Causes of hypoglycemia and what to do when blood glucose levels are low

Doctors prescribe diabetes medications for treating high blood sugar but these medications can sometimes lead to hypoglycemia (low blood sugar levels). Most health topics tend to focus on high blood sugar levels, but low sugar levels can also be dangerous and potentially life-threatening.

A Black man sitting on an office desk with hand placed on his head, looking tired and exhausted

Key takeaways

  • Hypoglycemia occurs when the blood glucose level falls below 70 mg/dL.
  • Hypoglycemia mostly occurs in people with diabetes but can be caused by diabetes medications, hormonal imbalances and excessive alcohol consumption.
  • Actions to take if you or a loved one's blood sugar level gets too low include consuming carbohydrate-rich meals or snacks like juice or honey or taking glucagon injections.
  • Early identification of symptoms and prompt intervention are required to prevent fatal outcomes.

Hypoglycemia is when the body’s blood glucose level is lower than its metabolic needs. Generally, this condition is characterised by a fasting blood sugar level below 70 mg/dL for adults. Glucose is the body’s primary metabolic fuel, and certain organs, like the brain with limited stores, are particularly sensitive to critically low levels of this nutrient. 

In people with diabetes who are using insulin or other antidiabetic medication, hypoglycemia is relatively common. It can also happen in those without diabetes, although less commonly.  Non-diabetic hypoglycemia may be related to drugs, illnesses, tumours, alcohol, and hormonal imbalances

Irrespective of the cause, hypoglycemia can easily become a serious medical emergency if not properly managed. The following sections will teach you how to identify hypoglycemia and the proper steps to manage this condition. 

Causes of low blood glucose levels

Although blood glucose levels typically vary throughout the day, the body tries to prevent any drastic changes. Conditions that alter how the body regulates glucose metabolism, thus leading to hypoglycemia, include:

  1. Antidiabetic medications: Antidiabetic medications are medicines typically taken to correct the excess blood sugar seen in diabetes mellitus. However, they’re also the most common cause of hypoglycemia, especially when you take them without eating food or at a high dosage. Sulfonylureas like tolbutamide and meglitinides like repaglinide are frequent culprits.
  2. Alcohol: Alcohol blocks the body from producing glucose from other noncarbohydrate intermediates. This process is called gluconeogenesis and is responsible for maintaining blood sugar levels even in fasting states. Therefore, hypoglycemia can occur in people who have been drinking excessively without eating.
  3. Tumours: Insulin-secreting tumours of the pancreatic islet cells called insulinomas can result in hypoglycemia. Likewise, other tumours that secrete insulin-like growth factors that force the body to use up more glucose can also cause this condition.
  4. Severe illness: Hypoglycemia may be seen in serious health conditions like end-stage liver disease, kidney failure, starvation, and sepsis. These conditions disrupt the body’s normal glucose regulatory mechanisms.
  5. Hormonal imbalance: The counterregulatory hormones such as cortisol, glucagon, growth hormone (GH), and adrenaline are secreted during hypoglycemia to help the body recover. Disturbances in these hormones, as seen in adrenal insufficiency, can cause hypoglycemia to persist.  

Symptoms of Hypoglycemia

A fasting blood glucose value below 70 mg/dL is the threshold for hypoglycemia, but not everyone experiences symptoms at this point. Some may only begin showing signs of low blood glucose levels when their readings fall below 55 mg/dL, while others show no signs at all. Nevertheless, recognizing these symptoms can help you identify a low blood sugar episode.

Common symptoms of hypoglycemia include:

  • Headaches
  • Hunger
  • Shakiness
  • Sweating
  • Blurry vision
  • Inability to concentrate
  • Tiredness and fatigue
  • Tachycardia (Increased heart rate)
  • Dizziness or lightheadedness 
  • Confusion
  • Irritability
  • Abnormal sensations like tingling lip

In severe cases, hypoglycemia can lead to seizures, loss of consciousness, and even death. 

What to do when your blood sugar levels are low

If you have a glucometer reading of less than 70 mg/dL, you can take the following steps:

  • Boost your blood sugar by eating a carbohydrate-rich meal or snacks like honey, fruits, soda, juice, or glucose tablets.
  • Repeat the blood glucose test in 10–15 minutes. 
  • If your blood sugar level is still below the threshold, take another sugar snack and check again in ten minutes.
  • If your blood glucose level remains low after repeated attempts to correct it, contact your doctor.

