If your blood sugar is high, the most important first steps are hydrating with water, checking for ketones if you’re above 250 mg/dL, and taking a walk if your levels are below 270 mg/dL and ketones are absent. What you do next depends on how high your reading is and whether you use insulin. Here’s a practical breakdown.
Know When It’s an Emergency
Most blood sugar spikes can be managed at home, but certain thresholds require immediate medical attention. If your blood sugar stays at 300 mg/dL or above, go to the emergency room or call 911. The same applies if your breath smells fruity, you’re vomiting and can’t keep food or drinks down, or you’re having trouble breathing. These are signs of diabetic ketoacidosis (DKA), a serious complication that can escalate quickly.
If your blood sugar is 250 mg/dL or above, check your urine for ketones using an over-the-counter test strip. High ketones are an early warning sign of DKA. While waiting, drink water steadily and recheck your blood sugar every four to six hours. If ketones are present, don’t exercise, as physical activity can push levels higher when your body is already under metabolic stress.
Drink Water First
When blood sugar is elevated, your kidneys work harder to filter out excess glucose, pulling water from your tissues in the process. This makes dehydration both a symptom and an accelerator of high blood sugar. Drinking water helps your kidneys flush glucose through urine and can bring levels down faster than waiting alone. Aim for a glass every 30 minutes or so until your reading improves. Avoid juice, soda, or sweetened drinks, which will push glucose higher.
Move Your Body (With One Precaution)
Physical activity is one of the fastest ways to lower blood sugar without medication. When your muscles contract, they pull glucose out of the bloodstream for fuel, even without insulin. A 15- to 30-minute walk after a high reading can make a noticeable difference.
There’s one important exception. If your blood sugar is over 270 mg/dL, test your urine for ketones before exercising. If ketones are present, skip the workout entirely. When ketones are in your system, exercise can actually raise blood sugar further because your body doesn’t have enough insulin to use glucose properly. Wait until a ketone test shows clear results before you get moving.
Take a Correction Dose if You Use Insulin
If you’re on insulin, you likely have a correction factor your doctor has prescribed. This tells you how much one unit of rapid-acting insulin will lower your blood sugar. For example, if your correction factor is 50 and your blood sugar is 100 points above your target, you’d take 2 units. Your correction factor is personal to you, based on your total daily insulin dose and how sensitive your body is to it. If you don’t know yours, contact your care team rather than guessing.
After taking a correction dose, wait at least two hours before rechecking. Stacking doses (taking more insulin before the first dose has had time to work) is a common cause of dangerous low blood sugar later.
Adjust What You Eat Next
If your blood sugar is already high, your next meal matters more than usual. Focus on foods that won’t add another spike on top of the one you’re managing. Protein and fiber are your best tools here. Soluble fiber dissolves in your stomach and forms a gel-like substance that slows digestion, which helps prevent further glucose surges. Adults should aim for 22 to 34 grams of fiber per day, but in the short term, simply choosing fiber-rich foods at your next meal can help: vegetables, beans, nuts, or whole grains instead of refined carbs.
Pairing any carbohydrates with protein or healthy fat also slows glucose absorption. Eating an apple with peanut butter, for instance, produces a gentler blood sugar curve than eating the apple alone. If you’re not hungry, that’s fine. Skipping a meal won’t hurt in the short term, though skipping breakfast regularly can actually raise blood sugar after both lunch and dinner.
Figure Out What Caused the Spike
Once your levels come down, it’s worth thinking about what triggered the spike so you can prevent the next one. The obvious culprits are meals high in refined carbohydrates, missed medication, or incorrect insulin dosing. But several less obvious triggers catch people off guard.
- Poor sleep. Even a single night of inadequate sleep makes your body use insulin less effectively the next day.
- Stress and pain. Physical stress, including something as simple as a sunburn, triggers hormones that raise blood sugar.
- The dawn phenomenon. A natural surge of hormones in the early morning hours causes blood sugar to spike before you’ve eaten anything. This happens in everyone, but it’s more pronounced with diabetes.
- Decongestant nasal sprays. Some contain chemicals that signal your liver to release more glucose.
- Skipping breakfast. Going without a morning meal can lead to higher blood sugar after lunch and dinner, likely because your body overcompensates with stored glucose.
Tracking your readings alongside meals, sleep, stress levels, and medications for a few weeks can reveal patterns that are otherwise invisible. A continuous glucose monitor (CGM) makes this easier, and recent guidelines now support CGM use even for people with type 2 diabetes who aren’t on insulin.
Build Habits That Prevent Recurring Spikes
Managing an occasional spike is one thing. If your readings are frequently elevated, longer-term strategies become important. Resistance training (weightlifting, bodyweight exercises, resistance bands) improves your muscles’ ability to absorb glucose over time, not just during the workout. Current guidelines emphasize meeting resistance training benchmarks, typically two or more sessions per week, especially for people using weight management medications or who’ve had metabolic surgery.
On the nutrition side, eating patterns that prioritize plant-based proteins, fiber, and whole foods over processed carbohydrates produce the most consistent blood sugar control. The emphasis from major diabetes organizations in 2025 is on water as your primary beverage, limiting both sugary drinks and artificially sweetened ones. If you use artificial sweeteners, treat them as a short-term bridge toward reducing sweetness in your diet overall, not a permanent swap.
Some people ask about apple cider vinegar. A small study found that consuming about 2 tablespoons daily for eight weeks, alongside a healthy diet, lowered A1C from 9.2% to 7.8%. That’s a meaningful drop, but the study was small and participants also improved their diets. It’s not a substitute for medication or lifestyle changes, but it’s unlikely to cause harm in moderate amounts if you want to try it.