In most cases, yes. You usually keep taking your insulin during an illness even if you are not eating, because stopping it can trigger a dangerous problem called diabetic ketoacidosis (DKA). Your dose may need adjustment, so contact your doctor when you get sick.
Important: This article is general information about medication management. It is not medical advice for your specific insulin plan. Always call your doctor or pharmacist when you are sick, because your insulin dose may need to change.
Why This Matters
It feels logical to skip insulin when you cannot eat. With insulin, that logic is backwards and it is risky.
Illness pushes your blood sugar up even when you eat almost nothing. As the CDC explains, "when your body releases hormones to fight the illness, it can also raise your blood sugar levels." So the CDC's plain instruction for sick days is this: "Continue taking your insulin and diabetes pills as usual."
Stopping insulin is also one of the most common ways people end up in the hospital with DKA. The CDC lists the two most common causes of DKA as illness and "missing insulin shots, a clogged insulin pump, or the wrong insulin dose." A sick day combines both triggers, which is why your plan keeps insulin going.
Why Illness Raises Blood Sugar and Ketones Even When You Are Not Eating
When you get sick, your body releases stress hormones like cortisol and glucagon to fight the infection. Those hormones tell your liver to dump extra sugar into your blood and they make your insulin work less well. A review of sick-day medication management puts it simply: during illness, counter-regulatory hormones rise, so "insulin should not be routinely withheld in type 1 or 2 diabetes." Your need for insulin can actually go up while you are sick, not down.
Now add the ketone problem. When there is not enough insulin, your cells cannot pull sugar in for fuel, so your liver burns fat instead. The CDC describes the chain: "your liver breaks down fat for fuel, a process that produces acids called ketones." The MedlinePlus encyclopedia adds that "when ketones are produced too quickly and build up in the blood, they can be toxic by making the blood acidic." That acid buildup is DKA.
So here is the trap. You stop insulin because you are not eating. Your stress hormones keep pushing sugar and ketones up. With no insulin to stop it, the ketones run away and you slide toward DKA. Cutting insulin "because there is no food" is the exact move that sets it off.
That is why insulin gets its own sick-day rules, separate from the pills you might pause.
Your Insulin Sick Day Plan
Here is a practical playbook. It does not replace your doctor's specific instructions, but it covers most sick days.
1. Keep taking your insulin
Do not stop your basal (background) insulin, even if you are not eating. The scoping review of sick-day guidance found the consistent rule across guidelines is to "adjust insulin but never stop." Your mealtime insulin may change because you are eating less, but background insulin keeps ketones away. This is the opposite of some other diabetes pills, which we cover in the table below.
2. Call your doctor about a dose adjustment
Your dose may need to go up or down depending on your blood sugar readings. Never guess at this and never copy a number from the internet. Your prescriber knows your plan, so call or message them early in the illness and ask what to do with your insulin. The general consensus is that insulin is adjusted, not stopped, but the right adjustment is personal to you.
3. Check your blood sugar more often
The CDC suggests you "test your blood sugar every 4 hours and keep track of the results" while sick. More frequent checks help you and your doctor catch a rising trend before it becomes an emergency.
4. Check your ketones
If your blood sugar is high or you feel worse, check for ketones. The CDC notes you "can use an over-the-counter kit to test your urine for ketones." A blood ketone meter works too. Rising ketones are an early warning sign of DKA, so if you see them climbing, call your doctor right away.
5. Sip fluids and small carbs
Even when you cannot face a meal, keep sipping. The CDC advises you "drink plenty of water to prevent dehydration." If your blood sugar is not high, small amounts of regular soda, juice, or broth give your body a little carbohydrate to burn instead of fat, which helps hold ketones down.
6. Know your red flags
Get medical help fast if you have ongoing vomiting, deep or fast breathing, fruity-smelling breath, belly pain that will not stop, confusion, or moderate to large ketones. These can be signs of DKA, which the CDC calls a "serious complication of diabetes that can be life-threatening." When in doubt, call your doctor.
