Sick Day Rules for Diabetes Medications: Preventing DKA and AKI

When You’re Sick, Your Diabetes Medications Can Turn Dangerous

Feeling under the weather is bad enough. But if you have diabetes, a simple cold or stomach bug can quickly become life-threatening-not because of the illness itself, but because of what you’re doing to manage it. Many people keep taking their diabetes meds exactly as usual when they’re sick, not realizing that some of those medications can cause serious harm when you’re dehydrated, vomiting, or running a fever. The result? Diabetic ketoacidosis (DKA) or acute kidney injury (AKI), two emergencies that land thousands in the hospital every year.

According to CDC data from 2023, about 12.7% of all diabetes-related hospitalizations happen because someone kept taking the wrong medication-or didn’t stop one they should have-while sick. That’s over 150,000 preventable hospital stays in the U.S. alone. And it’s not just older adults. People of all ages, even those who’ve had diabetes for years, get caught off guard. The truth? Most of us were never taught how to adjust our meds when we’re ill. We were told to take them daily, so we do-no matter what.

Which Medications Must Stop When You’re Sick?

Not all diabetes drugs behave the same when you’re unwell. Some are safe to keep taking. Others need to be paused immediately. Here’s what you need to know, broken down by medication class.

• Metformin: Stop it the moment you start vomiting, have diarrhea, or develop a fever above 100.4°F (38°C). Metformin is cleared by your kidneys. When you’re sick and dehydrated, your kidney function drops. That causes metformin to build up in your blood, increasing your risk of lactic acidosis-a rare but deadly condition. A 2019 NEJM study found this risk jumps 8.3 times during illness. Even if you feel fine, if you’re not drinking enough fluids, don’t take metformin.
• SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin): These must be stopped at the first sign of illness. They work by making your kidneys flush out sugar through urine. When you’re sick, your body starts breaking down fat for energy, which produces ketones. SGLT2 inhibitors make this process worse, leading to euglycemic DKA-a dangerous form of ketoacidosis where your blood sugar isn’t sky-high, but your ketones are. The FDA reported a 7.2-fold increase in DKA cases linked to these drugs during illness. Don’t wait for symptoms. Stop them now.
• ACE inhibitors and ARBs (lisinopril, losartan, ramipril, valsartan): These are often prescribed for blood pressure or kidney protection. But when you’re dehydrated, they can crash your kidney function. If you’re drinking less than 1,500 mL (about 6 cups) of fluid in 24 hours, pause these meds. A 2022 meta-analysis showed a 40% higher risk of AKI in diabetes patients on these drugs during illness. Your kidneys need fluid to work. No fluid? No ACE/ARBs.

Insulin is different. You almost always need to keep taking it-even more than usual. Type 1 diabetes patients should increase their basal insulin by 10-20% every 4 hours if blood glucose stays above 15 mmol/L (270 mg/dL). Type 2 patients on insulin may also need higher doses, especially if blood sugar is rising. A 2023 Diabetes Care trial showed 68% of type 2 patients needed more insulin during illness. Skipping insulin when sick is one of the fastest ways to trigger DKA.

How Often Should You Check Blood Sugar and Ketones?

When you’re well, checking blood sugar twice a day might be enough. When you’re sick, that’s not nearly enough.

Test your blood glucose every 2 to 4 hours-minimum six times a day. Set alarms on your phone. Write each reading down. Don’t guess. Don’t assume you’ll remember. If your blood sugar is over 240 mg/dL (13.3 mmol/L), test for ketones. Use urine strips or a blood ketone meter. Urine ketones above 1.5 mmol/L or blood ketones above 0.6 mmol/L mean you’re in danger. Call your doctor or go to the ER. Don’t wait. Don’t try to “power through.”

Many people think DKA only happens when blood sugar is above 400 mg/dL. That’s false. Euglycemic DKA-caused by SGLT2 inhibitors or prolonged fasting-can happen with blood sugar as low as 150 mg/dL. That’s why ketone testing is non-negotiable.

Hydration Is Your Lifeline

Dehydration is the silent trigger for both DKA and AKI. When you’re vomiting, having diarrhea, or just not feeling like eating or drinking, your body loses fluids fast. And your kidneys can’t filter waste without enough water.

