Sick Day Management - Stay Safe When You're Ill 🤒 - Happy Diabetes
Sick Day Management - Stay Safe When You're Ill 🤒
T1D Fundamentals
The essentials
An Essentials guide gets straight to the point: the key information on the topic, no detours. To go further, check out our full guides.
Learn the essential rules for managing Type 1 Diabetes during illness. Understand why sickness affects blood sugar, when to check ketones, and when to seek emergency help. A vital safety guide every person with T1D should know.
1 learners
What this guide gives you
Why illness makes blood sugar harder to control
The #1 rule: never stop basal insulin
How and when to check ketones
Warning signs that require emergency care
How to prepare a sick day kit
Who is this for?
This guide is for **everyone** with T1D and their caregivers. Whether you're newly diagnosed or have years of experience, these rules can save your life.
Newly diagnosedCaregivers
Sick Day Management - The Essential Guide
Questions about this content?
Alfred can go deeper on any point in this section.
Want to go further?
Explore our full guides on this topic to deepen your knowledge.
Understand why illness raises blood sugar and increases DKA risk
Apply the #1 sick day rule: never stop basal insulin
Know when and how to check blood ketones
Recognize warning signs that require emergency care
Prepare a sick day kit before you need it
Warning
This guide covers vital safety information. It does not replace your healthcare team's advice. If you're currently sick and unsure what to do, call your doctor or diabetes educator now.
Why does illness affect blood sugar?
When you're sick — whether it's a cold, flu, stomach bug, infection, or even a dental procedure — your body goes into "fight mode." It releases stress hormones like cortisol, adrenaline, and glucagon. These hormones have one job: give your body more energy to fight the illness.
The problem? They do this by pushing more glucose into your blood and making your cells more resistant to insulin.
The result: your blood sugar rises, even if you're eating less or not eating at all.
Info
This is why many people with T1D are shocked to see blood sugars of 300+ mg/dL (16+ mmol/L) during a simple cold — even when they haven't eaten. It's not something you did wrong. It's your body's stress response.
The DKA danger
Without enough insulin to handle this extra glucose, your body starts burning fat for energy instead. This produces ketones — acidic byproducts that build up in your blood. When ketones accumulate too much, you develop diabetic ketoacidosis (DKA), a life-threatening emergency.
DKA can develop in just a few hours during illness. That's why sick day management is a matter of safety, not just comfort.
Quick Check: Illness & Blood Sugar
1 / 3
Why does blood sugar typically rise when you are sick, even if you are eating less than usual?
The golden rules of sick days
Rule #1: NEVER stop your basal insulin
This is the most important rule. Even if you can't eat, even if your blood sugar seems "OK" — keep taking your basal insulin (long-acting injection or pump basal rate).
Without basal insulin, DKA can develop within hours, regardless of what you eat.
Warning
Stopping basal insulin during illness is the #1 cause of preventable DKA. Your body needs MORE insulin when sick, not less.
Rule #2: Check blood sugar every 2-4 hours
During illness, your blood sugar can change rapidly. Set alarms if needed. If you use a CGM, keep a close eye on trends and arrows.
Rule #3: Check ketones if blood sugar is above 250 mg/dL (14 mmol/L)
Use a blood ketone meter (more accurate than urine strips). Here's what the numbers mean:
Blood ketones
What it means
What to do
< 0.6 mmol/L
Normal
Continue monitoring
0.6 - 1.5 mmol/L
Slightly elevated
Extra correction dose, drink water, recheck in 1-2h
1.5 - 3.0 mmol/L
Risk of DKA
Call your healthcare team immediately
> 3.0 mmol/L
High DKA risk
Rule #4: Stay hydrated
Dehydration makes everything worse. Aim for at least 250 mL of fluid per hour while awake.
You may need more correction doses during illness. Follow your healthcare team's sick day plan. If you don't have one yet, ask for one at your next appointment.
Tip
For pump users: consider setting a temporary basal rate increase of 10-20% during illness. For MDI users: your doctor may advise additional correction doses every 4-6 hours.
The stomach bug: a special case
Gastroenteritis (vomiting and diarrhea) is especially tricky because:
You can't keep food or fluids down → risk of hypoglycemia
But stress hormones still push blood sugar UP → risk of hyperglycemia
Dehydration happens fast → accelerates DKA risk
Key strategies:
Take small, frequent sips instead of large amounts
Try ice chips, popsicles, or small sips of flat ginger ale
Check blood sugar every 1-2 hours (more frequently than other illnesses)
If you can't keep any fluids down for more than 2 hours, call your doctor
Warning
If you are vomiting repeatedly AND have ketones above 1.5 mmol/L, go to the emergency room. You likely need IV fluids and insulin.
When to call for help
Call your healthcare team if:
Blood sugar stays above 250 mg/dL (14 mmol/L) for more than 4 hours despite corrections
Ketones are between 1.5 and 3.0 mmol/L
You can't keep fluids down for more than 2 hours
You have a fever that won't respond to medication
You're unsure about insulin dosing
Go to the emergency room if:
Ketones are above 3.0 mmol/L
You are vomiting repeatedly and can't keep anything down
You feel confused, drowsy, or have trouble breathing
You have rapid, deep breathing (Kussmaul breathing)
You have severe abdominal pain
Info
When in doubt, err on the side of caution. It's always better to call and ask than to wait too long. DKA is treatable — but only if you act quickly.
Your sick day kit
Don't wait until you're sick to gather supplies. Prepare this kit now and keep it accessible:
Essential items:
Blood ketone meter + extra strips (check expiry dates regularly)
