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 your diabetes medications aren’t managed correctly. The good news? You can prevent both with clear, simple rules. The bad news? Many people don’t know them-or worse, they’ve gotten conflicting advice from different doctors.

Why Illness Changes Everything for Diabetes Medications

Your body doesn’t care if you’re sick or not-it still needs insulin to process sugar. When you’re ill, your liver dumps extra glucose into your bloodstream. At the same time, you might not be eating, drinking, or taking your meds like usual. That’s a perfect storm for high blood sugar and ketone buildup. For type 1 diabetes, this can lead to DKA. For type 2, especially if you’re on certain meds, it can trigger AKI.

A 2022 JAMA Internal Medicine study of nearly 48,000 hospital admissions found that people with diabetes are 300% more likely to develop DKA during illness. The risk of AKI jumps by 200%. And here’s the kicker: 12.7% of all diabetes-related hospitalizations happen because someone kept taking the wrong meds-or stopped the wrong ones-when they were sick.

Which Medications to Stop, Pause, or Keep

Not all diabetes meds act the same when you’re sick. Some are safe. Some are dangerous. And some can kill you if you keep taking them without fluids.

• Metformin: Stop immediately if you’re vomiting, have diarrhea, or have a fever. Why? Metformin can cause lactic acidosis when your kidneys are under stress. A 2019 NEJM study showed an 8.3-fold increase in risk when creatinine levels rise above 1.5 mg/dL. Even if you feel fine, if you can’t keep fluids down, stop it.
• SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin): These drugs increase glucose loss through urine. During illness, that can lead to euglycemic DKA-dangerously high ketones even when your blood sugar looks normal. The FDA issued a safety alert in 2021 after 1,247 adverse events linked to these drugs during illness. Discontinue at the first sign of fever, nausea, or vomiting. Don’t wait.
• ACE inhibitors and ARBs (lisinopril, losartan, valsartan): These blood pressure meds protect your kidneys when you’re healthy. But when you’re dehydrated? They can crash your kidney function. A 2022 meta-analysis found a 40% higher risk of AKI when fluid intake drops below 1,500 mL per day. Pause them if you’re not drinking enough.
• Insulin: This one’s different. You almost always need to keep taking insulin-even more than usual. Type 1 patients should increase basal insulin by 10-20% every 4 hours if blood sugar is above 15 mmol/L (270 mg/dL). Type 2 patients on insulin often need higher doses too. A 2023 Diabetes Care trial showed 68% of type 2 patients needed increased insulin during illness.
• Sulfonylureas (glimepiride, glyburide): These can cause low blood sugar when you’re not eating. If you’re not eating, talk to your provider about reducing the dose. Don’t stop cold turkey-just lower it.

How Often to Check Blood Sugar and Ketones

Checking your blood sugar once a day during illness? That’s not enough. You need to check every 2 to 4 hours-minimum six times a day. Set alarms on your phone. Write it down. Use the ADA’s Sick Day Log to track trends.

Target range during illness? 100-180 mg/dL (5.6-10 mmol/L). It’s okay if it’s a little higher. What’s not okay is letting it climb past 240 mg/dL (13.3 mmol/L) without checking ketones.

When your blood sugar hits that level, test for ketones. Use urine strips or a blood ketone meter. If your blood ketones are above 0.6 mmol/L or urine ketones above 1.5 mmol/L, call your doctor or go to the ER. Don’t wait. Don’t assume it’s just a bad day. DKA doesn’t wait.

Hydration Is Non-Negotiable

You can’t manage diabetes without fluids. When you’re sick, your body loses water through fever, vomiting, or breathing faster. Dehydration makes everything worse-higher blood sugar, higher ketones, higher risk of kidney injury.

Drink at least 1,500 mL (about 6-7 cups) of fluid every day. Water is best. Sugar-free drinks like diet soda, broth, or electrolyte solutions (Nuun, Pedialyte) work too. Avoid sugary drinks unless you’re treating low blood sugar.

If you can’t keep fluids down for more than 4 hours, call your provider. If you haven’t urinated in 8 hours, that’s a red flag for AKI. Swelling in your legs or ankles? That’s another sign your kidneys are struggling.

What to Do If You Can’t Eat

You don’t need to eat three meals a day when you’re sick. But you do need carbs-about 15 grams every hour if you can’t eat solid food. Why? Your body still needs fuel, and without carbs, it breaks down fat, which makes ketones.

Keep these on hand:

• Apple juice (4 oz = 15g carbs)
• Regular soda (not diet)
• Glucose tablets or gel
• Applesauce or yogurt

If your blood sugar drops below 70 mg/dL, take 15g of fast-acting carbs. Wait 15 minutes. Check again. Repeat if needed. This is the 15-15 rule-and it works even when you’re too sick to think clearly.

