If your blood sugar is high, the most effective immediate steps are drinking water, moving your body (with one important caveat), and taking your prescribed medication if you have it. For context, the American Diabetes Association recommends blood sugar stay between 80 and 130 mg/dL before meals and below 180 mg/dL one to two hours after eating. Anything consistently above those ranges needs attention.
Drink Water First
Dehydration makes high blood sugar worse through a simple mechanism: when there’s less water in your bloodstream, the glucose that’s already there becomes more concentrated. Your blood sugar reading climbs even if no new sugar entered your system. Drinking water helps dilute that concentration and supports your kidneys in flushing excess glucose out through urine.
This isn’t a cure, but rehydrating can meaningfully bring levels down, especially if you’ve been sweating, skipping fluids, or drinking sugary or caffeinated beverages. Plain water is ideal. Aim to drink steadily rather than forcing large amounts at once, and keep a glass nearby for the next several hours.
Move Your Body (If It’s Safe To)
Physical activity pulls glucose out of your bloodstream and into your muscles, where it gets used as fuel. Even a 15 to 20 minute walk after a meal can noticeably reduce a blood sugar spike. You don’t need intense exercise. Light to moderate movement like walking, cycling, or household chores works well.
There is one critical exception. If your blood sugar is above 270 mg/dL, exercise can actually make things worse. At that level, your body may be producing ketones, which are acidic byproducts that build up when your cells can’t access glucose properly. Exercising with high ketones raises the risk of a dangerous condition called ketoacidosis. If your reading is above 270, test your urine for ketones before doing anything active. Only exercise once a ketone test comes back negative. Until then, focus on hydration and medication instead.
Take Your Prescribed Medication
If you take insulin or another glucose-lowering medication, follow the plan your provider set up for high readings. Many people with diabetes have a correction dose of insulin, a specific extra amount calculated for situations exactly like this. That correction factor is personalized to you based on how sensitive your body is to insulin, so there’s no universal number. If you don’t already have correction instructions, this is worth discussing with your care team at your next visit.
If you don’t take insulin but use oral medication, make sure you haven’t missed a dose. A skipped pill is one of the most common reasons for an unexpected spike.
Choose Foods That Won’t Push It Higher
What you eat in the hours after a high reading matters. Foods with a low glycemic index cause a slower, smaller rise in blood sugar compared to refined carbohydrates. Some practical swaps that make a real difference:
- White rice to brown rice or converted rice
- Instant oatmeal to steel-cut oats
- White bread to whole-grain bread
- Baked potatoes to pasta or bulgur
- Cornflakes to bran flakes
- Corn to peas or leafy greens
In general, most fruits and vegetables, beans, nuts, and minimally processed grains fall into the low glycemic category (a score of 55 or below). These foods lead to steadier insulin release and avoid the sharp spikes that come from white bread, sugary snacks, or processed cereals. If you’re eating during a high blood sugar episode, lean toward protein, non-starchy vegetables, and healthy fats. Skip juice, soda, and anything with added sugar until your numbers come down.
Address Stress and Sleep
Stress is a surprisingly powerful driver of high blood sugar, even if you haven’t eaten anything problematic. When your body is under stress, it enters a survival mode: insulin levels drop, adrenaline and cortisol rise, and your liver dumps extra glucose into the bloodstream. At the same time, cortisol makes your muscle and fat tissue less responsive to insulin, so that extra glucose just stays circulating. The result is a blood sugar spike that seems to come from nowhere.
This applies to emotional stress, work pressure, illness, pain, and poor sleep. If you’re dealing with ongoing high readings and can’t pinpoint a dietary cause, consider whether stress or sleep deprivation is the hidden factor. Even basic stress reduction like slow breathing, a short walk outside, or getting to bed an hour earlier can improve your numbers over time. For people with diabetes, chronic stress often means needing higher medication doses to achieve the same control.
When High Blood Sugar Is an Emergency
Most high blood sugar episodes respond to water, movement, and medication within a few hours. But certain signs mean you need emergency care immediately. The CDC recommends calling 911 or going to the ER if:
- Your blood sugar stays at 300 mg/dL or above
- Your breath smells fruity
- You’re vomiting and can’t keep food or drinks down
- You’re having trouble breathing
These are signs of diabetic ketoacidosis, a condition where ketones build up to dangerous levels in your blood. It develops most often in people with type 1 diabetes but can happen with type 2 as well. Ketoacidosis can become life-threatening within hours, so don’t wait to see if symptoms improve on their own. If you have urine ketone strips at home and they show high ketones, that alone warrants urgent medical attention.
Building a Pattern That Keeps Levels Stable
Dealing with a single high reading is one thing. Preventing the next one requires looking at your daily habits as a whole. The three pillars are consistent: eating in a way that avoids large glucose spikes, staying physically active most days, and maintaining a healthy weight. None of these need to be extreme. Small, repeatable changes tend to work better than dramatic overhauls that don’t last.
Tracking your blood sugar before and after meals for even a week or two can reveal patterns you’d never notice otherwise. You might find that your morning oatmeal spikes you more than you expected, or that a 10 minute walk after dinner consistently drops your reading by 20 or 30 points. That kind of personal data is more useful than any general guideline, because your body’s response to food and activity is unique to you.