When youâre sick, your body doesnât just want rest-it wants insulin. For people with diabetes, especially Type 1, getting sick isnât just about feeling bad. Itâs a medical event that can quickly turn dangerous if you donât know what to do. Fever, vomiting, or even a bad cold can spike your blood sugar, flood your system with ketones, and push you toward diabetic ketoacidosis (DKA)-a life-threatening condition that sends thousands to the hospital every year. The good news? You can prevent it. The key is knowing exactly what to do when youâre too sick to eat, too nauseous to drink, or too tired to think clearly.
Never Skip Your Insulin, Even If Youâre Not Eating
This is the most critical rule, and itâs the one most people get wrong. You might think, âI didnât eat breakfast, so I donât need my insulin.â Thatâs a dangerous mistake. When youâre sick, your liver dumps extra glucose into your bloodstream to help your body fight infection. At the same time, stress hormones like cortisol and adrenaline make your body resistant to insulin. The result? Blood sugar can jump 30-50% higher than normal-even if youâre not eating a thing.Long-acting insulin (like Lantus, Levemir, or Basaglar) is your anchor. You need it to keep your body from breaking down fat and producing ketones. Skipping it, even for one dose, can trigger DKA within hours. Studies show that up to 30% of DKA cases happen because people reduced or stopped their insulin when they were sick. Donât do it. Keep your basal insulin on schedule. If you use an insulin pump, you may need to increase your basal rate by 20% for 12 hours if ketones are moderate or high. If you use injections, keep your usual dose. Talk to your doctor before making bigger changes.
Check Your Blood Sugar Every 2-4 Hours
Normal monitoring isnât enough when youâre sick. You need to check more often-not just in the morning and at night. For adults, check every 3-4 hours. For children, check every 2-3 hours. Thatâs not optional. Itâs your early warning system.Use these numbers as your guide:
- Below 100 mg/dL (5.6 mmol/L): Risk of low blood sugar. Time to take fast-acting carbs.
- 100-180 mg/dL (5.6-10 mmol/L): Target range during illness. Stay hydrated and keep insulin going.
- 180-240 mg/dL (10-13.3 mmol/L): High. Give a correction dose of rapid-acting insulin.
- Over 240 mg/dL (13.3 mmol/L): Danger zone. Test for ketones immediately.
If your blood sugar stays above 240 mg/dL for two checks in a row, donât wait. Test for ketones right away. Donât assume youâre fine because youâre not vomiting or feeling dizzy. DKA doesnât always come with obvious symptoms until itâs too late.
Ketone Checks Are Non-Negotiable
Ketones are your bodyâs emergency fuel. When it canât use glucose for energy, it burns fat instead. Thatâs normal during fasting-but not during illness. When youâre sick and insulin is low, your body overproduces ketones. Too many, and your blood becomes acidic. Thatâs DKA.Use a blood ketone meter, not urine strips. Urine tests are slow, unreliable, and can show ânegativeâ even when youâre in danger. Blood ketone meters give real-time numbers:
- Below 0.6 mmol/L: Normal
- 0.6-1.5 mmol/L: Moderate. Increase insulin, drink fluids, retest in 2 hours.
- Over 1.5 mmol/L: High. Call your doctor or go to the ER. If you use a pump, change your infusion site immediately.
One Reddit user, u/SickDayStruggles, shared how conflicting advice from two doctors led to a DKA hospitalization. One said to skip insulin when vomiting. The other said never to stop it. He followed the first-and ended up with ketones at 22 mmol/L. He survived, but barely. Donât be that person. Trust the science: ketones above 1.5 mmol/L mean you need help now.
Hydration Is Your Lifeline
When your blood sugar is high, your kidneys work overtime to flush out excess glucose. That pulls water out of your body. Dehydration makes everything worse-it thickens your blood, makes insulin less effective, and speeds up ketone buildup.Drink fluids constantly. Adults should aim for 6-8 ounces every hour. For kids, use the âage in ouncesâ rule: a 10-year-old needs 10 ounces per hour. Donât wait until youâre thirsty. Sip even if you feel nauseous.
