Updated 24th April 2024

How to spot hypoglycemia, or low blood sugar, and how to control it

Share this article

  • Share on Facebook
  • Share on Twitter
  • Print this page
  • Email this page

Hypoglycemia, or low blood sugar, is most commonly a symptom of diabetes. It can be caused by not using insulin correctly, excessive exercise, skipping meals, and other factors. 

Hypoglycemia can occasionally affect people who don’t have diabetes if they’re on certain medication, have poor nutrition, or as a symptom of other health conditions. 

Certain foods can also lead to periods of lower blood sugar after you eat.

ZOE runs the largest scientific study of nutrition in the world, with over 15,000 participants to date. Our research has shown that everyone’s blood sugar responses are different, even if they eat the same food. 

Over time, these responses can affect your risk of health conditions like type 2 diabetes.

ZOE’s at-home test analyzes your blood sugar and blood fat responses to food. Using this information, we give you personal insights into which foods are best for your unique metabolism.

You can take a free quiz to find out more.

Read on to learn more about the causes and symptoms of hypoglycemia or low blood sugar, whether you have diabetes or not, and what to do about it. 

What is hypoglycemia?

Hypoglycemia is when the level of sugar in your blood drops too low. There are personal differences, and what may be a normal glucose value for one person may not be for another. 

Generally, glucose values less than 70 mg/dL, or 4 mmol/L, are considered to be within the hypoglycemic range. 

For people with diabetes, the target glucose level to avoid hypoglycemia is for blood sugar levels to stay above 70 mg/dL, or 4 mmol/L. For people without diabetes, where it’s much rarer, hypoglycemia is usually well tolerated until blood sugar is less than 55 mg/dL, or 3 mmol/L.

The amount of time your blood sugar spends in these ranges is also important. With new developments in technology such as continuous glucose monitoring, we can now measure how much time people actually spend in their ideal or target glucose range. 

Although more research is needed, experts believe that for people with diabetes, the more time you’re outside a healthy range, the more likely you are to experience diabetes complications

For people without diabetes, your doctor may look at how long your levels stay low, and how often this happens, to help decide whether you have clinically significant hypoglycemia that needs further investigation and potential treatment.

While individual goals vary, experts generally recommend that your blood sugar is not within these low ranges for more than 4% of the day, or about 1 hour for people with diabetes.

What are the symptoms?

You could experience a variety of different symptoms when your blood sugar is too low. Some are generally mild, while others can be very serious.

Some mild symptoms include:

  • feeling shaky, jittery, dizzy, or lightheaded

  • hunger

  • headaches

  • trouble thinking or speaking clearly

  • mood changes

If your low blood sugar levels are untreated for too long, it could lead to potentially life threatening conditions, such as loss of consciousness, seizures, or heart attack.

Join our mailing list

Sign up for fresh insights into our scientific discoveries and the latest nutrition updates. No spam, just science.

Causes of hypoglycemia

For people living with diabetes, low blood sugar can be caused by a variety of factors, such as:

  • taking too much insulin or the wrong type

  • taking insulin at the wrong time

  • skipping or delaying meals

  • not eating enough carbohydrate

  • too much or too intense exercise

  • drinking too much alcohol

It's important to recognize symptoms of hypoglycemia and to treat them quickly.

If you find that your blood sugar is falling low — and only if symptoms are not severe enough to seek immediate medical attention — it’s recommended that you follow the 15-15 rule, where you eat 15 grams of quickly digested carbohydrates and test again 15 minutes later. 

If your blood sugar is still too low, repeat this process until it returns to a normal range.

Sometimes, a prescription-grade glucagon treatment may be needed. Talk to your doctor to discuss whether you should have a glucagon treatment standing by, and how and when to use it.

Low blood sugar in people without diabetes

Hypoglycemia is rare in people without diabetes. However, it can be caused by:

  • certain medications, including quinine, taken for malaria

  • poor nutrition

  • gastric bypass surgery

  • complications of pregnancy 

  • certain health conditions, including those that affect hormone levels

While hypoglycemia is unusual for people without diabetes, they can still experience lower than normal blood sugar.

