Low blood sugar can cause uncomfortable symptoms, such as dizziness and confusion, and can quickly become serious if left untreated.
Hypoglycemia is a condition in which your blood sugar (glucose) level is lower than the standard range. Glucose is your body's main energy source.
Hypoglycemia is often related to diabetes treatment. But other drugs and a variety of conditions — many rare — can cause low blood sugar in people who don't have diabetes.
Hypoglycemia needs immediate treatment. For many people, a fasting blood sugar of 70 milligrams per deciliter (mg/dL), or 3.9 millimoles per liter (mmol/L), or below should serve as an alert for hypoglycemia. But your numbers might be different. Ask your health care provider.
Treatment involves quickly getting your blood sugar back to within the standard range either with a high-sugar food or drink or with medication. Long-term treatment requires identifying and treating the cause of hypoglycemia.
If blood sugar levels become too low, hypoglycemia signs and symptoms can include:
As hypoglycemia worsens, signs and symptoms can include:
Severe hypoglycemia may cause:
Seek medical help immediately if:
Seek emergency help for someone with diabetes or a history of hypoglycemia who has symptoms of severe hypoglycemia or loses consciousness.
Hypoglycemia occurs when your blood sugar (glucose) level falls too low for bodily functions to continue. There are several reasons why this can happen. The most common reason for low blood sugar is a side effect of medications used to treat diabetes.
When you eat, your body breaks down foods into glucose. Glucose, the main energy source for your body, enters the cells with the help of insulin — a hormone produced by your pancreas. Insulin allows the glucose to enter the cells and provide the fuel your cells need. Extra glucose is stored in your liver and muscles in the form of glycogen.
When you haven't eaten for several hours and your blood sugar level drops, you will stop producing insulin. Another hormone from your pancreas called glucagon signals your liver to break down the stored glycogen and release glucose into your bloodstream. This keeps your blood sugar within a standard range until you eat again.
Your body also has the ability to make glucose. This process occurs mainly in your liver, but also in your kidneys. With prolonged fasting, the body can break down fat stores and use products of fat breakdown as an alternative fuel.
If you have diabetes, you might not make insulin (type 1 diabetes) or you might be less responsive to it (type 2 diabetes). As a result, glucose builds up in the bloodstream and can reach dangerously high levels. To correct this problem, you might take insulin or other medications to lower blood sugar levels.
But too much insulin or other diabetes medications may cause your blood sugar level to drop too much, causing hypoglycemia. Hypoglycemia can also occur if you eat less than usual after taking your regular dose of diabetes medication, or if you exercise more than you typically do.
Hypoglycemia in people without diabetes is much less common. Causes can include:
Hypoglycemia usually occurs when you haven't eaten, but not always. Sometimes hypoglycemia symptoms occur after certain meals, but exactly why this happens is uncertain.
This type of hypoglycemia, called reactive hypoglycemia or postprandial hypoglycemia, can occur in people who have had surgeries that interfere with the usual function of the stomach. The surgery most commonly associated with this is stomach bypass surgery, but it can also occur in people who have had other surgeries.
Untreated hypoglycemia can lead to:
Hypoglycemia can also cause:
Over time, repeated episodes of hypoglycemia can lead to hypoglycemia unawareness. The body and brain no longer produce signs and symptoms that warn of a low blood sugar, such as shakiness or irregular heartbeats (palpitations). When this happens, the risk of severe, life-threatening hypoglycemia increases.
If you have diabetes, recurring episodes of hypoglycemia and hypoglycemia unawareness, your health care provider might modify your treatment, raise your blood sugar level goals and recommend blood glucose awareness training.
A continuous glucose monitor (CGM) is an option for some people with hypoglycemia unawareness. The device can alert you when your blood sugar is too low.
If you have diabetes, episodes of low blood sugar are uncomfortable and can be frightening. Fear of hypoglycemia can cause you to take less insulin to ensure that your blood sugar level doesn't go too low. This can lead to uncontrolled diabetes. Talk to your health care provider about your fear, and don't change your diabetes medication dose without discussing changes with your health care provider.
Follow the diabetes management plan you and your health care provider have developed. If you're taking new medications, changing your eating or medication schedules, or adding new exercise, talk to your health care provider about how these changes might affect your diabetes management and your risk of low blood sugar.
Learn the signs and symptoms you experience with low blood sugar. This can help you identify and treat hypoglycemia before it gets too low. Frequently checking your blood sugar level lets you know when your blood sugar is getting low.
A continuous glucose monitor (CGM) is a good option for some people. A CGM has a tiny wire that's inserted under the skin that can send blood glucose readings to a receiver. If blood sugar levels are dropping too low, some CGM models will alert you with an alarm.
Some insulin pumps are now integrated with CGMs and can shut off insulin delivery when blood sugar levels are dropping too quickly to help prevent hypoglycemia.
Be sure to always have a fast-acting carbohydrate with you, such as juice, hard candy or glucose tablets so that you can treat a falling blood sugar level before it dips dangerously low.
For recurring episodes of hypoglycemia, eating frequent small meals throughout the day is a stopgap measure to help prevent blood sugar levels from getting too low. However, this approach isn't advised as a long-term strategy. Work with your health care provider to identify and treat the cause of hypoglycemia.
A continuous glucose monitor, on the left, is a device that measures blood sugar every few minutes using a sensor inserted under the skin. An insulin pump, attached to the pocket, is a device that’s worn outside of the body with a tube that connects the reservoir of insulin to a catheter inserted under the skin of the abdomen. Insulin pumps are programmed to deliver specific amounts of insulin continuously and with food.
If you have hypoglycemia symptoms, your health care provider will likely conduct a physical exam and review your medical history.
If you use insulin or another diabetes medication to lower your blood sugar, and you have signs and symptoms of hypoglycemia, test your blood sugar levels with a blood glucose meter. If the result shows low blood sugar (under 70 mg/dL), treat according to your diabetes treatment plan.
Keep a record of your blood sugar testing results and how you treated low blood sugar levels so that your health care provider can review the information to help adjust your diabetes treatment plan.
If you don't use medications known to cause hypoglycemia, your health care provider will want to know:
If you have hypoglycemia symptoms, do the following:
Hypoglycemia is considered severe if you need help from someone to recover. For example, if you can't eat, you might need a glucagon injection or intravenous glucose.
In general, people with diabetes who are treated with insulin should have a glucagon kit for emergencies. Family and friends need to know where to find the kit and how to use it in case of emergency.
If you're helping someone who is unconscious, don't try to give the person food or drink. If there's no glucagon kit available or you don't know how to use it, call for emergency medical help.
Preventing recurrent hypoglycemia requires your health care provider to identify the condition causing hypoglycemia and treat it. Depending on the cause, treatment may involve:
If you have diabetes and you're having repeated episodes of hypoglycemia, or if your blood sugar levels are dropping significantly, talk with your health care provider to find out how you might need to change your diabetes treatment plan.
If you haven't been diagnosed with diabetes, make an appointment with your primary care provider to determine the cause of your hypoglycemia and appropriate treatment.
Here's some information to help you get ready for your appointment. Take a family member or friend along, if possible. Someone who accompanies you can help you remember the information you're given.
Before your appointment:
Questions to ask your health care provider if you have diabetes include:
Questions to ask your health care provider if you haven't been diagnosed with diabetes include:
Your health care provider might ask you questions, including:
Your health care provider will ask additional questions based on your responses, symptoms and needs. Preparing and anticipating questions will help you make the most of your appointment time.