Treating hyperglycemia depends on how high your blood sugar is and whether you use insulin. For a mild spike, drinking water and taking a short walk can bring levels down within an hour or two. For blood sugar that stays above 250 mg/dL, you may need a correction dose of insulin, and you should check for ketones. If your reading exceeds 300 mg/dL and won’t come down, that’s a medical emergency.
Bring Down a Mild Spike
When your blood sugar is elevated but below 250 mg/dL, two things help most: hydration and movement. Drinking water helps your kidneys flush excess glucose through urine, and even a 15-minute walk prompts your muscles to pull sugar out of your bloodstream for energy. Check your blood sugar again 30 to 60 minutes later. If it’s trending down, you’re on the right track.
If you take rapid-acting insulin, a correction dose can speed things along. Most people and their doctors calculate a correction factor by dividing roughly 1,800 to 2,000 by their total daily insulin dose. The result tells you how many points one unit of insulin will lower your blood sugar. So if your correction factor is 50, and you’re 150 points above your target, you’d take about 3 units. Don’t stack correction doses, though. Wait at least two to three hours before dosing again, since rapid-acting insulin takes that long to finish working.
When to Check for Ketones
Once your blood sugar hits 250 mg/dL or higher, you should test for ketones. When your body can’t use glucose properly, it starts breaking down fat for fuel, producing ketones as a byproduct. Small amounts are manageable, but high levels make your blood dangerously acidic.
You can test with a urine strip or a blood ketone meter. Blood meters are more accurate and give a real-time number. A reading of 1.5 mmol/L or higher means ketones are elevated enough to be dangerous, and you should not exercise or wait it out at home. At that level, your blood sugar and ketones can climb even higher with mild physical activity.
Signs You Need Emergency Care
Diabetic ketoacidosis (DKA) is the most dangerous complication of untreated hyperglycemia. It develops over hours, sometimes faster during illness. Go to the emergency room or call 911 if:
- Your blood sugar stays at 300 mg/dL or above despite treatment
- Your breath smells fruity or sweet
- You’re vomiting and can’t keep fluids down
- You’re having trouble breathing
- You feel confused or unusually drowsy
In the ER, treatment centers on IV fluids to correct severe dehydration and insulin to bring glucose and ketones back to safe levels. The fluid deficit in DKA is significant. Doctors typically replace about half the lost fluid in the first 12 hours. Most people spend one to two days in the hospital during a DKA episode, though milder cases can resolve faster.
Exercise: When It Helps and When It Doesn’t
Exercise is one of the most effective tools for lowering blood sugar, but there’s a ceiling. The American Diabetes Association recommends checking for ketones before exercising if your blood sugar is 250 mg/dL or above. If ketones are present at moderate or large levels, skip the workout entirely. Exercise during active ketone production forces your liver to release even more glucose, making the problem worse.
Below that threshold, walking, cycling, or any moderate activity works well. Your muscles become more responsive to insulin during and after exercise, pulling glucose from your blood more efficiently. Even 10 to 15 minutes of movement after a meal can blunt a postprandial spike noticeably.
Food Swaps That Lower Blood Sugar Spikes
What you eat at your next meal matters. Swapping high-glycemic foods for lower-glycemic alternatives reduces the height and speed of your post-meal glucose rise. Some of the most impactful swaps are straightforward:
- White rice → brown rice or converted rice
- Instant oatmeal → steel-cut oats
- White bread → whole-grain bread
- Baked potato → pasta or bulgur
- Cornflakes → bran flakes
- Corn → peas or leafy greens
Pairing carbohydrates with protein, fat, or fiber also slows digestion and flattens the glucose curve. A piece of toast with peanut butter will spike your blood sugar less than the same toast eaten plain. If you’re dealing with persistent post-meal highs, tracking which specific foods cause the biggest spikes, using a glucose monitor, lets you make targeted changes rather than overhauling your entire diet.
Dealing With High Morning Blood Sugar
If your blood sugar is consistently high when you wake up, two different mechanisms could be responsible, and they require opposite treatments.
The dawn phenomenon is the more common cause. Your body releases a surge of hormones in the early morning hours (roughly 4 to 8 a.m.) that trigger your liver to dump glucose into your bloodstream. This happens to everyone, but in people with diabetes, there isn’t enough insulin response to counteract it. Oral medications alone often fail to control the dawn phenomenon. Insulin therapy, particularly through a pump that can increase delivery during those early morning hours, tends to work better. Lifestyle adjustments also help: exercising in the evening and eating a dinner higher in protein relative to carbohydrates have both been shown to improve morning readings.
The Somogyi effect is less common and somewhat debated among researchers. It occurs when blood sugar drops too low overnight, often from too much evening insulin or not enough food before bed, and the body overcorrects by releasing stored glucose. The result looks the same on your morning reading: high blood sugar. But the fix is the opposite. Instead of more insulin, you may need less, or a bedtime snack. To tell the two apart, check your blood sugar between 2 and 3 a.m. If it’s low at that hour, the Somogyi effect is likely. If it’s normal or already rising, the dawn phenomenon is your culprit. A continuous glucose monitor makes this distinction much easier since it tracks your levels all night without an alarm-clock finger stick.
Adjusting Medications for Ongoing Highs
If your blood sugar stays above target for weeks despite lifestyle efforts, your medication plan likely needs adjustment. The American Diabetes Association recommends reassessing your regimen every three to six months. Treatment changes shouldn’t be delayed when your numbers consistently miss the mark.
Metformin is typically the first medication prescribed for type 2 diabetes. If you’re starting it or increasing the dose, the most common side effects are bloating, stomach discomfort, and diarrhea. These usually improve if the dose is increased gradually rather than all at once, and extended-release versions cause fewer gut issues than standard tablets.
A newer class of medications, SGLT2 inhibitors, works by causing your kidneys to excrete more glucose in your urine. They also carry heart and kidney protective benefits independent of blood sugar lowering. One important safety note: these medications carry a small risk of DKA, even at near-normal blood sugar levels. If you’re sick, fasting for a procedure, or scheduled for surgery, your doctor will typically have you stop the medication three to four days beforehand.
When a new glucose-lowering medication is added to your regimen, any drugs that carry a higher risk of causing low blood sugar, like sulfonylureas or insulin, may need their doses reduced. The goal is to bring highs down without creating dangerous lows in the process.