After you eat, carbohydrates are broken down into glucose, or sugar. This enters your bloodstream, causing blood sugar levels to rise.

The sugar in your blood is transported to your cells to be used as energy or stored for later. As your cells take in the sugar, your blood sugar levels drop.

Small ups and downs in blood sugar are normal, but levels typically don’t properly drop down into the hypoglycemic range. 

If you don’t have diabetes and experience mild symptoms like being tired, feeling a bit shaky, or experiencing a change in mood after a meal, it might be a good idea to check your glucose levels a few times to see if there is a pattern.  

When you eat foods that lead to sharp “spikes” and “crashes” repeatedly, it can have negative effects on your health.

ZOE's research also shows that blood sugar dips after a meal can lead to increased hunger and eating more food, even the following day.

If regularly repeated, these bigger changes to your blood sugar levels can have more serious implications. They can increase your risk of developing metabolic diseases, such as type 2 diabetes, chronic inflammation, and heart disease.

Eating for better blood sugar control

The particular foods you eat make a big difference to your blood sugar responses. In general, you can lower your chances of spikes and crashes by focusing on good quality, wholefood sources of carbohydrates, instead of those that are highly processed.

Try to limit ultra-processed sources of carbs, including:

  • most breakfast cereals

  • snack foods like chips, cookies, and candy

  • soda and other sweetened drinks

Instead, focus on minimally processed carbs, like:

  • whole grains, including whole-wheat pasta, whole-grain bread, and oats

  • fruits and vegetables

  • beans and pulses

However, that’s not the whole picture.

At ZOE, we run the world’s largest nutritional study. The data we’ve collected show that everyone responds to foods differently.

Our at-home test can help you to understand your personal blood sugar and blood fat responses to hundreds of foods.

You can also learn about the “good” and “bad” bacteria that live in your gut. These are involved in your responses to food, too, and are linked to your risk of some of the same metabolic diseases. 

The ZOE program uses this data to help you choose the best foods for your body, which can help you regulate your blood sugar levels.


Hypoglycemia, or low blood sugar, is more common for people living with diabetes

In people with diabetes, hypoglycemia can be caused by factors including incorrect insulin use, not eating the right foods at the right time, and drinking alcohol. 

In people who don’t have diabetes, certain medications, poor nutrition, and other health conditions can sometimes lead to hypoglycemia.

Rises and falls in blood sugar after eating can also result in lower than normal levels. This depends on the foods you eat and your body’s specific responses to them.

The ZOE program can help you to understand these responses and eat the best foods for your health. 

You can take a free quiz to find out more.


Carbohydrates and blood sugar. (n.d.) https://www.hsph.harvard.edu/nutritionsource/carbohydrates/carbohydrates-and-blood-sugar/

CGM & time in range. (n.d.). https://www.diabetes.org/tools-support/devices-technology/cgm-time-in-range

Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time in range. Diabetes Care. (2019). https://diabetesjournals.org/care/article/42/8/1593/36184/Clinical-Targets-for-Continuous-Glucose-Monitoring

Diabetes complications. (n.d.). https://medlineplus.gov/diabetescomplications.html

Hypoglycemia. (2022). https://www.endocrine.org/patient-engagement/endocrine-library/hypoglycemia

Hypoglycemia (low blood sugar). (n.d.). https://www.diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hypoglycemia

Hypoglycemia: The neglected complication. Indian Journal of Endocrinology and Metabolism. (2013). https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC3784865/

Low blood glucose (hypoglycemia). (2021). https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia#symptoms

Low blood sugar (hypoglycemia). (2020). https://www.nhs.uk/conditions/low-blood-sugar-hypoglycaemia/ 

Non-diabetic hypoglycemia. Endotext. (2020). https://www.ncbi.nlm.nih.gov/books/NBK355894/

Non-diabetic hypoglycemia. The Journal of Clinical Endocrinology & Metabolism. (2013). https://academic.oup.com/jcem/article/98/10/39A/2833323

Postprandial glycaemic dips predict appetite and energy intake in healthy individuals. Nature Metabolism. (2021). https://www.nature.com/articles/s42255-021-00383-x

Share this article

  • Share on Facebook
  • Share on Twitter
  • Print this page
  • Email this page