If your blood sugar is high, the most effective immediate steps are drinking water, moving your body, and reducing your carbohydrate intake. How urgently you need to act depends on how high the number is. A reading above 250 mg/dL calls for closer monitoring and ketone testing, while anything above 600 mg/dL is a medical emergency.
What Counts as High Blood Sugar
A fasting blood sugar of 126 mg/dL or higher meets the diagnostic threshold for diabetes. After eating, blood sugar naturally rises, but a reading of 200 mg/dL or more two hours after a meal is considered elevated regardless of the circumstances. If you’re seeing numbers in these ranges for the first time, that’s worth a conversation with your doctor. If you already manage diabetes and your numbers are climbing unexpectedly, the steps below can help bring them down.
Three Things That Lower Blood Sugar Now
A combination of hydration, physical activity, and cutting back on sugars and carbs is the fastest way to bring your blood sugar down at home.
Drink water. Water helps your kidneys filter excess sugar out through urine. The more hydrated you are, the more urine your body produces, which flushes sugar from your bloodstream. Stick to plain water rather than juice, soda, or sports drinks, all of which add sugar back into the equation. Dehydration alone can spike blood sugar because the sugar in your blood becomes more concentrated when there’s less fluid.
Move your body. When you exercise, your muscles pull glucose out of the blood and burn it for energy. A walk, a bike ride, or even light housework can make a noticeable difference. That said, there’s an important exception: if your blood sugar is above 270 mg/dL, check your urine for ketones before exercising. When ketones are present, it means your body doesn’t have enough insulin to use glucose properly, and exercise can actually push blood sugar higher and trigger a dangerous condition called ketoacidosis. Wait until ketones clear before working out.
Skip the carbs for now. If your blood sugar is already elevated, eating bread, rice, pasta, fruit juice, or sweets will only push it higher. Focus on protein, non-starchy vegetables, and healthy fats until your numbers come down.
If You Take Insulin
People who use rapid-acting insulin can take what’s called a correction dose to bring a high reading down. The general rule of thumb is that one unit of rapid-acting insulin lowers blood sugar by about 50 mg/dL, but this varies widely from person to person. Some people see a drop of 15 mg/dL per unit, others closer to 100 mg/dL. Your doctor or diabetes educator should have given you a personal correction factor and a target blood sugar number. If you don’t have one, this is important to establish.
The math works like this: subtract your target blood sugar from your current reading, then divide by your correction factor. If your blood sugar is 220 mg/dL, your target is 120 mg/dL, and your correction factor is 50, that’s (220 – 120) ÷ 50 = 2 units. Never guess at a correction dose or stack extra insulin on top of a dose you recently took. Overlapping doses can cause a dangerous low blood sugar crash.
When to Check for Ketones
If your blood sugar is 250 mg/dL or above, or if you’re sick, check your blood sugar every four to six hours and test your urine for ketones. Ketone test strips are available at most pharmacies without a prescription.
Ketones build up when your body can’t get enough insulin to move sugar into cells, so it starts burning fat for fuel instead. In small amounts this isn’t dangerous, but high levels can lead to diabetic ketoacidosis (DKA), which is a medical emergency. Early warning signs include extreme thirst and urinating much more than usual. If it progresses, you may notice fast deep breathing, fruity-smelling breath, nausea, vomiting, stomach pain, dry skin, or severe fatigue. If you have ketones along with any of these symptoms, seek medical care immediately.
Surprising Triggers Worth Knowing
Food is the obvious culprit, but plenty of non-food factors push blood sugar up. Understanding them can help you figure out why your numbers are high in the first place.
- Poor sleep: Even one night of too little sleep makes your body use insulin less effectively the next day.
- Stress and pain: Stress hormones raise blood sugar directly. Even something like a sunburn can cause a spike because the pain triggers a stress response.
- Illness or infection: Your body releases hormones to fight infection, and those same hormones raise blood sugar. Gum disease, for example, is both a complication of diabetes and a contributor to higher readings.
- Time of day: Blood sugar tends to be harder to control later in the day. There’s also the “dawn phenomenon,” a natural early-morning hormone surge that can cause fasting blood sugar to be higher than expected.
- Dehydration: Less water in your body means sugar is more concentrated in your blood.
- Certain medications: Some nasal sprays contain chemicals that trigger your liver to release more glucose. Steroids are another common culprit.
If your blood sugar keeps climbing without an obvious dietary explanation, one of these hidden triggers is likely involved.
Blood Sugar Levels That Need Emergency Care
A blood sugar reading above 600 mg/dL is a medical emergency. At this level, you’re at risk for a condition called hyperosmolar hyperglycemic state, which can cause confusion, seizures, and loss of consciousness. Call your healthcare provider or go to an emergency room right away. Don’t try to manage a reading this high with home strategies alone.
Below 600 mg/dL but above 250 mg/dL, the priority is monitoring. Test for ketones, drink water, take your prescribed insulin if applicable, and recheck every few hours. If your blood sugar doesn’t start trending down within a couple of hours, or if you develop any symptoms of ketoacidosis, contact your provider.