It’s becoming increasingly common for people to focus on keeping their blood sugar levels low to improve their health and longevity. But what many people don’t know is that blood sugar falling too low can be dangerous. 

Normally, your levels fluctuate throughout the day, even when you’re sleeping, and are affected by many factors, including food, exercise, and stress (1). 

People with diabetes often struggle to keep their blood sugar levels stable. They can sometimes experience low blood sugar, also known as hypoglycemia, due to their medications.  

But even people without diabetes can develop low blood sugar due to drugs, diets, and intense exercise.

Let’s take a closer look at what causes hypoglycemia in people without diabetes, plus symptoms to look out for – when you should be alarmed. 

What Is Low Blood Sugar or Hypoglycemia?

Low blood sugar, or hypoglycemia, refers to a condition in which your blood sugar drops below normal levels, usually considered to be below 3.9 mmol/L (70 mg/dL) (2).  

Sugar in the form of glucose is the main source of fuel for your cells. That’s why the body has evolved many different ways to keep glucose levels in a normal range. This requires complex coordination between specific hormones, glands, organs, and cell receptors. 

When this system gets disrupted, blood sugar levels can get too high or too low. 

What Are the Symptoms of Hypoglycemia?

When your body fails to maintain normal blood sugar levels and they fall too low you may experience lightheadedness, dizziness, and sweating (2).  

Other hypoglycemia symptoms include: 

• Fatigue 

• Hunger

• Shakiness

• Difficulty concentrating

• Irregular or increased heart rate

Many of these symptoms result from the brain not getting enough glucose to fuel itself. Because glucose is essential for the brain to function properly, low levels will affect many different aspects of cognition. 

Nocturnal hypoglycemia occurs at night and may include nightmares, night sweats, and waking up fatigued or with a headache.

What Are the Common Causes of Hypoglycemia in Persons Without Diabetes?

Hypoglycemia can also occur in people who do not have diabetes due to a variety of reasons.

1. Eating Too Many Carbs In One Meal

One of the most common reasons for hypoglycemia in people without diabetes is eating too many carbohydrates or sugars in one sitting. 

When you eat a large amount of fast-digesting carbohydrates like pasta or white rice in a short period of time, they’re quickly broken down into glucose, spiking your blood sugar levels. The pancreas helps control blood sugar by releasing insulin, which shuttles the glucose into your cells. When you eat too many carbs, the pancreas has to release much more insulin than normal. 

However, sometimes too much insulin is released, which can drive your blood sugar levels down too far. This can lead to hypoglycemia. 

This process is known as reactive hypoglycemia. It usually occurs within two to five hours after a meal. It is more likely to occur in meals that don’t include fibre or protein to slow the absorption of sugar (3).  

Reactive hypoglycemia isn’t too serious and can usually be corrected by eating 10-15 g of sugar and checking your blood sugar every 15 minutes. Repeat this process until your levels return to normal.

2. Very Low-Carbohydrate Diets

Low carbohydrate diets are often touted to help with weight loss and blood sugar control. 

One of the most popular low-carbohydrate diets in recent years is the ketogenic diet. It involves eating very low levels of carbohydrates to keep your body in a fat-burning state, also known as ketosis. 

Over the years, there have been multiple reports of hypoglycemia in people following a ketogenic diet (4). 

Because you’re not consuming a lot of carbohydrates on a ketogenic diet, your blood sugar levels will naturally be lower. 

Normally when your blood sugar levels get too low, your body senses it and tells your liver to start releasing glucose to meet its needs. However, if you have been on a ketogenic diet for an extended time, your glucose stores in the liver may be low. If your liver is not able to release glucose into your bloodstream, you can develop hypoglycemia. 

3. Exercise 

Exercise is great at lowering blood sugar levels (5). However, if you exercise too hard and for too long without replenishing your carbohydrate (glycogen) stores it could lead to hypoglycemia (6). 

