If your blood sugar is running high, the most effective immediate steps are drinking water, moving your body (with one important exception), and adjusting what you eat. What comes next depends on how high your numbers are and whether you’re dealing with a temporary spike or a persistent pattern. Here’s what to do in both situations.
Know Your Target Numbers
Before deciding how aggressively to act, it helps to know what “high” actually means. The American Diabetes Association’s 2025 guidelines set these targets for most nonpregnant adults with diabetes: fasting blood sugar between 80 and 130 mg/dL, and post-meal readings (taken one to two hours after eating) below 180 mg/dL. An A1C below 7% is the general long-term goal. If your numbers consistently land above these thresholds, something in your routine needs to change.
What to Do Right Now
Drink water. When blood sugar is elevated, your kidneys work harder to flush out the excess glucose, and dehydration makes the problem worse. Steady water intake throughout the day helps your body clear glucose more efficiently.
Go for a walk or do some light activity. A single bout of exercise pulls glucose out of your bloodstream and into your muscles, where it gets used for energy. Even a 15-minute walk after a meal can meaningfully blunt a glucose spike. Over time, regular exercise also improves your body’s ability to use insulin and increases the number of glucose transporter proteins in your muscles, making them better at soaking up sugar from the blood.
There is one critical exception: if your blood sugar is above 240 mg/dL, check your urine for ketones before exercising. If ketones are present, do not exercise. Physical activity when ketones are high can push your blood sugar even higher, not lower. This is especially important for people with type 1 diabetes, though it can apply to anyone.
When High Blood Sugar Is an Emergency
Most high readings are manageable at home, but certain signs mean you need emergency care immediately. The CDC advises calling 911 or going to the ER if:
- Your blood sugar stays at or above 300 mg/dL
- 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 (DKA), a dangerous condition where your body starts breaking down fat too rapidly and produces toxic levels of acids called ketones. If your blood sugar is 250 mg/dL or above, or you’re feeling sick, check your levels every four to six hours and test your urine for ketones. High ketones are an early warning sign of DKA, and catching it early matters.
Foods That Help Lower and Stabilize Blood Sugar
Carbohydrates have the most direct impact on blood sugar, so the type and amount you eat at each meal is the single biggest dietary lever you have. Not all carbs are equal. Foods are ranked on a glycemic index (GI) scale from 1 to 100, measuring how quickly they raise blood sugar. Low-GI foods (55 or below) cause a slow, gentle rise. High-GI foods (70 and above) cause a rapid spike.
Low-GI choices include green vegetables, most fruits, raw carrots, kidney beans, chickpeas, and lentils. Medium-GI foods include sweet corn, bananas, oats, and multigrain bread. High-GI foods that tend to spike blood sugar fastest include white rice, white bread, and potatoes. Swapping high-GI staples for low-GI alternatives at even one or two meals a day can reduce A1C by 0.2% to 0.5%, which is a meaningful shift.
Portion size matters just as much as food type. Researchers developed a measure called glycemic load (GL) to capture the real-world effect of eating a normal serving. A food might have a high GI but a low glycemic load if you typically eat small amounts of it. Paying attention to both the quality and quantity of carbohydrates is the most reliable way to control post-meal glucose spikes. If you take insulin at meals, learning to match your dose to your carbohydrate intake gives you far more flexibility and better control than following a rigid schedule.
Exercise as a Long-Term Tool
The guidelines recommend at least 150 minutes per week of moderate-to-vigorous activity, spread across three or more days, with no more than two consecutive rest days. That works out to roughly 30 minutes five days a week, though you can break it up however fits your life. Structured exercise programs lasting at least eight weeks lower A1C by an average of 0.66%, and higher intensity workouts produce greater improvements.
Resistance training (weights, bands, bodyweight exercises) two to three times per week on nonconsecutive days adds further benefit. Studies in older adults with type 2 diabetes show that combining aerobic exercise and resistance training works better than either one alone. One surprisingly effective habit: breaking up long periods of sitting every 30 minutes. Even standing up and moving briefly improves blood sugar compared to sitting continuously.
Weight Loss and Its Effect on Blood Sugar
Losing just 5% of your body weight, about 10 pounds for someone who weighs 200, is enough to measurably improve blood sugar control and reduce the need for glucose-lowering medications. For many people with type 2 diabetes, though, losing 7% or more produces the best results across blood sugar, cholesterol, and blood pressure. Working with a dietitian is one of the most effective ways to get there. Nutrition counseling has been shown to lower A1C by 0.5% to 2% in people with type 2 diabetes, a reduction comparable to some medications.
A practical calorie target for weight loss is roughly 1,200 to 1,500 calories per day for women and 1,500 to 1,800 for men, or simply cutting 500 to 750 calories from your current daily intake.
How Sleep and Stress Raise Blood Sugar
Poor sleep doesn’t just leave you tired. It directly raises blood sugar through several pathways. When you’re sleep-deprived, your body’s stress response system stays activated, signaling your liver to release more glucose into the bloodstream. Chronic poor sleep also disrupts cortisol patterns, keeping levels elevated well into the afternoon instead of dropping naturally after the morning. Sustained high cortisol promotes insulin resistance, meaning your cells stop responding normally to insulin and glucose builds up in the blood.
The same mechanisms kick in during psychological stress. Your body treats stress as a threat and dumps stored glucose into your bloodstream for quick energy, whether you need it or not. If you’ve noticed your blood sugar running higher during stressful periods or after several nights of poor sleep, you’re not imagining it. Prioritizing seven to eight hours of sleep and finding reliable ways to manage stress (physical activity, breathing exercises, whatever works for you) can make a real difference in your numbers.
How Medications Work
When lifestyle changes aren’t enough, medication is the next step. Metformin is typically the first medication prescribed for type 2 diabetes. It works by reducing the amount of glucose your liver releases and helping your body use insulin more effectively. Another class of medications works through the kidneys, blocking them from reabsorbing glucose back into the blood so that excess sugar leaves the body through urine.
If your current medication isn’t keeping your numbers in range, your doctor may adjust the dose, change the timing, or add a second medication. This isn’t a failure. Blood sugar management often requires fine-tuning over time as your body’s needs change.