic episode if left untreated. Knowing the signs and symptoms of hypoglycaemia is often the first step in preventing and treating low blood sugar.

Everyone experiences low blood sugar symptoms differently, but some of the common early signs include:

  • Dizziness
  • Tiredness or fatigue
  • Hunger
  • Feeling shaky or trembling
  • Sweating
  • Turning pale
  • Tingling lips, cheeks or tongue
  • Heart palpitations (fast or pounding heartbeat)
  • Changes in mood: feeling anxious, tearful or irritated

If low blood sugar is not treated, you could develop other symptoms which can be more serious, especially when you’re away from home. These include:

  • Blurred vision
  • Feeling sleepy
  • Feeling weak
  • Confusion or difficulty concentrating
  • Unusual behaviour, slurred speech or clumsiness
  • Fainting or collapsing
  • Having seizures or fits

Seek immediate medical attention if you are experiencing hypoglycemia as a non-diabetic, or if you are diabetic and unresponsive to treatment for hypoglycemia. See below for some essential tips on how to quickly and effectively treat low blood sugar.

How to treat and prevent low blood sugar

Low blood sugar needs to be treated immediately before it causes serious health problems. If you or somebody else is experiencing symptoms of hypoglycemia, here’s what you should do: 

  • Step 1: Have a sugary snack or drink. Some options include a small glass of fruit juice or fizzy drink (non-diet), a small handful of sweets or a piece of fruit. If you have them to hand, 3-6 glucose tablets or 1-2 tubes of glucose gel is also good.
  • Step 2: Wait for 10-15 minutes and see if your symptoms improve. If you’re diabetic, now is a good time to take a blood sugar reading. If there’s little to no change, have another sugary snack or drink, wait 10-15 minutes and then measure your blood sugar again. If your symptoms have improved and you feel better, move onto the next step.
  • Step 3: Eat slow-release carbohydrates to stabilise your blood sugar (bread, pasta, cereals, potatoes). Have carbs in the form of a snack or your main meal, depending on the time of day. 

Usually, you won’t need medical attention once you’ve recovered and if you only experience occasional drops in blood sugar. If the symptoms persist or if you vomit or have a seizure resulting from low blood sugar, then you should consult a doctor or healthcare professional.

Preventing low blood sugar is the best way to ensure you don’t experience symptoms of hypoglycemia. Here’s how to prevent low blood sugar in your daily life: 

  • Eat a balanced diet that’s high in complex carbohydrates (whole grains, potatoes), fibre and protein, but low in sugar and refined carbohydrates (white bread, biscuits etc)
  • Before exercising, eat a carbohydrate snack
  • Drink alcohol with caution – do not binge drink, and make sure to eat a carbohydrate snack afterwards 
  • If you’re diabetic, check your blood sugar level regularly, with either a personal glucometer or continuous glucose monitor (CGM)
  • Ask your doctor how any diabetes medications, exercise or meal routines will affect blood sugar levels
  • Always carry a carbohydrate-rich snack or glucose tablets with you

Determining the cause of low blood sugar is another essential preventative measure. If you are experiencing regular episodes of hypoglycemia or are at risk of diabetes due to your weight, age and genetics, scheduling a blood sugar test is a great way to effectively diagnose any problems.

What is the best thing to eat when your blood sugar is low?

As mentioned above, the best thing to have when your blood glucose is low is a sugary snack or drink. Foods that can raise your blood sugar quickly include:

  • A piece of fruit, like a banana, apple, or orange
  • 2 tablespoons of raisins
  • 15 grapes
  • 1 tablespoon honey or jelly
  • A handful of sweets (e.g. 15 Skittles, 4 Starbursts)
  • 3-6 glucose tablets or 1-2 sachets of glucose gel

Drinks that help include:

  • A small glass of apple, orange, pineapple, or grapefruit juice
  • A small glass of fizzy drink (non-diet soda)
  • 1 tablespoon of sugar dissolved in water

To prevent hypoglycemia from occurring, eat a balanced diet containing complex, slow-release carbohydrates.

How do I stop my blood sugar from dropping at night?

Some people experience low blood sugar during the night (nocturnal hypoglycemia). This might cause you to wake up in the middle of the night, break out into a sweat and cause headaches. To avoid this, here are some of the precautionary measures you can take to stabilise your blood sugar before bed:

  • Make sure to eat a carbohydrate-rich dinner
  • Avoid excessive exercise late at night
  • Limit alcohol consumption at night
  • Check your blood sugar reading before bed
  • Have a sugary snack at your bedside just in case

Is low blood sugar a sign of diabetes?

Although diabetes is the most likely cause of low blood sugar, it is possible to experience a drop in blood sugar as a non-diabetic. Some of the other possible causes are identified earlier in this guide, and sometimes low blood sugar happens for no reason at all.

However, frequent instances of reactive hypoglycemia (low blood sugar after eating) could be an early sign of diabetes. A simple blood sugar test can be used to monitor your risk of developing diabetes. Speak to your doctor or healthcare provider today to discuss any worries or concerns.

Low blood sugar can affect anyone, and we hope this guide has helped you to learn the signs and symptoms of hypoglycemia so you are aware of a possible episode. Everyone responds differently to low blood sugar, so it is best to follow our tips for prevention and organise a blood glucose test if you are experiencing any symptoms.

For more expert tips on staying healthy and making small changes for a better lifestyle, visit the Bluecrest Wellness blog.