If you have diabetes, ask your doctor whether any of your medicines can make your sugar go low, and agree a plan for lows in advance. What follows is the general guidance published by the American Diabetes Association (ADA) and the US Centers for Disease Control and Prevention (CDC). Your doctor’s plan comes first.
What counts as low
Both the ADA and the CDC treat a blood sugar below 70 mg/dL as low. The CDC calls below 54 mg/dL severe.
Warning signs
Signs differ from person to person and can come on quickly. The CDC lists:
- a fast heartbeat
- shaking
- sweating
- nervousness or anxiety
- irritability or confusion
- dizziness
- hunger
Signs of a more severe low include feeling weak, having trouble walking or seeing clearly, acting strangely or confused, and seizures. Lows can also happen during sleep.
What to do: the 15–15 rule
- If you can, check your sugar.
- If it is below 70 mg/dL, have 15 grams of fast-acting carbohydrate.
- Wait 15 minutes, then check again.
- If it is still below 70 mg/dL, repeat.
- Once it is back up, eat a balanced snack or meal with protein and carbohydrate.
Examples the CDC gives of about 15 grams of fast-acting carbohydrate:
- half a cup (about 120 ml) of fruit juice, or of a regular — not diet — soft drink;
- 1 tablespoon of sugar or honey;
- 3–4 glucose tablets, or one dose of glucose gel.
If your doctor has told you that you are at risk of lows, keep one of these with you.
When it is an emergency
If someone is unconscious, having a seizure, or too drowsy or confused to swallow safely, do not put food or drink in their mouth. Call 112 (or 108 for an ambulance) straight away. Severe lows are treated with glucagon: if the person has been prescribed it and someone with them knows how to give it, it should be given — and medical help is still needed straight afterwards.
Afterwards
Note every low in your log — the time, the reading, what you had eaten and what you were doing — and tell your doctor, even if you managed it yourself. Make sure the people you live with know the signs and what to do.
ⓘThis is general information, not medical advice. Talk to your doctor.
Sources
- American Diabetes Association — “Low Blood Glucose (Hypoglycemia)”
- CDC — “Low Blood Sugar (Hypoglycemia)”
- CDC — “Treatment of Low Blood Sugar (Hypoglycemia)”
Last reviewed 1 October 2026.