If your blood sugar is high, the three most effective things you can do right now are drink water, move your body, and take your prescribed medication if you have clear instructions to do so. How urgently you need to act depends on how high the number is and whether you’re showing signs of a more serious complication called diabetic ketoacidosis (DKA). Here’s how to bring your levels down and know when the situation requires emergency care.
Drink Water First
Water is the fastest, simplest tool you have. When you’re even mildly dehydrated, your overall blood volume drops while the amount of glucose stays the same, making your blood more concentrated and your readings higher. Drinking water dilutes that concentration and helps your kidneys flush excess glucose out through urine.
For a significant spike, aim for up to 30 ounces of water per hour for two to four hours, depending on how elevated your levels are. This approach works best for an unexpected or unusual spike rather than chronically elevated glucose. If plain water feels like a chore, unsweetened sparkling water or water with a squeeze of lemon counts. Avoid juice, regular soda, or sports drinks, which will push your glucose higher.
Move Your Body (With One Important Caveat)
Physical activity pulls glucose out of your bloodstream and into your muscles, where it’s burned for energy. Even a 15- to 20-minute walk after a meal can meaningfully blunt a post-meal spike. Parking farther from the entrance when you’re out, taking the stairs, or doing light housework all count as movement that helps.
There is a threshold where exercise becomes risky. If your blood sugar is above 270 mg/dL, you’re in a caution zone. Before working out at that level, test your urine for ketones using an over-the-counter test strip. If ketones are present, do not exercise. Physical activity when ketones are elevated can actually drive blood sugar higher and accelerate the progression toward DKA. Wait until a follow-up ketone test shows they’ve cleared before you resume any activity.
Take Medication Only as Directed
If you’re on insulin or another glucose-lowering medication, follow the correction instructions your doctor or nurse practitioner has given you. Insulin can be prescribed in specific amounts to lower a high reading, but taking extra without clear guidance risks a dangerous low blood sugar swing in the other direction. If you don’t already have a correction plan, a high reading is a good reason to contact your care team and ask for one. They can help you determine how much additional insulin (if any) to take based on your current number and your personal sensitivity to the medication.
Know When It’s an Emergency
Most high blood sugar episodes are uncomfortable but manageable at home. DKA is the exception, and it can become life-threatening quickly. The CDC recommends calling 911 or going to the emergency room if any of the following apply:
- Your blood sugar stays at 300 mg/dL or above despite your efforts to bring it down.
- Your breath smells fruity. This distinct odor comes from ketones building up in your blood.
- You’re vomiting and can’t keep food or drinks down. This prevents you from staying hydrated or taking oral medication.
- You’re having trouble breathing. Rapid, labored breathing is a hallmark sign of DKA.
If your blood sugar is 250 mg/dL or above, or if you’re sick with an infection or illness, check your blood sugar every four to six hours and test your urine for ketones each time. Moderate or high ketone levels warrant an immediate call to your care team or, if you can’t reach them, a trip to the ER.
Adjust What You Eat Next
Once you’ve addressed the immediate spike, what you eat over the next several hours matters. Fiber is your best ally because your body doesn’t break it down the way it breaks down other carbohydrates, so it doesn’t cause a secondary spike.
Soluble fiber, found in oats, black beans, apples, avocados, and Brussels sprouts, dissolves in water and forms a gel-like substance in your stomach that slows digestion. This gives your body more time to process glucose gradually instead of all at once. Insoluble fiber, found in whole wheat, bran, nuts, seeds, and fruit skins, helps improve your body’s sensitivity to insulin over time. Both types keep you feeling full longer, which makes it easier to avoid reaching for high-carb snacks that would start the cycle over again.
A practical next meal might look like grilled chicken over a large salad with avocado and seeds, or a bowl of lentil soup with a side of non-starchy vegetables. The goal is to pair protein and fat with fiber-rich carbohydrates so glucose enters your bloodstream slowly.
Track Patterns, Not Just Single Readings
A single high reading tells you something happened. A pattern of high readings tells you something needs to change. If you use a continuous glucose monitor (CGM), you can see your glucose plotted on a moving line throughout the day, which reveals trends that finger sticks miss. Many CGMs send alerts when your blood sugar is rising or falling quickly, giving you time to act before a number gets dangerously high.
The metric to watch is called time in range: the percentage of each day your glucose stays between 70 and 180 mg/dL. For most people with diabetes, the goal is to spend at least 70% of the day, roughly 17 hours, within that window. If you’re consistently falling short, sharing your CGM data with your care team can help them adjust your medication, meal timing, or activity recommendations based on real patterns rather than a single fasting number at an office visit.
Even without a CGM, keeping a simple log of your readings alongside what you ate, how you moved, and how you felt can surface the triggers behind your spikes. Many people discover that a specific meal, a stressful week at work, or poor sleep is the recurring culprit, and that knowledge makes prevention far easier than reaction.