What you drink matters too:
- If blood sugar is under 100 mg/dL: Use sugary drinks like regular soda, juice, or Gatorade (15g carbs per 8 oz).
- If blood sugar is between 100-180 mg/dL: Mix half sugary fluid with half water. This keeps you hydrated without spiking sugar.
- If blood sugar is over 180 mg/dL: Stick to sugar-free fluids like water, unsweetened tea, or diet soda.
Some people try to âpower throughâ vomiting by forcing fluids. Donât. If you canât keep anything down for more than 4 hours, call your doctor or go to the ER. IV fluids are often the only way to break the cycle.
Carbohydrates Still Matter-Even When Youâre Sick
You donât need to eat a full meal. But you do need to keep your body from burning fat. That means getting in 15-50 grams of carbohydrates every few hours, even if youâre not hungry.For adults: Aim for 50 grams of carbs every 3-4 hours. For kids: 15 grams per serving, every 1-2 hours. Choose easy-to-digest sources:
- Glucose tablets or gel
- Applesauce or banana
- Plain crackers or toast
- Regular gelatin or popsicles (check labels for sugar content)
If youâre on insulin, youâll need to cover these carbs with your usual insulin-to-carb ratio. Donât skip correction doses just because youâre sick. Your body still needs insulin to process glucose-even if itâs coming from a juice box.
Type 1 vs. Type 2: The Differences Matter
Not all diabetes is the same when youâre sick. Type 1 patients are at much higher risk for DKA because they have no insulin production. For them, ketone checks are mandatory during any illness.Type 2 patients on insulin also need to check ketones if blood sugar is over 240 mg/dL. But if youâre on pills like metformin or GLP-1 agonists, ketone testing isnât always needed-unless your blood sugar stays high for more than a day. Still, you should monitor closely. Illness can make Type 2 patients suddenly need insulin, even if theyâve never used it before.
Also, your target blood sugar range widens during illness. For Type 2, aim for 110-180 mg/dL. For Type 1, 100-180 mg/dL is safer. Donât stress over perfection. Focus on avoiding lows and preventing ketones.
Build Your Sick Day Kit Now
Donât wait until youâre feverish to scramble for supplies. Put together a sick day kit now:- Extra ketone test strips (check expiration dates-expired strips can give false negatives)
- Glucose tablets or gel
- Electrolyte drinks (sugar-free and sugary options)
- Easy-to-digest snacks (crackers, applesauce, broth)
- Extra insulin and syringes or pump supplies
- A measuring cup (8 oz) to track fluid intake
- A list of emergency contacts and your doctorâs number
Store it in a cool, dry place. Check it every 3 months. Replace expired strips. Keep your glucagon kit handy too-especially if youâre prone to lows.
When to Call for Help
You donât have to tough this out alone. Call your doctor or go to the ER if:- Your ketones are over 1.5 mmol/L and rising
- Youâve been vomiting for more than 4 hours
- You canât keep any fluids down
- Your blood sugar stays above 300 mg/dL for two checks
- You feel confused, have trouble breathing, or your breath smells fruity
- Youâve lost 5 pounds or more in a few days
These arenât signs to âwait and see.â Theyâre red flags. DKA doesnât wait. Neither should you.
What About New Tech? CGMs and Closed-Loop Systems
If you use a continuous glucose monitor (CGM) or closed-loop system, youâre ahead of the game. But your device doesnât know youâre sick. It canât tell the difference between a spike from food and a spike from infection.Donât rely on alerts alone. Check your blood sugar with a meter if your CGM reads over 250 mg/dL for more than 12 hours. Even if your pump is automating insulin, you may still need to manually increase your basal rate. Most pump manufacturers now include sick-day protocols in their manuals-but you have to read them. And if your pump suspends insulin because of a low reading, you may need to override it during illness. Talk to your diabetes team about your deviceâs settings before you get sick.
Common Mistakes and How to Avoid Them
- Mistake: Skipping insulin because youâre not eating. Fix: Basal insulin is not optional.
- Mistake: Using urine ketone strips. Fix: Blood ketone meters are faster and more accurate.
