Sick Day Rules for Diabetes Medications: What to Stop, Start, and When to Call for Help

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. The wrong move with your diabetes meds-like skipping a dose or keeping one you shouldn’t-can trigger diabetic ketoacidosis (DKA) or acute kidney injury (AKI). Both are life-threatening. And they happen more often than you think: nearly 1 in 8 diabetes-related hospital stays is caused by improper medication use during illness, according to CDC data from 2023.

Why Illness Changes Everything for Diabetes Meds

Your body doesn’t care if you’re sick or not-it reacts the same way. When you’re ill, your liver pumps out extra glucose. Your stress hormones rise. Your kidneys work harder. And if you’re not eating or drinking enough, your meds can turn dangerous.

Take metformin, for example. It’s safe when you’re healthy. But during vomiting, diarrhea, or fever, your kidneys can’t clear it properly. That builds up lactic acid in your blood-leading to lactic acidosis. Studies show this risk jumps 8.3 times when creatinine levels rise above 1.5 mg/dL. That’s why stopping metformin during illness isn’t optional-it’s essential.

Same goes for SGLT2 inhibitors like dapagliflozin or empagliflozin. These drugs make your kidneys flush out sugar through urine. Sounds good, right? But when you’re dehydrated from illness, they can trigger euglycemic DKA-even when your blood sugar looks normal. The FDA flagged this in 2021 after 1,247 adverse events. Waiting even 24 hours after vomiting to stop these meds increases DKA risk by 300%.

And don’t forget your blood pressure meds. ACE inhibitors and ARBs (like lisinopril or losartan) are common for people with diabetes. But when you’re not drinking enough fluids, they can cause your kidneys to shut down. A 2022 meta-analysis found a 40% spike in AKI when fluid intake drops below 1,500 mL a day. That’s just six 8-oz glasses. Easy to miss when you’re too sick to eat or drink.

What to Do When You’re Sick: The Medication Breakdown

There’s no one-size-fits-all rule. Your meds matter. Here’s what you need to know, based on the latest ADA and IDF guidelines (2023-2025):

• Metformin: Stop immediately if you’re vomiting, have diarrhea, or have a fever above 100.4°F (38°C). Don’t restart until you’ve eaten normally for 24 hours and your doctor says it’s safe.
• SGLT2 inhibitors (Jardiance, Farxiga, Invokana): Stop at the first sign of illness-even if you feel fine. No exceptions. Restart only after your provider clears you, usually after 2-5 days of being symptom-free.
• ACE inhibitors / ARBs: Pause if you’re drinking less than 1,500 mL (about 6 cups) of fluid in 24 hours. This includes water, broth, or sugar-free drinks. Don’t wait for symptoms like swelling or reduced urine output.
• Insulin: Never skip insulin, even if you’re not eating. Type 1 patients need 10-20% more basal insulin every 4 hours if blood sugar is above 15 mmol/L (270 mg/dL). Type 2 patients on insulin often need higher doses too-68% do, according to a 2023 Diabetes Care trial. Use your correction factor, but check with your provider if you’re unsure.
• Sulfonylureas (glipizide, glyburide): These can cause dangerous lows when you’re not eating. Talk to your doctor about reducing the dose or skipping it if you’re not eating solid food.
• GLP-1 agonists (Ozempic, Mounjaro): These are new, and guidelines are still catching up. Most experts recommend holding them during illness until you’re eating normally again. Check with your provider-don’t guess.

Monitoring: What You Must Track Every Day

When you’re sick, your usual routine goes out the window. But your monitoring can’t. Here’s what you need to check-and how often:

• Blood glucose: Test every 2-4 hours. That’s at least 6 times a day. Set alarms on your phone if you have to. Target range during illness: 100-180 mg/dL (5.6-10 mmol/L). Don’t panic if it’s a little high-focus on trends.
• Ketones: Test when your blood sugar hits 240 mg/dL (13.3 mmol/L) or higher. Use either urine strips or a blood ketone meter. If blood ketones are above 0.6 mmol/L or urine ketones are above 1.5 mmol/L, call your doctor or go to the ER. Don’t wait.
• Fluid intake: Aim for at least 1,500 mL (6 cups) of fluids daily. Water, sugar-free tea, broth, or electrolyte drinks like Nuun. Avoid sugary drinks unless you’re treating a low.
• Urine output: If you’re peeing less than usual-or not at all-that’s a red flag for AKI. So is swelling in your ankles or face.
• Body temperature: Fever above 100.4°F (38°C) means it’s time to stop metformin and SGLT2 inhibitors.

