Hypoglycemia (low blood sugar) occurs when blood glucose drops below 70 mg/dL. Treat mild-to-moderate lows with the 15-15 rule: 15 grams of fast carbs, wait 15 minutes, recheck. Severe hypoglycemia causing loss of consciousness requires glucagon and emergency care.
Hypoglycemia is one of the most common — and potentially dangerous — complications of diabetes treatment. It occurs when blood glucose falls too low, depriving the brain and body of their primary fuel source. Recognizing the signs early and knowing how to treat it quickly can prevent serious consequences.
Blood Sugar Thresholds
| Level | Value | Action Required |
|---|---|---|
| Level 1 (Alert) | <70 mg/dL | Treat with 15g fast carbs immediately |
| Level 2 (Clinically significant) | <54 mg/dL | Treat urgently; assess why this occurred |
| Level 3 (Severe) | Any level with altered consciousness | Glucagon + call 911 if unresponsive |
Symptoms
Early (mild-moderate): shakiness, sweating, fast heartbeat, hunger, anxiety, dizziness, pale skin, headache, irritability, difficulty concentrating.
Severe: confusion, slurred speech, vision changes, seizure, loss of consciousness. At this stage the person cannot safely self-treat.
⚠️ Hypoglycemia Unawareness: Some people — especially those with long-standing diabetes or frequent lows — lose the ability to feel early warning symptoms. This is called hypoglycemia unawareness and is a serious safety concern. A CGM can help detect lows before symptoms occur.
The 15-15 Rule (Mild-Moderate Lows)
- Consume 15 grams of fast-acting carbohydrates:
- 4 glucose tablets
- 4 oz (½ cup) of fruit juice or regular soda
- 1 tablespoon of honey or sugar
- Glucose gel (1 tube)
- Wait 15 minutes, then recheck blood sugar
- If still below 70 mg/dL, repeat step 1
- Once above 70 mg/dL, eat a small snack containing protein (e.g., crackers with peanut butter) if your next meal is more than an hour away
Do not over-treat — consuming excessive carbs leads to rebound high blood sugar. Stick to 15 grams and wait.
Severe Hypoglycemia & Glucagon
When a person is unconscious, seizing, or unable to swallow safely, glucagon is required. Three options are available:
| Product | Route | How It Works |
|---|---|---|
| Baqsimi | Nasal powder (no injection) | One puff into one nostril — works even if unconscious |
| Gvoke | Auto-injector | Pre-filled, single-click subcutaneous injection |
| Zegalogue | Auto-injector or prefilled syringe | Subcutaneous injection, fast action |
After administering glucagon, place the person on their side (recovery position), call 911 if they don't respond within 15 minutes, and do not give anything by mouth until fully conscious.
Common Causes
- Too much insulin — dose error, incorrect type, wrong timing
- Sulfonylureas (glipizide, glimepiride, glyburide) — these stimulate insulin release regardless of blood sugar level
- Skipping or delaying meals after taking insulin or sulfonylurea
- More physical activity than planned
- Alcohol consumption — especially on an empty stomach; alcohol blocks the liver from releasing glucose
- Hot weather or hot baths — speed insulin absorption
- Illness that reduces food intake but medications remain the same
Nocturnal Hypoglycemia
Lows during sleep are common and dangerous because they often go undetected. Warning signs include waking with headache or wet sheets from sweating, nightmares, and paradoxically high morning blood sugar (Somogyi effect — the liver releases glucose in response to overnight lows). A CGM with alarms is highly effective at detecting and alerting to nocturnal lows.
Prevention
- Never skip meals after taking insulin or sulfonylureas
- Adjust doses before planned exercise — talk to your provider
- Carry glucose tablets or fast carbs at all times
- Wear a medical alert bracelet
- Set CGM low alerts at 70-80 mg/dL
- If frequent lows occur, contact your endocrinologist — medication adjustments are usually needed
Key Takeaways
- Blood sugar below 70 mg/dL is hypoglycemia — treat immediately with 15g fast carbs
- Use the 15-15 rule: treat, wait 15 minutes, recheck, repeat if needed
- Glucagon (Baqsimi, Gvoke, Zegalogue) is required for unconscious or seizing patients — call 911 if no response
- Sulfonylureas and insulin are the medications most likely to cause hypoglycemia
- Hypoglycemia unawareness is a serious risk — CGMs can detect lows before symptoms appear
- Always carry fast-acting carbs and wear a medical alert bracelet
- Frequent lows mean your medication doses likely need adjustment — contact your provider
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