- Mistake: Drinking only water when blood sugar is low. Fix: Use sugary fluids to prevent lows.
- Mistake: Taking OTC cold meds with sugar or alcohol. Fix: Read labels. Choose sugar-free and alcohol-free options.
- Mistake: Waiting until you feel awful to act. Fix: Start your sick day plan at the first sign of illness.
One of the biggest problems? Inconsistent advice. One doctor says ânever skip insulin.â Another says âcut it in half if youâre vomiting.â That confusion costs lives. Stick to evidence-based guidelines from the ADA, IDF, and CDC. If your doctor gives you conflicting advice, ask for the source. You deserve clear, consistent instructions.
Can I skip my insulin if Iâm vomiting and not eating?
No. Even if youâre not eating, your body still needs insulin to prevent ketone buildup. Skipping insulin during illness is the leading cause of diabetic ketoacidosis. Keep your long-acting insulin on schedule. If youâre vomiting, try small sips of fluids and take your insulin as usual. If you canât keep anything down for more than 4 hours, call your doctor or go to the ER.
Should I use urine or blood ketone tests?
Always use a blood ketone meter if you have one. Urine strips are outdated and unreliable. They can show a negative result even when ketones are dangerously high. Blood ketone meters give you real-time numbers and respond faster to changes. If you only have urine strips, use them-but treat any moderate or large result as a medical alert and act immediately.
How much fluid should I drink when Iâm sick?
Adults should drink 6-8 ounces of fluid every hour. For children, use the âage in ouncesâ rule: a 10-year-old should drink 10 ounces per hour. Choose fluids based on your blood sugar: sugar-free if over 180 mg/dL, half sugary/half water if between 100-180 mg/dL, and sugary fluids if under 100 mg/dL. Donât wait until youâre thirsty-sip constantly.
Do I need to eat carbs when Iâm sick?
Yes-even if youâre not hungry. Your body needs fuel to avoid breaking down fat and producing ketones. Aim for 15-50 grams of carbs every 3-4 hours. Choose easy-to-digest options like glucose tablets, applesauce, crackers, or juice. Cover these carbs with your usual insulin dose. Skipping carbs doesnât help your blood sugar-it makes ketones worse.
Is it safe to take over-the-counter cold medicine?
Some are, but many arenât. Check labels for hidden sugar, alcohol, or decongestants like pseudoephedrine, which can raise blood sugar. Choose sugar-free, alcohol-free options. Brands like Tussin DM Sugar-Free or Claritin-D (without sugar) are safer. Always test your blood sugar after taking any new medication-even if itâs labeled âfor diabetics.â
When should I go to the hospital?
Go to the ER if: your ketones are over 1.5 mmol/L and rising, youâve been vomiting for more than 4 hours, you canât keep fluids down, your blood sugar stays above 300 mg/dL for two checks, youâre confused or having trouble breathing, or youâve lost 5 pounds or more in a few days. These are signs of diabetic ketoacidosis, which requires emergency treatment with IV fluids and insulin.
Can I use my insulin pump normally when Iâm sick?
You can, but you may need to adjust it. Most pumps will not automatically increase your basal rate during illness. If ketones are moderate or high, youâll likely need to manually increase your basal rate by 20% for 12 hours. Also, change your infusion site if ketones are high-clogged sites can cause insulin delivery issues. Donât rely on automation alone during sickness.
If youâre managing diabetes, sick days are inevitable. But they donât have to be scary. With the right plan, the right tools, and the right mindset, you can get through illness without ending up in the hospital. Prepare now. Know your numbers. Trust your meter. And never, ever skip your insulin.
basal = non-negotiable.
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hydration + insulin + ketone checks = survival kit.
please share this with someone who needs it.
Doctors give conflicting advice because they're lazy. Pharmacies sell sugary cold meds because they make money. You think this is about health? It's about profit.
And you? You're just another statistic waiting to happen.
Stop trusting the system. Trust your meter. Trust your body. Or die quietly.
Why do they want you to drink sugar-free soda instead of real juice?
Something's off.
Also, why do they hate sugar so much? Sugar is natural!