Insulin vs Other Diabetes Meds on Sick Days
This is where insulin stands apart. Some diabetes medicines are paused during a dehydrating illness, but insulin is usually continued. Here is the contrast at a glance.
| Medication | On a sick day | Why |
|---|---|---|
| Insulin | Usually continue, dose may be adjusted by your doctor | Stopping it can trigger DKA |
| SGLT2 inhibitors (like Jardiance) | Hold during vomiting, diarrhea, or low intake | Risk of euglycemic DKA |
| Metformin | Hold during a dehydrating illness | Risk of lactic acidosis |
| Blood pressure pills (ACE / ARB) | Often held during dehydration | Risk to the kidneys when fluids are low |
Notice the pattern. The pills on the hold list are paused because of what they do during dehydration. Insulin is the opposite case: it is the one your body cannot do without while sick. For the full story on the held meds, see our sick-day guides for metformin, Jardiance, and blood pressure medications. When in doubt, insulin belongs on the short list of medications you should never skip without talking to your doctor first.
How Pillo Helps
The hard part of a sick day is not the science. It is that you feel terrible and your routine falls apart. You lose track of time, and the dose you most need to keep, your insulin, is the easy one to forget. That is the gap where ketones build.
Pillo's persistent reminders are built for exactly this. The alarm keeps ringing until you confirm you took your insulin, so a foggy sick day does not become a missed basal dose. You can manage your whole schedule in one place, and if you paused a med like metformin or Jardiance during the illness, Pillo reminds you to restart it once you are better instead of letting it quietly drop off your routine.
Pillo also handles dependents. If you manage insulin for a child, a parent, or a partner, you can track their schedule as a dependent right from your own phone, so their sick-day doses get the same persistent nudge. Pillo does not track blood sugar, so keep using your meter and ketone kit as your doctor directs. Pillo's job is to make sure the dose actually happens.
If you want a reminder that will not let a sick day turn into a missed insulin dose, download Pillo on Google Play.
For more on the choices around forgotten doses, see missed dose of diabetes medication and what to do after vomiting a dose.
Frequently Asked Questions
Should I take insulin if I am not eating?
In most cases, yes. Your background (basal) insulin is usually continued even when you are not eating, because illness raises your blood sugar through stress hormones and stopping insulin can trigger DKA. Your mealtime insulin may change because you are eating less, so call your doctor about how to adjust it. Never stop insulin on your own.
Do you still take insulin when sick and not eating?
Generally yes for basal insulin. The CDC's sick-day guidance is to keep taking your insulin and diabetes pills as usual, check your blood sugar more often, and drink fluids. The dose may need adjustment, which is a conversation for you and your doctor, not a number to guess.
What are the insulin sick day rules?
The core rules are: keep taking your insulin, check your blood sugar more often, check your ketones if your sugar is high or you feel worse, sip fluids and small carbs, and call your doctor about a dose adjustment. Get urgent help for ongoing vomiting, fast breathing, fruity breath, belly pain, confusion, or rising ketones.
Can stopping insulin really cause DKA?
Yes. The CDC names missing insulin and illness as the two most common causes of DKA. Without enough insulin, your liver burns fat into ketones, and those ketones make your blood acidic. A sick day combines illness stress with the temptation to skip insulin, which is a high-risk mix. That is why the plan keeps insulin going.
Why does my blood sugar go up when I am sick even though I am not eating?
Your body releases stress hormones like cortisol and glucagon to fight the illness. As sick-day research describes, these counter-regulatory hormones raise blood sugar and make your insulin less effective, so your need for insulin can rise during illness even with very little food. That is the reason you keep taking it and monitor more closely.
This article provides general information about medication management and is not a substitute for professional medical advice. Always consult your doctor or pharmacist before making changes to your insulin or any other medication, especially when you are sick.
