What is High Blood Sugar + How Should I Treat It?

High blood sugar, which is medically referred to as hyperglycemia, happens when too much glucose (sugar) is trapped in your bloodstream due to a lack of insulin on board (IOB)—how much insulin is working in your body at one time. 

High blood sugar level: symptoms and ranges

Glucose is a source of energy for the body. Insulin helps move glucose into your cells so your body can use it. Without insulin, glucose stays in the blood instead of entering the cells, which can cause high blood sugar levels.

In nonpregnant adults, the target fasting blood glucose level with diabetes is 70-99 mg/dL (3.9–5.5 mmol/L). Most people without diabetes never have a blood glucose level above 140 mg/dL (7.8 mmol/L), even after eating a lot of carbohydrates—every person with diabetes’s dream!  .

In nonpregnant adults, diabetes is usually diagnosed when your fasting blood sugar is above 126 mg/dL (7.0 mmol/L) and/or your A1C is above 6.5%. A diabetes diagnosis is usually confirmed with repeat bloodwork from a lab. Although some people don’t have or recognize the classic warning signs of diabetes and are sometimes diagnosed when their blood sugar levels are dangerously high, leading to serious issues like diabetic ketoacidosis (DKA), hyperosmolar state (HHS), coma or even premature death. Experts say DKA and HHS can affect anyone at any age with any form of diabetes. Both DKA and HHS are different medical conditions but both involve high blood sugars. The main difference is that DKA involves the body producing ketones and HHS usually does not. 

Common signs and symptoms of high blood sugar include:

• Unquenchable thirst
• Dry mouth
• Fatigue
• Frequent urination
• Blurred vision
• Recurring infections
• Slow-healing cuts or sores
• Symptoms of diabetes ketoacidosis (DKA)
• Fruity-smelling breath
• Weight loss
• Abdominal pain
• Confusion
• Presence of ketones
• Vomiting
• Exhaustion
• Coma

When your blood sugar levels are consistently high, if you live with diabetes, that’s when diabetes complications can begin.

What’s the target blood sugar range?

Individual blood sugar ranges vary, so it’s important to speak with your healthcare team about your high blood sugar threshold. The device you use to monitor your glucose levels may measure your glucose levels differently and their target ranges vary. Many people with diabetes (PWD) using continuous glucose monitors (CGMs) aim to stay within the 70 to 180 mg/dL (3.9-10 mmol/L) range, more than 70% of the time but this target isn’t universally applied because each person manages diabetes slightly differently and the ranges vary based on age and health condition. 

Some may aim for time in tight range (TTIR), which asks PWD to stay within 70 to 140 mg/dL (3.9-7.0 mmol/L). Thanks to advancements in diabetes medications and technology, it is reasonable for more PWD with access to these tools and resources to aim for TTIR.

According to the American Diabetes Association, nonpregnant adults with diabetes using blood glucose meter (BGM), the target ranges are: 80-130 mg/dL (4.4-7.2 mmol/L)  before meals and <180 mg/dL (<10.0 mmol/L) 1-2 hours after the start of a meal.

Your blood sugar levels can go high or low without you feeling it. If you have been living with diabetes for a long time, you might not notice when your blood sugar gets too low (hypoglycemia) or high (hyperglycemia). These phenomena are sometimes referred to as hypoglycemia or hyperglycemia unawareness. 

This makes checking your blood sugar regularly especially important, either with a blood glucose meter (BGM) or a CGM. 

How do consistently high blood sugar levels impact your body?

High and low blood sugar levels can both be dangerous. Still, you might not realize the impact of high blood sugar on your body until later because it is not usually as immediately dangerous as low blood sugar. 

If you live with diabetes, you might not think about how frequently having 200 mg/dL (11.1 mmol/L) readings is affecting your body. But these highs aren’t “get out of diabetes complications” free cards.

If your blood sugar levels are chronically high, they can damage your:

• Eyes 
• Kidneys
• Nervous system
• Heart

In the short term, extremely high blood sugar levels can cause the following issues, whether you’re already living with diabetes or haven’t yet been diagnosed:

• Severe dehydration
• DKA (occurs mostly in people living with type 1 and some with type 2 diabetes)
• Hyperosmolar state (HHS)  (occurs mostly in people living with type 2 diabetes)
• Coma
• Premature death

Why does high blood sugar happen?

There are three basic ways blood sugar levels can rise in the body:

 When you eat carbohydrates, your blood sugar levels go up. Some carbohydrates raise blood sugar levels faster and have a bigger impact than others. Eating protein may also increase your blood sugar levels. There are many factors to take into consideration when eating carbohydrates and protein that impact your blood sugar levels.  

1. The liver is always making sugar.
2. Illness, certain medications and hormones and stress can cause insulin resistance, which can raise blood sugar levels because insulin doesn’t work as well. 

