Key Takeaways

• High blood sugar is usually defined as a glucose level of 180 mg/dL (10.0 mmol/L) or higher.

• Blood sugar levels of 240 mg/dL (13.3 mmol/L) or higher could indicate a life-threatening complication like diabetic ketoacidosis (DKA). If you have high blood sugar along with symptoms like nausea, abdominal pain, or confusion, go to A&E right away.

• Certain diabetes medications can also lower blood sugar as guided by your healthcare providers.

• Exercise can help to lower blood sugar. However, it’s important to use caution, because it can also make DKA worse. Very intense exercise may also raise blood sugar.

People with diabetes may sometimes experience hyperglycemia, or high blood sugar. In general, this is defined as a glucose level of 180 mg/dL (10.0 mmol/L) or greater. However, some people with diabetes may have different blood sugar targets, so your personal definition of hyperglycemia may be slightly different – your medical team will discuss this with you. When blood sugar is 240 mg/dL (13.3 mmol/L) or greater, this is considered to be very high blood sugar. This is potentially in the range where it could indicate a serious health complication. 

Over the long term, high sugar levels cause damage to many systems throughout the body. This is what leads to the long-term complications of diabetes, such as vision loss, kidney disease, and nerve damage. This is one reason why it’s important to address high blood sugar levels. The less time your blood sugar spends in the range of 180 or greater, the lower your risk of long-term complications.

In the short term, very high blood sugar can also be dangerous. It can be associated with diabetic ketoacidosis (DKA) or diabetic hyperosmolar syndrome, which are very serious conditions that can even be fatal if left untreated. 

If you’re experiencing high blood sugar levels along with symptoms like nausea and vomiting, abdominal pain, severe thirst, dry mouth, weakness, or confusion, go to A&E right away. You may need immediate medical treatment to bring your blood sugar back down and prevent serious health complications or even death.

Can you lower blood sugar levels quickly?

The quickest and most reliable way to lower blood sugar is with insulin. If you have diabetes, and you normally take insulin to manage your condition, then you may be able to take some short-acting insulin to bring your blood sugar back under control. 

It’s important to calculate carefully to determine how much short-acting insulin you need, because using too much could cause an overcorrection and lead to a later episode of hypoglycemia (low blood sugar). Your medical team will help you learn how to determine the right amount of insulin to help bring down your blood sugar when it’s high. 

If you have been given insulin as part of your treatment, make sure to take short-acting insulin when you’re addressing an episode of hyperglycemia. Taking extra long-acting (basal) insulin will not help to bring your blood sugar down quickly and will also put you at risk for later hypoglycemia. After you’ve taken your extra insulin, check your glucose levels again in about 15 to 30 minutes, to see how your body has responded.

If your blood sugar is very high (at least 240 mg/dL or 13.3 mmol/L), it could result in a dangerous condition known as diabetic ketoacidosis (DKA). The symptoms of DKA include:

• Nausea and vomiting

• Abdominal pain

• Confusion

• A strange smell to the breath (often described as a “fruity smell”)

If you have these symptoms, it’s important to go to A&E immediately. DKA can be fatal if left untreated, so it’s important that you get treatment right away.

DKA is caused by a lack of insulin. Without insulin, the body’s cells are unable to take up sugar from the blood to use for energy. This is why the only treatment for DKA is insulin. Because DKA can be very dangerous, it’s best to head to A&E and allow medical professionals to take care of calculating the right insulin dose and administering it.

Very high blood sugar levels (greater than about 600 mg/dL or 33.3 mmol/L) can also lead to a condition called diabetic hyperosmolar syndrome. In this condition, large amounts of glucose enter the urine, and the glucose pulls large amounts of water with it. This can lead to severe dehydration. Symptoms of this condition include: 

• A dry mouth

• Severe thirst

• Confusion

• Weakness

If you have these symptoms along with high blood sugar, you should also seek medical attention immediately.

