EXPLAINER: Low blood sugar – what are its symptoms, and how do you prevent it?

A woman draws blood from a patient's middle finger using a lancet to run low blood sugar test.
Following the fainting of CNA presenter Julie Yoo live while covering the United Nations-led COP27 2022 climate talks, here's an explainer on low blood sugar symptoms and preventions. (PHOTO: Getty Images)

In the midst of covering the United Nations-led COP27 2022 climate talks, CNA presenter Julie Yoo fainted live on air on the news channel's Asia Tonight programme on Wednesday (9 November).

CNA's parent company Mediacorp said in a statement that Yoo had felt “unwell due to dehydration and low blood sugar” following the incident.

What exactly is low blood sugar and how do we watch out for its symptoms?

Low blood sugar (hypoglycemia)

Low blood sugar level, or hypoglycemia, occurs when the level of sugar (glucose) in a person’s blood drops too low. It can be caused by medications, delayed meals, too much exercise, alcohol on an empty stomach, or declining kidney function, among others.

Hypoglycemia can happen to anyone but is more common with diabetics, according to Dr Amanda Lam, a Consultant Endocrinologist at the Singapore General Hospital (SGH).

"Symptoms of low blood sugar (hypoglycemia) are unpleasant and may interfere with your daily activities. Serious hypoglycaemia may cause accidents, seizures, coma and death. Fortunately, there are ways to recognise, treat, and prevent hypoglycemia," shared Dr Lam in a piece on

Signs and symptoms

If you think you’re at risk, here are the early signs of hypoglycemia you should watch out for:

  • Shakiness

  • Sweating

  • Fast heartbeat

  • Headaches

  • Dizziness

  • Tingling sensation in your fingers, lips or tongue

  • Feeling hungry or nauseous

  • Feeling nervous or anxious

  • Feeling irritable

Hypoglycemia can also cause severe symptoms such as:

  • Weakness and difficulty walking

  • Blurred vision

  • Confusion and abnormal behaviour

  • Slurred speech

  • Loss of consciousness

  • Seizures

If you have severe symptoms, you should call an ambulance immediately or ask the people around you to help.

How to treat low blood sugar

According to Dr Lam, if you experience early signs of hypoglycemia, you can mitigate it by eating or drinking 15 grams of fast-acting carbohydrates immediately.

Even if you cannot check your blood sugar immediately, you can eat or drink the following, just to be safe:

  • 4-5 glucose tablets

  • Half a can of soft drink (150ml-200ml)

  • Half a glass of fruit juice (150ml)

  • 3 teaspoons of sugar with half a cup of water

Avoid the following types of food:

  • Any food or drink containing fat or protein

  • Any food that requires a lot of prolonged chewing/sucking

What to do next?

Using the 15/15 rule, after eating 15g of fast-acting carbohydrates, test or re-test your blood glucose with a glucometer after 15 minutes.

If your blood glucose is still less than 4.0 mmol/L, consume another 15g of fast-acting carbohydrates, re-test blood glucose, and repeat as long as your blood glucose does not rise more than 4.0 mmol/L.

If your blood glucose is more than 4.0 mmol/L, look out for your blood glucose level as it may fall again after 1 hour.

You may eat an additional food containing 15g of long-acting carbohydrates such as biscuits (3 pieces) or bread (1 slice).

How to prevent hypoglycemia

To avoid low blood sugar and the inconvenience and danger it poses, here are some tips from Dr Lam:

  • Take your diabetes medication regularly as recommended by your doctor.

  • Eat nutritious meals and time them to balance your diabetes medication.

  • Monitor your blood sugar level regularly based on your doctor’s recommendation.

  • Adjust your food intake and medication according to your exercise routine.

You may also ask your friends or family to look out for you if you’re prone to hypoglycemia so they know what to do, just in case. Stay safe!

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