Low blood sugar (hypoglycemia)
Low blood sugar occurs when there is not enough sugar in the blood.
What is low blood sugar?
Hypoglycemia or low blood sugar is syndrome that results from low blood sugar. The severity and symptoms of hypoglycemia can vary from person to person. Blood tests can diagnose low blood sugar, and symptoms resolve when the levels of sugar in the blood return to the normal range. The medical term for blood sugar is blood glucose.
What are the symptoms and signs that your blood sugar is too low?
The normal range of glucose in the bloodstream is from 70 to 100 mg/dL when the individual is fasting (that is not immediately after a meal). The body’s biochemical response to hypoglycemia usually starts when sugars are in the high/mid 70’s. At this point, the liver releases its stores and the hormones mentioned above start to activate. In many people, this process occurs without any clinical symptoms. The amount of insulin produced also declines in an attempt to prevent a further drop in glucose.
While there is some degree of variability among people, most will usually develop symptoms suggestive of low blood sugar when blood glucose levels are lower than 50 mg/dL. The first set of symptoms are called adrenergic (or sympathetic) because they relate to the nervous system’s response to hypoglycemia. People with hypoglycemia may experience any of these symptoms and signs:
- Intense hunger.
- Dizzy or lightheaded.
- Often have trouble speaking.
- Trouble concentrating.
- irritable and nervous.
- Changes in behavior or personality.
In most people, these symptoms are easily recognizable. The vast majority of individuals with diabetes only experience this degree of hypoglycemia if they are on medications or insulin. People (with diabetes or who have insulin resistance) with high circulating levels of insulin who fast or change their diet to lower their carbohydrate intake drastically should also be cautioned. These individuals may also experience modest hypoglycemia.
People being treated for diabetes who experience the condition may not experience symptoms as easily as people without diabetes. This phenomenon has been referred to as hypoglycemic unawareness. This can be dangerous as blood sugars may approach extremely low levels before any symptoms are perceived.
Anyone who has experienced an episode of hypoglycemia describes a sense of urgency to eat and resolve the symptoms. And, that’s exactly the point of these symptoms. They act as warning signs to tell the body to consume more fuel. At this level, the brain still can access circulating blood glucose for fuel. The symptoms provide a person the opportunity to raise blood glucose levels before the brain is affected.
If a person does not or cannot respond by eating something to raise blood glucose, the levels of glucose continue to drop. With further drops in blood glucose, patients progress to neuro-glyco-penic ranges (meaning that the brain is not getting enough glucose). At this point, symptoms progress to confusion, drowsiness, changes in behavior, coma, and seizure.
Why is low blood sugar dangerous?
When the circulating level of blood glucose falls, the brain actually senses the drop. The brain then sends out messages that trigger a series of events, including changes in hormone and nervous system responses that are aimed at increasing blood glucose levels. Insulin secretion decreases and hormones that promote higher blood glucose levels, such as glucagon, cortisol, growth hormone, and epinephrine all increase. As mentioned previously, there is a store in the liver of glycogen that can be converted to glucose rapidly.
In addition to the biochemical processes that occur, the body starts to consciously alert the affected person that it needs food by causing the signs and symptoms of hypoglycemia.
The body needs fuel to work. One of its major fuel sources is sugars, which the body gets from what is consumed as either simple sugar or complex carbohydrates in the diet. For emergency situations (like prolonged fasting), the body stores a stash of sugar in the liver as glycogen. If this store is needed, the body goes through a biochemical process to make new sugar (gluco-neo-genesis) and converts these stores of glycogen to sugar. This backup process emphasizes that the fuel source of sugar is important (important enough for human beings to have developed an evolutionary system of storage to avoid a sugar deficit).
Of all the organs in the body, the brain depends on sugar (glucose) almost exclusively. Rarely, if absolutely necessary, the brain will use ketones as a fuel source, but this is not preferred. The brain cannot make its own glucose and is 100% dependent on the rest of the body for its supply. If for some reason, the glucose level in the blood falls (or if the brain’s requirements increase and demands are not met) there can be effects on the function of the brain.