When to Go to the ER

You don’t need to panic over every high reading. But some signs mean it’s time to get help now:

• Blood sugar below 70 mg/dL and doesn’t improve after 30g of carbs
• Ketones above 1.5 mmol/L for more than 2 hours
• Vomiting for more than 4 hours
• Diarrhea for more than 6 hours
• Confusion, trouble breathing, fruity-smelling breath
• Not urinating for 8+ hours

If you’re unsure, call your doctor. If you can’t reach them, go to urgent care or the ER. It’s better to be safe than sorry. DKA and AKI don’t care if it’s 2 a.m. or a holiday.

Prepare a Sick Day Kit Before You Get Sick

Waiting until you’re vomiting to figure out what to do? That’s how people end up in the hospital.

Build a sick day kit by October 1-before flu season hits. Include:

• Glucose meter with 50+ test strips
• Ketone test strips (urine or blood)
• 7-day supply of all your diabetes meds (in original bottles)
• 6 bottles of sugar-free drinks (12 oz each)
• Electrolyte packets (Nuun, Pedialyte)
• 15g carb snacks (juice boxes, glucose gel, crackers)
• ADA Sick Day Log (print or save on phone)

Keep it in your fridge or pantry. Label it. Tell a family member where it is. If you live alone, give a copy of your sick day plan to a neighbor.

Why Everyone Gives You Different Advice

You’ve probably heard conflicting things. Your endocrinologist says stop metformin. Your primary care doctor says keep it. The ADA website says one thing. Your Reddit thread says another.

Here’s why: guidelines aren’t perfectly aligned. The ADA says you can keep metformin during mild illness. The IDF says stop it for any illness. NICE (UK) says pause meds if you drink less than 1,200 mL/day. The Joslin Center says, “Just take your meds unless your provider says otherwise”-which confuses 28% of patients.

And insulin? A 2023 audit found 43% of clinics give conflicting advice on how to adjust insulin during illness. That’s not your fault. It’s the system’s failure.

Here’s what to do: Write down your own plan with your provider before you get sick. Ask: “Which of my meds do I stop? When? What’s my ketone threshold? Who do I call at night?” Get it in writing. Save it on your phone. Stick it on your fridge.

What Experts Are Saying

Dr. Robert Gabbay (ADA): “The 5-day rule is non-negotiable. Restarting meds after 5 days without checking with your doctor causes 18% of preventable AKI cases.”

Dr. Anne Peters (USC): “Waiting 24 hours to stop an SGLT2 inhibitor after vomiting increases DKA risk by 300%.”

Dr. Irl Hirsch (UW Medicine): “Current guidelines treat everyone the same. Someone taking 300mg of metformin isn’t at the same risk as someone on 2000mg. We need personalized rules.”

The truth? The rules are solid for most people. But they’re not perfect. And they don’t account for older adults with heart or kidney disease-who make up the fastest-growing group of diabetes patients.

Real Stories, Real Consequences

One user on the ADA community wrote: “I stopped metformin during the stomach flu but didn’t know my lisinopril needed pausing too. I ended up in the hospital for three days with AKI.”

Another on Reddit said: “My endo said keep metformin. The ADA says stop. Who do I believe when I’m vomiting?”

These aren’t rare. A 2023 survey of 2,500 patients found 62% had a medication mismanagement incident during illness. Nearly 1 in 4 needed emergency care.

On the flip side, 78% of patients who used a prepared sick day kit avoided hospitalization. Preparation saves lives.

What’s Coming Next

By 2025, the ADA plans to update guidelines to include GLP-1 receptor agonists (like semaglutide and tirzepatide)-meds used by over 22 million Americans. Right now, there’s no clear sick day advice for them.

Apps like Glooko’s Illness Advisor (in beta testing) are starting to offer personalized alerts based on real-time glucose data. That’s the future: smart, adaptive, individualized.

But until then? Stick to the basics. Know your meds. Check your numbers. Drink water. Have a plan. And don’t trust advice from strangers online.

Frequently Asked Questions

Next Steps

If you have diabetes, do this today:

1. Look at your medication list. Identify which ones need to be stopped during illness.
2. Check your kit: do you have ketone strips? Enough glucose test strips? Sugar-free fluids?
3. Call your doctor and ask: “What’s my sick day plan?” Get it in writing.
4. Set phone alarms to check your blood sugar every 3 hours during illness.
5. Save the ADA’s 24/7 helpline number: 1-800-DIABETES.

Being sick is stressful enough. You shouldn’t have to guess whether your medicine will save you-or hurt you. Know your plan. Be ready. Your body will thank you.