As a general guide, you may consider taking 3-5g of carbohydrate per kilo of body weight per day. This is for those who exercise 3-4 times a week for 30-60 minutes per day. Roughly that’s about 180g-300g of carbohydrates per day for someone who is 60kg. 

If you exercise 5-6 times a week for 2-3 hours per day, you need to consume 5-8g per kilo of body weight per day. That amounts to 300g-480g of carbohydrate per day for someone who is 60kg.

Usually, for exercise less than 60mins (or even 90mins), our body's natural intake and accumulation of carbs throughout the day and week should be able to sustain a training session normally without the need to load carbs deliberately. However, if you’re doing an event that is more than 60 minutes, you should refuel 30-60g of carbohydrates every hour.

4. Alcohol

Alcohol increases the body’s insulin response to food and blocks the liver’s ability to make glucose (7, 8).  Drinking–especially binge drinking–on an empty stomach can increase the risk of hypoglycemia in some people (9).  To make matters worse, alcohol can also make you less aware of any hypoglycemia symptoms you may experience (10). 

Make sure you have some food in your system before enjoying yourself and pay especially close attention to how you’re feeling. 

5. Medications and Supplements

Certain medications can interfere with the body’s ability to maintain healthy blood sugar levels. 

These include (11): 

• Certain blood pressure medications

• Certain antibiotics

• Epilepsy medications

• Heparin used to prevent blood clots

• Malaria drugs

• Lithium

Taking diabetic medications when you don’t have diabetes can also cause hypoglycemia.

Metformin is a drug commonly used by diabetics to control blood sugar levels. It has become popular in certain health circles for its purported longevity effects. There are even multiple trials currently being run to see if metformin can slow down certain aspects of ageing (12).  

There are also a few supplements as powerful as metformin that are often used by healthy people to control their blood sugar levels. The most notable are berberine and alpha-lipoic acid (13, 14).

If you experience hypoglycemic symptoms with any of these medications, check in with your healthcare provider to determine how best to mitigate the side effects you are experiencing.

When or How To Know If the Hypoglycemia Event Is Cause For Alarm

If your blood sugar levels drop below 3.9 mmol/L (70 mg/dL) and you’re not experiencing any symptoms, you shouldn’t be too concerned. Studies have shown that in otherwise healthy individuals, blood sugar levels can go below 3.9 mmol/L (70 mg/dL) for 2.8 hours a day, and even, below 3.3 mmol/L (60 mg/dL) for 1 hour a day.(15)

If your levels are low and you do start to experience symptoms of hypoglycemia, this isn’t necessarily cause for alarm either. However, you should take steps to quickly resolve it. 

Try consuming 10-15 g of carbohydrate in the form of fruit or a sugary snack and continually check your blood sugar levels and monitor your symptoms. Wait 15 minutes and then consume another 10-15 g of carbohydrates and test your levels, repeating this until they return to normal.

If your blood sugar levels do not rise after consuming carbohydrates and you continue to experience symptoms, then this signifies something serious. You should call 995 or have someone drive you to the hospital as soon as possible. 

Benefits of Maintaining Stable Glucose Levels Throughout the Day

Keeping your blood sugar levels without large swings in either direction is incredibly beneficial for your overall health and vitality. 

Stable blood sugar levels ensure that your energy levels stay constant and you don’t crash after that big lunch. Since the brain requires glucose, maintaining your sugar levels means having enough energy to focus and think without being overstimulated.

Controlling your levels also reduces your chances of developing diabetes and heart disease later on in life (16, 17).

Keeping your levels stable can also help you achieve your weight loss goals. Dramatic swings in blood sugar can trigger cravings, especially for high-calorie, carbohydrate-rich foods (18). 

If you’re a healthy person experiencing hypoglycemia, the most likely causes are eating too many carbohydrates at once, not eating enough carbohydrates, intense exercises, alcohol, and certain medications. In most of these cases, hypoglycemia can be addressed by eating a small amount of carbohydrates and monitoring your blood sugar levels.