Hypoglycemia: Common Questions Answered
Hypoglycemia: straight answers to the questions people actually ask, with the figures behind them.
Blood glucose falling too low, usually in people taking insulin or sulfonylureas.
Key takeaways
- Commonly defined as: below 70 mg/dL
- Early symptoms: shakiness, sweating, hunger, anxiety, fast heartbeat
- Most useful single change: Carry fast-acting carbohydrate, such as glucose tablets or juice, at all times.
- Commonest mistake: Driving when your glucose is low or you feel any symptoms.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
What is Hypoglycemia?
Blood glucose falling too low, usually in people taking insulin or sulfonylureas.
Why does it matter?
It can develop quickly, impairs judgment exactly when judgment is needed, and is dangerous while driving.
Commonly defined as for Hypoglycemia?
Below 70 mg/dL.
Early symptoms for Hypoglycemia?
Shakiness, sweating, hunger, anxiety, fast heartbeat.
Immediate treatment for Hypoglycemia?
15 g of fast-acting carbohydrate (the 15-15 rule).
Recheck after for Hypoglycemia?
15 minutes, and repeat if still below 70 mg/dL.
What is the single most useful thing to do?
Carry fast-acting carbohydrate, such as glucose tablets or juice, at all times.
What is the most common mistake?
Driving when your glucose is low or you feel any symptoms.
When should I see a doctor?
Call 911 if someone with diabetes becomes unconscious, has a seizure, or cannot swallow safely — give glucagon if it is available, but do not put food or drink in their mouth. See your doctor about repeated episodes, loss of the early warning symptoms, or episodes overnight.
More questions, answered
Why not treat a low with chocolate?
Chocolate and other high-fat foods slow digestion, so the sugar reaches your blood more slowly. When you are low, you want glucose to rise quickly. Glucose tablets, juice or regular soda work faster. Save fat- and protein-containing snacks for after your glucose is back in range.
Can I have a low while asleep?
Yes. Overnight lows are common in people on insulin, especially after exercise or alcohol. Signs include nightmares, waking sweaty, a morning headache or feeling hungover. Checking glucose at bedtime, a sensor with alarms and treatment adjustments can reduce the risk.
Is it safe to exercise if I take insulin?
Yes, and exercise is valuable. Check glucose before, during longer sessions, and after. You may need extra carbohydrate or a lower insulin dose, and lows can occur hours later. Your care team can help you build a plan for the types of activity you do.
Can people without diabetes have low blood sugar?
It is uncommon, but it can happen, for example after some types of stomach surgery, with certain medicines, heavy drinking, or rare hormone or tumor conditions. Feeling shaky when hungry is usually not true hypoglycemia. If you have repeated symptoms, see your doctor for proper testing.
What if I cannot check my glucose?
If you have symptoms of a low and cannot check, treat it anyway with fast-acting carbohydrate. Treating a possible low is much safer than waiting. Check as soon as you can afterward and mention the episode to your care team.
Does alcohol cause lows?
It can, especially in people on insulin or sulfonylureas. Alcohol interferes with the liver releasing glucose, and the effect can last many hours. Eat when you drink, check glucose before bed and be aware that the symptoms of a low can be mistaken for drunkenness.
Related topics
- What the Guidance Really Says About Medicines and Driving (Medicines Safety)
- Gestational Diabetes: Sorting the Evidence From the Noise (Pregnancy and Postpartum)
- Acute Kidney Injury: What the Evidence Actually Says (Kidney Health)
- What the Guidance Really Says About Sick Day Rules (Long-Term Conditions)
Where to go next
- Popular Beliefs About Hypoglycemia, and What Is Actually Published
- Starting Out With Hypoglycemia
- Hypoglycemia — the reference entry
- Diabetes: The Complete Guide
- Diabetic Eye Screening: Sorting the Evidence From the Noise
- Carbohydrates and Blood Glucose: Sorting the Evidence From the Noise
When to speak to a doctor
Call 911 if someone with diabetes becomes unconscious, has a seizure, or cannot swallow safely — give glucagon if it is available, but do not put food or drink in their mouth. See your doctor about repeated episodes, loss of the early warning symptoms, or episodes overnight.
Where this comes from
- National Institute of Diabetes and Digestive and Kidney Diseases — Low Blood Glucose (Hypoglycemia)
- American Diabetes Association — Standards of Care in Diabetes
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
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