For severe hypoglycemia, the individual might be unconscious or unable to swallow. In this case, you can help them recover by doing the following:

  • Put the individual in the recovery position.
  • Give them a glucagon injection.
  • If they improve in ten minutes, you can proceed to give them food to maintain their sugar levels and support them until they fully recover. 
  • If you don’t have a glucagon injection available or the patient fails to recover ten minutes after receiving the glucagon injection, call emergency services.

If you are prone to hypoglycemic episodes, it’s important to inform close family and friends. They should know how to recognize the symptoms of low blood sugar, how to use the glucagon kit, and when to take you to the hospital. 

How to prevent blood sugar levels from getting too low

Here are some tips to help keep your blood sugar levels from getting too low.

1. Follow the prescription of medications

Patients taking medications to reduce their blood sugar levels should follow the dosage strictly. Failure to do so may result in low blood sugar. It’s also important to follow the medication schedule and only take them when due. 

2. Eat well before engaging in physical and mental activities

Intense mental and physical activity uses up glucose stores in the body. Therefore, if you are engaging in such activity, eat a meal or carbohydrate-rich snack before starting. If this will last for a long period, take more carbohydrates in between the activity.

3. Take snacks in between meals

 It is recommended that you take snacks in between meals to keep your glucose levels optimal if they are low.

4. Check your blood glucose regularly

This is essential for patients who have had episodes of hypoglycemia in the past. You need a glucometer (an instrument for measuring blood glucose level) handy for this purpose.

How doctors treat low blood glucose

Low blood glucose can easily become life-threatening, so it requires prompt attention. The goal of any such treatment is to raise blood glucose levels back to normal.

Since 1938, Whipple's triad has been used by doctors in the assessment of hypoglycemia: 

  • First, the doctor identifies the symptoms of hypoglycemia. 
  • The next step is to obtain laboratory evidence of low blood glucose. 
  • The final step is to demonstrate immediate relief of symptoms upon the correction of the low blood glucose.

Severe hypoglycemia (in which the patient is most likely unconscious) is treated with a glucose infusion. On the other hand, conscious patients who can swallow receive the glucose orally, via readily absorbable carbohydrates (such as fruit juice).

For patients who can’t tolerate oral intake, glucagon is administered. Doctors give it intramuscularly (through muscle) or intranasally (through the nose). Glucagon raises blood glucose by stimulating glycogenolysis (the conversion of glycogen into glucose) in the liver.

When the patient becomes conscious, they will need to consume a complex carbohydrate meal to maintain a stable blood glucose level. Thereafter, serial blood glucose checks are done to confirm total recovery.

The health provider then educates the patient on lifestyle changes, early symptoms, and the need to monitor blood glucose levels closely. Wearing a medical alert bracelet may also be a great idea for patients with frequent hypoglycemic episodes.  This is so that anyone around knows what to do to help if hypoglycemia suddenly occurs.

Final thoughts

Hypoglycemia, characterised by low blood glucose levels, can progress to a serious medical emergency if poorly managed. While it may be caused by antidiabetic medication, it may also result from excessive alcohol consumption, underlying medical conditions, tumours, and hormonal imbalances. 

Recognizing symptoms like hunger, lightheadedness, shakiness, blurry vision, and dizziness may help you spot a hypoglycemic episode. However, not everyone experiences these symptoms, so you may need to perform a quick blood sugar test using a glucometer to confirm. 

The goal of treatment is to restore normal blood sugar levels, which can be achieved by consuming a high-sugar meal or snack or by administering a glucagon shot. If the patient fails to improve, they require immediate medical attention. 

Frequently Asked Questions (FAQs)

Does drinking water help with low blood sugar?

Plain water doesn't contain glucose or other calorie sources, so it can’t help improve low blood sugar. Instead, the remedy for a hypoglycemic episode is administering glucose-containing substances through the vein or by mouth.

What helps increase low blood sugar fast? 

Glucose tablets, sugar, honey, soda, juice, and fruits can help raise low blood sugar fast. Doctors may also administer glucose infusions in cases of severe hypoglycemia. 

What range of blood glucose is low?

Blood glucose levels below 70 mg/dL are generally considered to be low.

Can low blood sugar levels cause death?

Yes, severely low blood sugar over a long period causes brain damage, seizures, cardiac arrest, and may finally result in death.


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