| Testing frequency | Every 2β4 hours when unwell |
| Ketone threshold (action) | Above 0.6 mmol/L |
| Emergency ketone level | Above 1.5 mmol/L |
| Fluid intake target | 100β200 mL per hour |
| High glucose threshold | 14 mmol/L (252 mg/dL) β check ketones |
Key Takeaways
- Check blood glucose every 2β4 hours when unwell
- Never stop insulin without medical advice, even if not eating
- Check ketones if blood glucose exceeds 14 mmol/L (252 mg/dL)
- Maintain fluid intake to prevent dehydration and DKA
- Know the warning signs requiring emergency hospital care
What Are Sick Day Rules?
Sick day rules are a set of evidence-based guidelines helping people with diabetes manage their condition safely during illness. When you are unwell, stress hormones such as cortisol and adrenaline cause blood glucose to rise β even if you are eating less than normal. Following a structured sick day plan prevents dangerous complications including diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS).
Monitoring During Illness
Blood Glucose Testing
Increase your testing frequency to every 2β4 hours. Record all results carefully. Both Type 1 and Type 2 diabetes can produce dangerously high or low readings during illness.
Ketone Testing
People with Type 1 diabetes (and some with Type 2) should test for ketones whenever blood glucose exceeds 14 mmol/L or 252 mg/dL. Blood ketone meters provide faster, more accurate results than urine strips. MDS Diabetes stocks a range of blood ketone meters and testing strips for home use.
| Ketone Level | Action |
|---|---|
| Below 0.6 mmol/L | Normal β continue monitoring |
| 0.6β1.5 mmol/L | Caution β contact your diabetes team |
| Above 1.5 mmol/L | Danger β seek urgent medical care |
Medication Management
Insulin Users
Never stop taking insulin during illness. Your body needs insulin to process glucose even when you are not eating. Your diabetes team may provide a sick day insulin adjustment plan β follow it precisely. If you use an insulin pump, contact your team if you are vomiting or unable to manage the device.
Type 2 Medications
Some oral medications should be paused when unwell. The SADMAN rule helps identify which drugs to stop temporarily:
- S β SGLT2 inhibitors (e.g. empagliflozin, dapagliflozin)
- A β ACE inhibitors
- D β Diuretics
- M β Metformin (if vomiting or dehydrated)
- A β ARBs (angiotensin receptor blockers)
- N β NSAIDs (e.g. ibuprofen)
Always confirm with your GP or diabetes nurse before stopping any medication.
Hydration and Nutrition
Aim for at least 100β200 mL of fluid every hour. If you cannot eat normally, replace meals with easily digestible carbohydrates such as crackers, soup, or fruit juice in small amounts to prevent hypoglycaemia in insulin users. Avoid sugary sports drinks as your primary fluid if glucose is already elevated.
When to Call for Help
Seek urgent medical advice or call emergency services if you experience any of the following:
- Blood ketones above 1.5 mmol/L or large urinary ketones
- Persistent vomiting preventing fluid intake
- Blood glucose above 20 mmol/L (360 mg/dL) unresponsive to correction
- Confusion, drowsiness, or difficulty breathing
- Illness lasting more than 24β48 hours without improvement
Building a Sick Day Kit
Prepare in advance. Your sick day kit should include your glucose meter and spare lancets, ketone testing supplies, fast-acting glucose tablets or gel, a thermometer, contact numbers for your diabetes team, and a written copy of your sick day plan. MDS Diabetes offers complete diabetes management bundles with everything needed for sick day preparedness.