Despite advances in the treatment of diabetes, low blood sugar episodes often are the limiting factor in achieving optimal blood sugar control, because many medications that are effective in treating diabetes carry the risk of lowering the blood sugar level too much, causing symptoms of the condition. In large scale studies looking at tight control in both type 1 and type 2 diabetes, low blood sugars occurred more often in the patients who were managed most intensively. This is important for patients and physicians to recognize, especially as the goal for treating patients with diabetes becomes tighter control of blood sugar.
What causes low blood sugar?
Despite advances in the treatment of diabetes, low blood sugar episodes occur as a side effect of many treatments for diabetes. In fact, these episodes are often the limiting factor in achieving optimal blood sugar control, because many medications that are effective in treating diabetes carry the risk of lowering the blood sugar level too much, causing symptoms. In large scale studies looking at tight control in both type 1 and type 2 diabetes, low blood sugars occurred more often in the patients who were managed most intensively. This is important for patients and physicians to recognize, especially as the goal for treating patients with diabetes becomes tighter control of blood sugar.
While people who do not have any metabolic problems can complain of symptoms that resemble low blood sugar, true hypoglycemia usually occurs in people with diabetes mellitus (type 1 and type 2). People with pre-diabetes or insulin resistance also can have low blood sugars on occasion if their high circulating insulin levels are further challenged by a prolonged period of fasting. There are other rare causes for the condition, such as insulin-producing tumors (insulinomas) and certain medications.
These uncommon causes of hypoglycemia will not be discussed in this article, which will primarily focus on the condition occurring with type 1 or 2 diabetes and its treatment.
What drinks and foods raise blood sugar fast?
The acute management of low blood sugar involves the rapid delivery of a source of easily absorbed sugar. Regular soft drinks, juice, lifesaver candies, table sugar, and the like are good options. In general, 15 grams of glucose is the dose that is given, followed by an assessment of symptoms and a blood glucose check if possible. If after 10 minutes there is no improvement, another 10-15 grams should be given. This can be repeated up to three times. At that point, the patient should be considered as not responding to the therapy and an ambulance should be called.
The equivalency of 10-15 grams of glucose (approximate servings) are:
- Four lifesavers
- 4 teaspoons of sugar
- 1/2 can of regular soda or juice
Many people like the idea of treating low blood sugar with dietary treats such as cake, cookies, and brownies. However, sugar in the form of complex carbohydrates or sugar combined with fat and protein are much too slowly absorbed to be useful in acute treatment.
Once the acute episode has been treated, a healthy, long-acting carbohydrate to maintain blood sugars in the appropriate range should be consumed. Half a sandwich is a reasonable option.
If the hypoglycemic episode has progressed to the point at which the patient cannot or will not take anything by mouth, more drastic measures will be needed. In many cases, a family member or roommate can be trained in the use of glucagon. Glucagon is a hormone that causes a rapid release of glucose stores from the liver. It is an injection given intramuscularly to an individual who cannot take glucose by mouth. A response is usually seen in minutes and lasts for about 90 minutes. Again, a long-acting source of glucose should thereafter be consumed to maintain blood sugar levels in the safe range. If glucagon is not available and the patient is not able to take anything by mouth, emergency services (for example 911) should be called immediately. An intravenous route of glucose administration should be established as soon as possible.
With a history of recurrent hypoglycemic episodes, the first step in treatment is to assess whether it is related to medications or insulin treatment. Patients with a consistent pattern of the condition may benefit from a medication dose adjustment. It is important that people with diabetes who experience low blood sugar to check blood glucose values multiple times a day to help define whether there is a pattern related to meals or medications. Some people who experience recurrent episodes will benefit from changes in when and what they eat, for example, eating multiple small meals and frequent small snacks throughout the day rather than three larger meals.
What else can you do to control blood sugar levels?
Yes. People with diabetes should wear identification stating they have diabetes and whether they have recurrent low blood sugar. Those at risk for the health condition should be counseled on checking blood sugars before they drive a car, operate heavy machinery, or do anything physically taxing. In addition, it is important to carry a quick-acting glucose source (such as those mentioned above) at all times, and keep a source in their car, office, and by their bedside. Efforts should be made to minimize the hypoglycemic effects of drug regimens and to avoid variable surges in exercise, activity, and drinking alcohol.
Medically Reviewed on 9/9/2019
Hypoglycemia. Medscape. Updated: Jul 25, 2019.