Diabetes Drugs such as metformin

Many people use diabetes medications other than insulin to manage their condition. They may wonder whether taking these medications will help to lower their blood sugar when it’s high.

In general, taking a diabetes medication like metformin won’t immediately lower your blood sugar level. These medications work on a longer-term basis, so if your blood sugar is high right now, then taking metformin won’t bring it down quickly. Although taking insulin can immediately lower blood sugar, the same isn’t true of all diabetes medications.

There are certain medications that can lower blood sugar quickly, including sulfonylureas (such as glipizide, glyburide, and glimepiride) and meglitinides (such as nateglinide and repaglinide). These medications work by stimulating insulin secretion from the pancreas. If you take one of these medications and you notice a high glucose level, check to see if you may have missed your medication dose. If so, taking the missed dose may help to bring your glucose level down. However, make sure that you don’t take two doses too close together, because this can lead to hypoglycemia.

With other diabetes medications, taking a missed dose of medication will not bring your blood sugar down quickly. However, regular use of diabetes medications can help to prevent instances of hyperglycemia. It’s important to be diligent and consistent about taking these medications as prescribed. This will help to prevent your blood sugar from rising too high.

Every time your blood sugar rises, this causes damage to your body. This is why it’s best to avoid blood sugar spikes, even if they’re corrected quickly. If you find that you’re experiencing frequent episodes of high blood sugar, it’s a good idea to work with your doctor to find ways to help prevent these from happening. Adjusting your diabetes medications may help to keep your blood sugar under better control. In some cases, adjustments to your lifestyle, such as your eating habits, might also help.

Other methods

There are also a few other ways to help address high blood sugar.

Exercise

Exercise tends to lower blood sugar. When you exercise, your muscles take up sugar from your blood and use it to fuel their activity. Insulin is normally needed to help glucose enter into cells. However, during exercise, the muscles are using glucose so rapidly that it’s able to enter into the muscle cell even without insulin. This is why exercise can lower blood sugar even without insulin.

However, if you normally take insulin and you’re running out of it, it’s not a good idea to use exercise as a substitute way to control your blood sugar. This is because a lack of insulin can lead to DKA, even though it lowers blood sugar. In fact, because exercise tends to generate ketones, it can make DKA worse. Ketones are a substance created when the body burns fats for energy, and in people with DKA, ketone levels are dangerously high.

In addition, intense exercise can cause your body to release epinephrine, also known as adrenaline. Epinephrine raises blood sugar by stimulating the liver to release glucose. Although moderate exercise may help to lower blood sugar, doing something very intense or competitive may actually have the opposite effect. 

Exercise also improves insulin sensitivity, and this effect may last for 24 hours or more after exercising. If you exercise regularly, this can help to keep your body in a more insulin sensitive state, which in turn will help to keep your blood sugar under control on a long-term basis.

Drinking Water

When your blood sugar is high, your kidneys have to filter out the excess sugar. This process requires a lot of water. Drinking extra water when you have a high glucose level can help to ensure that you don’t become dehydrated.

Drinking water can slightly dilute the sugar in your blood, which may make a small difference in your blood sugar level. By itself, this won’t be enough to correct a high blood sugar level. However, it’s still a good idea to drink plenty of water if you notice a high glucose level, to prevent dehydration.

Over the long term, studies have shown that people who drink more water have a lower risk for type 2 diabetes. It’s recommended that you take about eight glasses of water per day. If you don’t like plain water, you can take herbal tea or flavored water instead. However, make sure that you don’t choose a beverage that’s sweetened with sugar.

Support for keeping blood sugar from rising too high

It’s best to work on long-term blood sugar control, so that you avoid having episodes of high blood sugar. Although there are ways to lower your blood sugar when it spikes, it’s better to try to work on your blood sugar control so that you experience as few spikes as possible. Our NOVI Magnum clients have support from specialist physicians as well as nutritionists and health coaches. This helps them to develop and stick to a plan to keep their blood sugar under control, so they experience as few episodes of high blood sugar as possible.