Diabetes

Type 1 Diabetes — Managing Hypoglycaemia

2025-08-30 • Updated 2025-09-14

Type 1 Diabetes — Managing Hypoglycaemia

Hypoglycaemia (low blood sugar) is one of the most common and urgent risks in type 1 diabetes. Fast recognition and treatment prevent harm, and prevention strategies reduce how often lows happen.

🚑 Bottom Line

• Treat immediately if < 3.9 mmol/L (70 mg/dL) or if symptomatic.
• Use the Rule of 15 (15 g fast carbs → recheck in 15 minutes).
• If severe (can’t swallow, seizures, unconscious) → glucagon + call emergency services.

Recognising a Low

• Adrenergic signs: shakiness, sweating, palpitations, anxiety, hunger.
• Neuroglycopenic signs: headache, blurred vision, confusion, irritability, drowsiness.
• Severe: seizures or unconsciousness — requires help from others.

CGM trend arrows can help anticipate drops; confirm with a finger-stick if readings don’t match how you feel.

Immediate Treatment — Rule of 15

1. Take 15–20 g fast-acting carbs
   • e.g., 4 glucose tabs (≈16 g), 150–200 ml juice, glucose gel.
2. Recheck in 15 minutes.
3. If still < 3.9 mmol/L (70 mg/dL), repeat step 1.
4. If the next meal is >1 hour away, add a slow carb (toast, crackers).

Avoid chocolate or high-fat foods for the initial correction — they act too slowly.

Severe Hypoglycaemia

⚠️ If unconscious or unable to swallow:

• A trained person should give glucagon (nasal or injectable).
• Call emergency services immediately.
• Place on the side (recovery position) once breathing is safe.

Common Triggers & Fixes

• Too much bolus / wrong timing: review insulin-to-carb ratio and pre-meal timing.
• Basal too high: patterns at the same time each day may signal a basal adjustment need.
• Exercise (during/after): reduce insulin or add carbs; carry fast carbs at all times.
• Alcohol: eat with drinks; check before bed and overnight.
• Missed/low-carb meals: match bolus to actual carbs; use smaller corrections.

Prevention Strategies

• Set CGM low alerts (and predictive alerts) appropriately; higher overnight if prone to nocturnal lows.
• Use temp basal reductions on pumps around activity; with MDI, reduce bolus or add carbs.
• Rotate injection/infusion sites to avoid unpredictable absorption.
• Keep a hypo kit (glucose + glucagon) at home, work, school, and during exercise.

After a Low

• Record time, activity, insulin, and food leading up to the episode.
• If 2+ lows in a week — or any severe hypo — contact your team to reassess insulin dosing.
• Consider temporary higher glucose targets after clusters of lows.

FAQ

Do I need to eat after I’m back above 3.9 mmol/L?
If your next meal is far away, add a slow carb to prevent another dip.

My CGM says I’m low but I feel fine.
Confirm with a finger-stick; treat if confirmed or if dropping quickly.

Why do I get lows overnight?
Often due to too much basal insulin, evening exercise, or alcohol. Adjust your plan and consider higher overnight CGM alerts.

Further Reading

• American Diabetes Association — Hypoglycaemia
• NHS — Hypoglycaemia
• ISPAD Clinical Practice Consensus Guidelines — Hypoglycaemia (2022)

Related Guides

• Diabetes Emergencies — Hypos, Highs, and Ketones
• Recognising Highs and Lows
• Night-time Hypoglycaemia
• Managing Type 1 Diabetes During Exercise
• Type 1 Diabetes — Sick-Day Management
• Type 1 Diabetes — Guide Hub

Educational only; not a substitute for professional medical advice.

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