If your blood sugar is high, the first step is to confirm the reading, then bring it down with hydration, movement, or a correction dose of insulin if that’s part of your plan. A normal pre-meal blood sugar is 80 to 130 mg/dL, and it should stay below 180 mg/dL two hours after eating. Anything consistently above those numbers counts as high.
Confirm the Reading First
Before you react, make sure the number is real. Glucose meters use a tiny drop of blood, which means even small contaminants on your fingertip can throw off the result. Sugar residue from fruit, candy, or juice is one of the most common culprits. Wash your hands with soap and water, dry them completely, and test again with a fresh strip.
Expired or improperly stored test strips can also give false highs. If strips have been left in extreme heat, cold, or stored loosely with the meter, the electrode inside can degrade. A second reading that’s significantly different from the first suggests a testing error rather than a true spike.
Drink Water
When blood sugar is elevated, your kidneys try to flush the excess glucose out through urine. This pulls water from your body and can leave you dehydrated quickly, which in turn concentrates the sugar in your bloodstream even further. Drinking water helps your kidneys do their job and supports the natural process of clearing glucose. Aim for steady sips rather than gulping a large amount at once. Avoid juice, soda, or anything sweetened, as those will push your levels higher.
Move Your Body (With One Important Exception)
Physical activity is one of the fastest ways to pull sugar out of your bloodstream because working muscles absorb glucose for energy. A 15 to 30 minute walk after a high reading can make a noticeable difference. You don’t need intense exercise. Even light movement like stretching or household chores helps.
There is one situation where exercise can backfire. If your blood sugar is above 250 mg/dL and you have type 1 diabetes, check for ketones first (using urine strips or a blood ketone meter). If ketones are elevated at 1.5 mmol/L or higher, skip the exercise entirely. When your body doesn’t have enough insulin, even mild activity can cause blood sugar and ketones to rise further, pushing you toward a dangerous condition called diabetic ketoacidosis. For people with type 2 diabetes who still produce insulin, this risk is much lower, but readings above 300 mg/dL are a signal to focus on hydration and medication rather than a workout.
Use Your Correction Dose if You Have One
If you take insulin and your care team has given you a correction factor, a high reading is exactly when to use it. A correction factor tells you how many points one unit of insulin will lower your blood sugar. For most people, that number falls somewhere between 20 and 100 mg/dL per unit. You subtract your target blood sugar from your current reading, divide by your correction factor, and that’s how many extra units to take.
For example, if your blood sugar is 280 mg/dL, your target is 120, and your correction factor is 40, you’d calculate (280 minus 120) divided by 40, which gives you 4 units. The correction dose typically takes 2 to 4 hours to bring you back into range. Don’t stack doses by taking more insulin before that window closes, as overlapping corrections are a common cause of low blood sugar later.
If you take oral medications rather than insulin, you generally can’t add an extra dose to fix a spike. Stick with hydration and movement, and note the pattern so you can discuss it with your provider.
Choose Foods That Won’t Make It Worse
If you’re hungry while your blood sugar is still elevated, reach for foods that won’t add to the problem. Protein and fiber are your best options. Protein has minimal impact on blood sugar, and soluble fiber (found in vegetables, beans, nuts, and oats) physically slows digestion by thickening the contents of your gut. This delays how quickly any glucose reaches your bloodstream.
Research on healthy adults found that adding soy protein and a type of soluble fiber called alginate to a sugary drink reduced the peak blood sugar response by as much as 58% compared to the drink alone. You don’t need specialty ingredients to get this effect. A handful of almonds, a hard-boiled egg, raw vegetables with hummus, or a small portion of cheese all work. The key is to avoid refined carbs, white bread, crackers, sweetened yogurt, or fruit juice until your levels come back down.
Consider What Caused the Spike
A single high reading isn’t always about food. Stress is a major and often overlooked trigger. When you’re under stress, your body releases adrenaline and cortisol, which signal the liver to dump stored glucose into your bloodstream. This happens whether you’ve eaten or not. Illness, infections, poor sleep, and pain can all produce the same hormonal response.
Other common causes worth checking:
- Missed or mistimed medication. Even taking insulin 15 minutes later than usual can shift the timing enough to cause a post-meal spike.
- Underestimated carbs. Restaurant meals, sauces, and “healthy” snack bars often contain more carbohydrates than expected.
- Dehydration. Starting the day without enough water can lead to a higher fasting reading by morning.
- Reduced activity. A day spent sitting affects insulin sensitivity noticeably compared to a day with even moderate movement.
Identifying patterns matters more than fixing any single spike. If you see highs at the same time of day or after the same types of meals repeatedly, that’s information your provider can use to adjust your plan.
Know the Emergency Warning Signs
Most high blood sugar episodes are manageable at home, but certain symptoms signal a medical emergency. Diabetic ketoacidosis can develop within 24 hours and requires immediate care. Watch for these red flags:
- Nausea or vomiting
- Belly pain
- Fruity-scented breath
- Shortness of breath
- Confusion or difficulty thinking clearly
- Extreme thirst combined with frequent urination
Seek emergency care if your blood sugar stays above 300 mg/dL on more than one test, especially if you have ketones in your urine and can’t reach your healthcare provider. This applies most urgently to people with type 1 diabetes, but anyone with persistent readings at that level and the symptoms above needs immediate attention.
Keeping Blood Sugar Stable Long Term
If high readings are becoming a pattern rather than an occasional event, the most useful number to track is your A1C, a blood test that reflects your average blood sugar over the past two to three months. The American Diabetes Association recommends an A1C below 7% for most adults with diabetes, though your individual target may be higher or lower depending on your age, health, and medication plan.
Day to day, the habits that prevent spikes are the same ones that bring them down: consistent meal timing, pairing carbohydrates with protein or fiber, staying hydrated, managing stress, and moving regularly. Small, repeated adjustments to these habits tend to produce more lasting results than dramatic changes that are hard to maintain.