Sick Day Rules for Diabetes Medications: How to Prevent DKA and AKI During Illness

When you’re sick with a cold, flu, or stomach bug, your body is under stress. For people with diabetes, that stress can turn a minor illness into a medical emergency. Diabetic ketoacidosis (DKA) and acute kidney injury (AKI) don’t wait for you to feel better-they can strike fast, especially if you’re taking the wrong medications or skipping key checks. The good news? You can prevent most of these emergencies with simple, clear rules. The bad news? Many people don’t know them-or they’ve heard conflicting advice from different doctors.

Why Illness Is Dangerous for People with Diabetes

When you’re sick, your body releases stress hormones like cortisol and adrenaline. These hormones push your liver to dump more glucose into your bloodstream. At the same time, your body may not use insulin properly. For people with type 1 diabetes, this can trigger DKA-your body starts burning fat for energy because it lacks insulin, producing toxic ketones. For people with type 2, especially those on certain medications, dehydration from vomiting or fever can cause your kidneys to shut down, leading to AKI.

A 2022 study in JAMA Internal Medicine looked at nearly 48,000 hospital admissions and found that people with diabetes are 300% more likely to develop DKA and 200% more likely to suffer AKI when they’re sick. The biggest culprits? Not blood sugar levels alone-but what you’re taking to manage them.

Which Diabetes Medications to Stop (and When)

Not all diabetes meds are safe during illness. Some become dangerous when you’re dehydrated or not eating. Here’s what you need to know:

• Metformin: Stop immediately if you’re vomiting, have diarrhea, or have a fever. Metformin builds up in your blood when your kidneys aren’t working well, and that can cause lactic acidosis-a rare but deadly condition. A 2019 study in the New England Journal of Medicine showed the risk jumps 8.3 times when creatinine levels rise above 1.5 mg/dL. Even if you feel fine, if you’re not keeping fluids down, stop it.
• SGLT2 inhibitors (like empagliflozin, dapagliflozin, canagliflozin): These drugs must be stopped at the first sign of illness. They work by flushing sugar out through urine, which also pulls water with it. When you’re already dehydrated from vomiting or fever, this can trigger euglycemic DKA-dangerously high ketones even when your blood sugar looks normal. The FDA flagged this in 2021 after reviewing over 1,200 cases. Don’t wait for symptoms. Stop these meds the moment you feel unwell.
• ACE inhibitors and ARBs (like lisinopril, losartan, valsartan): These blood pressure meds protect your kidneys-but only when you’re hydrated. If you’re drinking less than 1,500 mL (about 6 cups) a day, pause them. A 2022 meta-analysis found that stopping these during dehydration cuts AKI risk by 40%. Many people don’t realize their blood pressure pill is also a kidney risk during illness.

Insulin is different. You almost always need to keep taking it-even more than usual. Type 1 patients should increase their basal insulin by 10-20% every 4 hours if blood sugar stays above 15 mmol/L (270 mg/dL). Type 2 patients on insulin often need higher doses too. One 2023 study found that 68% of type 2 patients needed more insulin during illness, not less.

What to Do Instead: Monitoring, Hydration, and When to Call for Help

Stopping meds is only half the battle. You also need to monitor, hydrate, and know when to get help.

• Check blood sugar every 2-4 hours. That’s at least 6 times a day. Don’t wait until you feel bad. Set phone alarms. Write down each reading. The target during illness is 100-180 mg/dL (5.6-10 mmol/L). Going higher than 240 mg/dL (13.3 mmol/L) means it’s time to test for ketones.
• Test for ketones if blood sugar is above 240 mg/dL. Use urine strips or a blood ketone meter. Blood ketones above 0.6 mmol/L or urine ketones above 1.5 mmol/L mean you’re at risk for DKA. Don’t ignore this. Call your doctor or go to the ER.
• Drink fluids constantly. Aim for at least 1,500 mL (6 cups) a day. Water, sugar-free electrolyte drinks, or broth are best. Avoid sugary sodas unless you’re treating low blood sugar. Dehydration is the silent trigger for both DKA and AKI.
• Don’t skip meals. Even if you’re nauseous, try to eat small amounts of carbs: toast, crackers, soup, or applesauce. Your body still needs fuel. If you can’t eat, sip on carbohydrate-containing drinks like regular soda or juice (15g carbs every hour if needed).
• Know the emergency signs: Vomiting for more than 4 hours, diarrhea for over 6 hours, ketones that don’t go down after 2 hours of fluids, or blood sugar below 70 mg/dL that doesn’t improve after 15g carbs. These are red flags. Don’t wait. Call 911 or go to the nearest emergency room.

