Low Blood Sugar Symptoms and Ranges

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Foods to Eat and Foods to Avoid with Type 2 Diabetes

If you have type 1 or type 2 diabetes your doctor most likely has recommended dietary changes to manage your blood sugar levels. Simple carbohydrates or simple "carbs" are the primary culprit in raising blood sugar levels in people with diabetes. "Glycemic index" and "glycemic load" are terms used to measure the impact some foods have on your blood sugar levels. Low glycemic foods, for example complex carbohydrates like brown rice, quinoa, steal cut oatmeal, vegetables, some fruits (sugar is a high glycemic food), beans, and lentils don't raise blood sugar levels very much. However, high glycemic foods (simple carbs); for example, sugar, white flour and bread, cookies, pastries, and white potatoes; can raise blood sugar levels dangerously high.

Quick GuideBlood Sugar Swings: Tips for Managing Diabetes & Glucose Levels

Blood Sugar Swings: Tips for Managing Diabetes & Glucose Levels

Low blood sugar (hypoglycemia) definition and facts

  • Hypoglycemia is the medical term for low blood sugar. It typically occurs as a side effect of medications for diabetes.
  • The normal range of blood glucose is from 70 to 100 mg/dL in an individual without diabetes,
  • Most people will feel the effects and symptoms of low blood sugar when blood glucose levels are lower than 50 mg/dL.
  • Symptoms and signs include nervousness, dizziness, trembling, sweating, hunger, weakness, and palpitations.
  • Severe cases may lead to seizures and loss of consciousness.
  • Low blood sugar is treated by giving a readily absorbed source of sugar, including soft drinks, juice, or foods containing sugar.
  • If the hypoglycemia has progressed to the point at which the patient cannot take anything by mouth, an injection of glucagon may be given. Glucagon is a hormone that causes a fast release of glucose from the liver.

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.

Who gets low blood sugar?

Risk factors are having type 1 or 2 diabetes or in some cases, prediabetes.

What can cause 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.

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.

Medically Reviewed by a Doctor on 2/24/2017

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