Tracking and Preventing Nighttime Lows (Nocturnal Hypoglycemia)
Overnight glucose drops are dangerous and often go unnoticed
Nocturnal hypoglycemia occurs when blood glucose drops below 70 mg/dL while sleeping. It frequently causes night sweats, nightmares, morning headaches, or sudden mid-sleep awakenings.
💡 Why it matters: Unnoticed nocturnal lows can trigger dangerous rebound morning spikes (Somogyi effect) or blunt your awareness of daytime hypoglycemia.
How to Track Overnight Glucose
1
Check glucose at bedtime
💡 Ensure bedtime reading is at or above 100-110 mg/dL before sleeping
2
Set a 3:00 AM alarm for 3 consecutive nights
💡 This is when the physiological nadir typically occurs
3
Log bedtime snacks and evening alcohol
💡 Alcohol inhibits hepatic gluconeogenesis and causes delayed lows
4
Note intense late-afternoon exercise
💡 Muscle glycogen repletion can pull glucose for up to 12 hours post-workout
Overnight Patterns to Recognize
Low at 3 AM and high at 7 AM
→ Likely Somogyi rebound — check with doctor about reducing nighttime basal insulin or sulfonylureas
Normal at 3 AM but high at 7 AM
→ Dawn phenomenon (hormonal surge) — requires morning insulin timing adjustment
Waking with night sweats and palpitations
→ Test immediately; keep 15g fast-acting carbs on nightstand
Drops below 70 mg/dL after evening drinks
→ Always pair alcohol with a balanced complex carb and protein snack
Expert Tips
- ★Keep glucose tabs, juice box, or dex4 right at your bedside table
- ★A small bedtime snack with complex carbs and protein (e.g., peanut butter on whole wheat) stabilizes overnight levels
- ★If using a continuous glucose monitor (CGM), set urgent low alarms at 70 mg/dL
- ★Review your evening insulin or medication dose with your endocrinologist if drops occur more than once a week