Emergency Signs: When to Call 999 or Go to A&E

These aren’t suggestions. These are alarms.

• Blood sugar below 70 mg/dL and doesn’t improve after 30g of fast-acting carbs (like juice or glucose tabs)
• Ketones above 1.5 mmol/L that don’t drop after 2 hours of fluids and insulin
• Vomiting for more than 4 hours
• Diarrhea for more than 6 hours
• Confusion, extreme fatigue, or fruity-smelling breath (signs of DKA)
• Little or no urine for 12+ hours, or swelling in legs/face (signs of AKI)

If any of these happen, don’t wait. Call 999 or go to your nearest emergency department. Say: “I have diabetes and I think I’m in DKA or AKI.” They’ll know what to do.

Prepare Ahead: The Sick-Day Kit

Waiting until you’re sick to figure this out is too late. Build your kit now-ideally by October, before flu season hits.

Here’s what to keep in your kit:

• Glucose meter with 50+ test strips
• Ketone strips (urine or blood-get both if you can)
• 7-day supply of all your diabetes meds (in original bottles)
• 6 sugar-free drinks (12 oz each)-water, tea, electrolyte drinks
• 10 packets of electrolyte replacement (Nuun, DripDrop, or similar)
• Fast-acting carbs: juice boxes, glucose tabs, honey packets
• ADA Sick Day Log (print it from ada.org)
• Written plan from your doctor: who to call, what meds to stop, emergency numbers

Keep this kit in one place-like your medicine cabinet or fridge. And make sure someone in your household knows where it is.

Conflicting Advice? You’re Not Alone

Here’s the messy part: not every doctor agrees. Some say keep metformin. Others say stop it. One endocrinologist told a Reddit user to “always take your meds unless told otherwise”-but that’s not what the ADA says.

A 2024 survey of 1,200 patients found 28% were confused by conflicting advice. And 41% got different instructions from their GP versus their diabetes specialist. That’s dangerous.

So here’s what to do:

• Ask your doctor for a written sick day plan before you get sick.
• Keep a copy on your phone and in your sick-day kit.
• If you’re unsure, call the ADA helpline: 1-800-DIABETES (available 24/7).
• Don’t rely on Google. Don’t trust random forum advice. Go to the source: ada.org or diabetes.org.uk.

Why This Matters More Than Ever

The number of people with diabetes in the U.S. is rising-34.2 million in 2023. And the flu season of 2024 saw a 27% jump in diabetes-related hospitalizations compared to 2022. Older adults, especially those with kidney disease or heart failure, are at highest risk. By 2030, nearly half of all diabetes patients will be over 65.

Current guidelines were made for healthy adults. They don’t fully account for frailty, multiple meds, or kidney decline. That’s why personalized plans matter. Your dose of metformin (300mg vs. 2,000mg) changes your risk. Your age, your other meds, your kidney function-these all change the rules.

That’s why the next big push in diabetes care is AI-driven tools. Apps like Glooko’s Illness Advisor (in beta as of late 2024) can suggest real-time dose changes based on your glucose trends. But until then, you’ve got to be your own advocate.

Bottom Line: Know Your Meds, Know the Signs, Act Fast

Being sick with diabetes doesn’t have to mean a hospital stay. But it does require preparation. You can’t wing it. You can’t hope for the best. You need a plan-and you need to follow it.

Stop metformin and SGLT2 inhibitors at the first sign of illness. Never skip insulin. Test your blood sugar and ketones often. Drink fluids. Know your emergency signs. And never hesitate to call for help.

It’s not about being perfect. It’s about being prepared. And that’s the difference between staying home-and ending up in the ER.