Hypoglycemia (Low Blood Sugar)

What is hypoglycemia?

Hypoglycemia is the medical term for low blood sugar or low glucose. Blood sugar or glucose levels can be measured with a blood test. Healthcare providers make the diagnosis of hypoglycemia and recommend treatment when an individual has a blood sugar less than 60 mg/dl (milligrams per deciliter) and experiences symptoms. Some definitions of hypoglycemia use 50 mg/dl. For people with diabetes mellitus, hypoglycemia is diagnosed when the blood sugar is less than 70 mg/dl.

What are the symptoms?

Symptoms of hypoglycemia include:

• Nausea
• Tremors
• Sweating
• Heart palpitations or fluttering
• Confusion
• Weakness
• Hunger

What can cause a low blood sugar to appear on blood test results?

1. Issues with the blood test

An inaccurate blood sugar can be reported if the blood sample is processed too slowly or not refrigerated soon enough after collection. This value is reflective of the lab processing rather than a true measure of the actual blood sugar.

2. Elevated hemoglobin or red blood cell count

Low blood sugar can be seen on a blood test when an individual also has an elevated hemoglobin or red blood cell count level. This is often spurious (not real) because the elevated amount of red blood cells in the blood sample continues to metabolize sugar after the blood is drawn; the measured value is lower than it actually was in the bloodstream. One of the causes for an elevated red blood cell count is sleep apnea, which is more common in people with Down syndrome.

3. Elevated globulins (antibodies)

Low blood sugar can be seen when an individual also has elevated globulins or antibodies. This effect is similar to that with an elevated hemoglobin (described above). People with Down syndrome often have an elevated globulin level for reasons that are not always clear. It is not known if the elevated globulin level in people with Down syndrome is large enough to explain hypoglycemia.

4. Reactive hypoglycemia

This typically occurs within 4 hours after eating. It is more common in those who are obese or overweight and/or have insulin resistance.

5. Fasting hypoglycemia (also referred to as ketotic hypoglycemia)

The blood sugar of some individuals will drop in the morning before eating or at other times when they go several hours without food.

6. Medications

Insulin and some oral medications used to treat diabetes mellitus can cause hypoglycemia. Certain antibiotics and malaria drugs can also cause low blood sugar.

7. Certain tumors

Insulinomas are a type of tumor that secrete insulin. Certain adrenal, pituitary, or pancreatic tumors can also cause low blood sugar.

8. Liver dysfunction

The liver produces and releases glucose. In conditions that affect liver function, such as hepatitis (infection of the liver), the liver does not respond to the demand for more glucose, and hypoglycemia may result.

9. Kidney dysfunction

This can lead to poor metabolism (breakdown) of certain medications. When the medications build up, they cause low blood sugar.

10. Other endocrine disorders

Disorders of the adrenal gland, pituitary gland, or hypothalamus (part of the brain) may cause a low blood sugar.

In our experience, the first five causes most commonly explain hypoglycemia in individuals with Down syndrome. For individuals whose low blood sugar is caused by numbers 1-3, they typically do not have symptoms associated with hypoglycemia and typically do not require treatment for hypoglycemia. However, if a person has symptoms of hypoglycemia and their blood test indicates hypoglycemia, further evaluation is needed. This may include a review of their medications and possibly an evaluation for tumor-related or other endocrine causes of hypoglycemia. The treatment for hypoglycemia will depend on the results of this evaluation.

For conditions 4 and 5, reactive and fasting hypoglycemia, if the person does not have diabetes, treatment considerations include:

• Eat a balanced diet, including lean meat and nonmeat sources of protein, and high-fiber foods, including whole grains, fruits, and vegetables.
• Avoid sugary foods and processed simple carbohydrates, such as white bread or white pasta, especially on an empty stomach.
• If you drink alcohol, eat some food at the same time.
• Eat several small meals and snacks throughout the day, about three hours apart during waking hours.

The Mayo Clinic has more information on treating and preventing reactive hypoglycemia (#4 above) on their website.

Is hypoglycemia more common in people with Down syndrome?

We found one study on ketotic hypoglycemia in people with Down syndrome that did find ketotic hypoglycemia to be more common in children with Down syndrome. Ketotic hypoglycemia is caused by going long periods of time without eating (fasting hypoglycemia) or when ill. The study was done via survey (which has many limitations and potential for error), but it is a first assessment of this problem in people with Down syndrome. More study is needed.