Drink at least 1,500 mL (6 cups) of fluid every 24 hours. If you’re vomiting or have a fever, aim for more. Water is fine, but electrolyte drinks help too. Avoid sugary sodas unless you’re treating low blood sugar. Sugar-free options like Nuun Hydration, Zero, or even broth work well. Sipping small amounts often is better than chugging. If you can’t keep fluids down for more than 4 hours, get help. That’s an emergency.

What About Hypoglycemia? Don’t Ignore It

Sick days aren’t just about high blood sugar. If you’re eating less or vomiting, your blood sugar can crash-especially if you’re on sulfonylureas (like glipizide) or insulin. Hypoglycemia during illness is dangerous because your body can’t respond normally. You might not feel the warning signs like shaking or sweating.

Use the 15-15 rule: If your blood sugar drops below 70 mg/dL, take 15 grams of fast-acting carbs-4 glucose tablets, ½ cup of juice, or 1 tablespoon of honey. Wait 15 minutes. Test again. Repeat if needed. Don’t wait to eat a full meal. Your body needs quick fuel to fight infection.

Prepare a Sick-Day Kit Before You Get Sick

Waiting until you’re vomiting to figure out what to do is too late. Build a sick-day kit now. Keep it in a visible spot-next to your meds or by your bed.

• Glucose meter with 50+ test strips
• Ketone strips (urine or blood) - at least 10
• 7-day supply of all your medications (in case you can’t get to the pharmacy)
• 6 bottles of sugar-free drinks (water, electrolyte solutions, tea)
• Electrolyte packets (Nuun, Liquid IV, or similar)
• Fast-acting carbs (glucose tablets, juice boxes, honey packets)
• ADA Sick Day Log (print it out or save it on your phone)

One study found that 78% of patients who used a prepared sick-day kit avoided hospitalization during illness. That’s not luck. That’s preparation.

Conflicting Advice? You’re Not Alone

Here’s the frustrating part: You might get different advice from your endocrinologist, your GP, the ADA website, and your pharmacist. A 2024 survey of 1,200 patients found 28% were confused because guidelines contradicted each other. The ADA says you can keep metformin during mild illness. The IDF says stop it at the first sign of sickness. NICE (UK) says stop if you drink less than 1,200 mL/day. Joslin Center says “always take your meds unless told otherwise.”

That’s why you need to talk to your own care team-before you get sick. Write down their specific instructions. Keep them on your phone. Show them to ER staff if you go in. Don’t rely on internet searches when you’re feverish and scared.

When to Go to the Emergency Room

Don’t wait for the worst to happen. Go to the ER if you have:

• Blood sugar below 70 mg/dL that doesn’t improve after two rounds of 15-15 rule
• Ketones above 1.5 mmol/L for more than 2 hours
• Vomiting for more than 4 hours
• Diarrhea for more than 6 hours
• Signs of dehydration: dry mouth, no urine for 8+ hours, dizziness, sunken eyes
• Fruity-smelling breath, rapid breathing, confusion

These aren’t “wait and see” symptoms. They’re red flags. Emergency rooms are trained to handle DKA and AKI. They can give you IV fluids, insulin, and electrolytes faster than you can at home.

What’s Missing From the Guidelines

Current rules were made for the average adult with diabetes. But what about older adults with heart failure? Or people with kidney disease already? Or those on multiple meds? The guidelines don’t account for complexity. A 2023 study found 31% of elderly patients still had medication-related complications even when they followed the rules exactly.

Also, newer drugs like GLP-1 agonists (semaglutide, tirzepatide) don’t have clear sick-day advice yet. They’re not linked to DKA or AKI the way SGLT2 inhibitors are, but we don’t know how they interact with illness. That’s a gap. And it’s growing as more people start these weight-loss and diabetes drugs.

Your Action Plan: Do This Today

You don’t need to memorize every study or guideline. Just do these five things now:

1. Call your doctor or pharmacist and ask: “Which of my diabetes meds should I stop if I get sick?” Write down their answer.
2. Build your sick-day kit. Buy the items. Put them in one bag.
3. Set up phone alarms to check blood sugar every 3 hours starting tomorrow.
4. Download or print the ADA Sick Day Log. Keep it with your kit.
5. Teach one person in your household how to check your ketones and when to call 999.

These steps won’t make you invincible. But they’ll give you control when you need it most. Illness doesn’t wait. Neither should you.