In a person without diabetes, the body produces insulin to help the person process food and prevent the liver from producing too much sugar. If someone without diabetes gets stressed and their body becomes resistant to insulin, the pancreas just releases more insulin to manage it. 

How do high blood sugars affect people with T1D?

When you have insulin-requiring diabetes (some people with type 2 and all people with type 1), it’s important to give the right amount of insulin to match what you eat, the glucose your liver makes, and other situations like stress, illness or menstrual cycles for women.

Sometimes you might give too much or too little insulin, which can cause your blood sugar to be too low or too high. It will happen the longer you live with diabetes—you’re human! Balancing this can be hard, but new technologies can help you stay on track.

How to manage high blood sugars on sick days

Make a plan with your healthcare team for sick days because your insulin needs might change. If you use an insulin pump, you might even have a special “sick day” setting you can turn on. Ask your insulin pump rep if you’re unsure or reach out to your healthcare team.

Watch your blood sugar closely and check for ketones when you’re not feeling well to avoid high blood sugar. Talk to your healthcare team about how you’re feeling and ask questions about changing your insulin dosing strategy.

Random ways your blood sugar can spike

Sometimes, high blood sugar can happen if your insulin gets old or is exposed to severely hot or cold temperatures. Keep your insulin at the right temperature to make sure it works. Throw away any insulin that has expired. 

Also, write down the date when you open a vial or pen, because once opened, insulin usually lasts about 30 to 56 days. If it’s been longer than that since you opened it, even if some insulin is left, you should probably get rid of it. Read the label on your box to be sure how long it lasts.

Your environment isn’t the only random thing that can cause blood sugar spikes! Weirdly, sometimes even low blood sugar levels can lead to highs.

Dr. Osama Hamdy from the Joslin Diabetes Center says that treating low blood sugar too quickly can cause it to rise again, a phenomenon called rebounding. If your blood sugar seems off for no reason, check your insulin pump and tubing (if you use one) to make sure they are not blocked, because blockages can prevent your body from getting the insulin it needs.

How to identify high blood sugar dangers at home

To stay on top of the dangers of high blood sugar at home, check your blood sugar level if you’re feeling sick. Then, measure ketones in your blood or urine, as most healthcare teams will advise.

Check for ketones if your blood sugar is over 250 mg/dL (13.9 mmol/L)  or as your healthcare provider recommends—some may suggest checking them even sooner at 200mg/dL (11.1mg/dL).

You might also need to test for ketones if your blood sugar is unexpectedly high and doesn’t go down with a correction dose of insulin, especially if you’re using an insulin pump. Tell your diabetes team if your ketones are positive or higher than the target level.

Depending on the results, you may require immediate medical attention.

How to treat high blood sugar

If you’re sick, follow the sick day rules you’ve set with your healthcare team. If you haven’t made any, call them to talk about what to do. If you don’t have a healthcare team and are sick, you may need to seek immediate medical care. If you do not need immediate medical care, ask your community for help or use resources like this to create a plan that works for you. 

If you’re unsure where to start with your high blood sugar management plan, here are a handful of quick tips:

• Don’t exercise if you have ketones: If your blood sugar is high and you don’t know why, especially if you’re sick or have ketones, don’t exercise. But if your blood sugar is high from carbs and you don’t have ketones, you can exercise to help lower it.
• Stay hydrated: Drink plenty of water or a sugar-free electrolyte drink (like Gatorade Zero or Powerade Zero) to prevent dehydration and help your body get rid of sugar in your urine.
• Check your diabetes tech, if you have it: Evaluate your pump, tubing and infusion set to ensure there are no kinks or other issues that block insulin delivery.
• Double-check your insulin is safe for use: Make sure your insulin isn’t expired and hasn’t been exposed to extreme temperatures (hot or cold) or otherwise gone bad. You might need a new, unopened vial of insulin if you notice any signs of spoilage, like discoloration, cloudiness or a foul smell.
• Seek medical attention: If you are throwing up and cannot keep fluids down, you may need to go to the emergency room. When in doubt, seek emergency care.
• Communicate with your doctor: Staying in touch with your healthcare team while you’re navigating a random streak in high blood sugar levels or high blood sugar levels associated with illness can help prevent escalations, such as the need for a hospital stay.
• Know when to seek support: In addition to having a sick day plan, talk with your doctor about when you should get medical help. Ask questions about the best way to treat high blood sugar for you, what to do if you can’t keep down food or liquids and how to prevent high blood sugar episodes.

High blood sugar sucks and you can handle it

High blood sugar levels can be scary and sometimes feel unavoidable. In life with diabetes, whatever type you have, you will inevitably experience highs. This guide can help you feel empowered to get proactive about them and manage them well without rage bolusing (giving yourself too much insulin to correct a high) or rebounding.

Diabetes is tough, but you are tougher! Even on your worst days, you can pick yourself back up and move forward. With the tips in this guide and the support of your healthcare team and community, you are sure to regain the stability you seek in your blood sugar management.

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