Diabetes Sick Day Rules: What to Do When You're Ill and Blood Sugar Spikes

When you have diabetes, a condition where your body struggles to manage blood sugar, getting sick isn't just about feeling bad—it's a medical event. Your body releases stress hormones like cortisol and adrenaline when you're ill, which can send your blood sugar, the amount of glucose in your bloodstream soaring, even if you're not eating. That’s why diabetes sick day rules, a set of proven actions to follow when you’re unwell aren’t optional—they’re lifesaving. These rules help you avoid dangerous spikes, ketoacidosis, or dehydration when your body is under stress.

Many people think if they’re not eating, their blood sugar will drop. That’s a dangerous myth. Even if you can’t keep food down, your liver keeps dumping glucose into your blood. That’s why checking your blood sugar every 2 to 4 hours is non-negotiable. If you’re on insulin, you might need more, not less. Skipping doses because you’re nauseous can backfire badly. And don’t forget to check for ketones if your blood sugar stays above 240 mg/dL—this is how you catch diabetic ketoacidosis early. People with type 1 diabetes are at highest risk, but type 2 patients on insulin or certain pills need to watch closely too. Hydration matters just as much: sip water, broth, or sugar-free drinks. Avoid sugary sports drinks unless your blood sugar is crashing. If you’re vomiting, have diarrhea, or can’t keep fluids down for more than 4 hours, call your doctor. Don’t wait for it to get worse.

What you do on sick days often determines whether you end up in the ER or recover at home. It’s not about perfection—it’s about awareness. Know your personal thresholds: when should you call your provider? What’s your ketone alert level? Which meds should you pause or keep taking? Some diabetes pills, like SGLT2 inhibitors, need to be held during illness because they raise the risk of ketoacidosis. Others, like metformin, might need to be paused if you’re dehydrated. The diabetes sick day rules aren’t one-size-fits-all, but the core principles are: test often, stay hydrated, never stop insulin unless told to, and act fast when things go off track. Below, you’ll find real-world advice from posts that cover everything from insulin adjustments during infection to managing nausea with diabetes, and how to recognize when your body is in crisis. These aren’t guesses—they’re what people who’ve been there actually do to stay safe.