Conflicting Advice? You’re Not Alone

One of the biggest problems? Doctors don’t all agree. The American Diabetes Association says you can keep metformin during mild illness if you’re hydrated. The International Diabetes Federation says stop it at the first sign of sickness. Your endocrinologist says one thing. Your GP says another. A 2024 survey found that 41% of patients got conflicting advice from different providers.

And then there’s the Joslin Diabetes Center’s advice: “Always take your diabetes medicine unless your provider tells you not to.” That’s dangerously vague. It ignores the fact that some meds can kill you if taken during illness.

Don’t rely on memory or guesswork. Write down your own sick day plan-based on your specific meds-and keep it with your glucose meter.

Build Your Sick Day Kit Now

Don’t wait until you’re sick to prepare. Do it now, before flu season hits.

Your kit should include:

• Glucose meter with 50+ test strips
• Ketone strips (urine or blood-have both if you can)
• 7-day supply of all your medications (including insulin)
• 6 bottles of sugar-free drinks (water, electrolyte solutions like Nuun)
• 10 packets of electrolyte replacement powder
• 15g carb snacks (glucose tablets, juice boxes, honey packets)
• Printed copy of your sick day plan (with doctor’s contact info)

Keep it in an easy-to-find spot. Many patients who survived serious illness say their kit saved them. One user on Reddit said, “I had the kit ready. When I got sick, I didn’t panic. I knew exactly what to do.”

What’s Missing From the Guidelines

The current rules work well for healthy, younger people with type 1 diabetes. In fact, following them reduces DKA risk by 73%. But they fall apart for older adults, people with kidney disease, heart failure, or multiple medications.

A 2023 study in the Journal of the American Geriatrics Society found that 31% of elderly patients still had complications-even when they followed all the rules. Why? Because guidelines treat everyone the same. A 300mg daily dose of metformin isn’t the same risk as 2,000mg. A person with stage 3 kidney disease needs different rules than someone with healthy kidneys.

Experts are calling for personalized sick day plans. One doctor put it bluntly: “We’re still using a one-size-fits-all checklist in a world of complex, aging patients.”

Until then, your best tool is knowledge-and a written plan.

Final Checklist: Your Sick Day Action Plan

Before you get sick, write this down and keep it with your kit:

1. Which meds do I stop? (Metformin? SGLT2 inhibitors? ACE/ARBs?)
2. Which meds do I keep? (Insulin? GLP-1 agonists? Sulfonylureas?)
3. What’s my target blood sugar range during illness?
4. When do I test for ketones? (Answer: Always when blood sugar >240 mg/dL)
5. How much fluid should I drink? (At least 1,500 mL/day)
6. What are my emergency signs? (Vomiting >4h, ketones >0.6 mmol/L, blood sugar <70 mg/dL not improving)
7. Who do I call? (Endocrinologist, primary care, ER)

Review this list every 6 months. Update it after every doctor visit. If you’re unsure about any medication, ask your provider to write it down. Don’t assume they’ll remember. You’re the one who has to live with the consequences.

Illness doesn’t care how well you manage your diabetes on good days. It only cares about what you do when you’re vulnerable. Get ready now. Your future self will thank you.

What to Do Next

If you haven’t made a sick day plan yet, do it today. Print out the ADA’s free Sick Day Log. Call your doctor and ask: “Which of my meds do I stop when I’m sick?” Get it in writing. Keep your kit stocked. Practice checking ketones now, so you’re not fumbling when you’re sick.

Diabetes doesn’t take a sick day. Neither should you. Being prepared isn’t just smart-it’s life-saving.