Low Blood Sugar (Hypoglycemia): Symptoms, Causes and What to Do

What it involves

MedlinePlus defines low blood sugar, or hypoglycemia, as a drop in blood glucose that is too low, with a reading below 70 mg/dL considered low. At or below that level it can be harmful. It most often affects people with diabetes who take insulin or certain other diabetes medicines.

Who this is for

• Patients with diabetes who have had shaky, sweaty, or confused spells and want their treatment reviewed
• Patients without diabetes who have repeated episodes of shakiness, hunger, and sweating
• Patients who feel low blood sugar less than they used to, or not at all, and want to be safer
• Family members who want to know what to do when someone seems to be having a low

What to expect

• Questions about when episodes happen, how they feel, what you ate, and your medicines
• A review of your glucose readings, meter, or monitor if you have one
• A discussion of timing of meals, medicines, alcohol, and activity
• A plan that may include medicine changes, blood work, or a referral if a less common cause is suspected

What it can feel like

MedlinePlus lists a wide range of symptoms, and not everyone feels a low in the same way. Mild ones, such as hunger and sweating, can occur when blood sugar is only slightly low:

• Shaking, trembling, a fast or pounding heartbeat, and nervousness
• Hunger, sweating, headache, and tiredness or weakness
• Blurry or double vision and tingling or numbness of the skin
• Feeling cranky or acting aggressive, and unclear thinking
• Seizures when blood sugar drops much lower, under about 54 mg/dL

Why it happens in people with diabetes

MedlinePlus says low blood sugar can happen when too much insulin is in the blood, when the body uses up glucose too fast, or when glucose is released too slowly. It can occur in people who take insulin or certain other diabetes medicines, and exercise can bring on a low in someone taking insulin, though many diabetes medicines do not cause lows. The diabetes management page describes ongoing care.

Causes in people without diabetes

MedlinePlus lists drinking alcohol, a rare pancreatic tumor that makes too much insulin, lack of hormones such as cortisol or thyroid hormone, severe heart, kidney, or liver failure, whole-body infection, some weight-loss surgeries years afterward, and certain medicines not used for diabetes. The thyroid care page explains thyroid follow-up, and the kidney function tests guide explains kidney numbers.

Treating a low

MedlinePlus says treatment aims to raise the blood sugar and then to find out why it dropped. For people with diabetes it lists a sugary drink such as juice, food, glucose tablets, or a glucagon shot if a provider has taught that. If signs do not improve after a sugary snack, it says to get a ride to the emergency room and not to drive yourself.

When it is an emergency

Severe low blood sugar is a medical emergency, according to MedlinePlus, and can lead to seizures and brain damage. It says to get medical help right away for a person who becomes less alert or cannot be woken, and to call 911. One severe episode can make the next one harder to recognize, which is called hypoglycemic unawareness.

Watching for patterns

MedlinePlus says a continuous glucose monitor worn for several days can reveal lows that go unnoticed, and that people with diabetes should ask whether one would help. A related pattern is dizziness, covered in the dizziness guide, and tiredness, covered in the fatigue guide.

Sources

• MedlinePlus — Low blood sugar
• MedlinePlus — Hypoglycemia health topic