Blood sugar spikes are caused when a simple sugar known as glucose builds up in your bloodstream. Most of the food you eat is broken down into glucose. Your body needs glucose because it’s the fuel that makes your muscles, organs, and brain work properly.
Glucose can’t be used as fuel until it enters your cells. Insulin, a hormone produced by your pancreas, unlocks cells so that glucose can enter them. Without insulin, glucose would keep floating around in your bloodstream with nowhere to go, becoming increasingly more concentrated over time.
When glucose builds up in your bloodstream, your blood glucose, or sugar, levels rise.
Blood sugar spikes occur in people with diabetes because they’re unable to use insulin effectively. Untreated high blood sugar can be dangerous, leading to a serious condition called ketoacidosis. Chronic high blood sugar increases the likelihood of serious diabetes complications like heart disease, blindness, neuropathy, and kidney failure.
Learning to recognize the symptoms of hyperglycemia, or high blood glucose, can help you keep your diabetes in control. Some people with diabetes immediately feel the symptoms of high blood glucose, but others go undiagnosed for years because their symptoms are so mild.
Symptoms of hyperglycemia typically begin when your blood glucose goes above 200 milligrams per deciliter (mg/dL). Symptoms get worse the longer you go untreated.
Symptoms of a blood sugar spike include:
- frequent urination
- increased thirst
- blurred vision
What to do
It’s important to know the symptoms of hyperglycemia. If you suspect that you have high blood sugar, perform a finger stick to check your number. Exercising and drinking water after eating, particularly if you consumed a lot of starchy carbs, can help lower your blood sugar. You can also use an insulin injection, but be careful to only use this method while closely following the recommendation of your doctor. If used improperly, insulin can cause hypoglycemia, or low blood sugar.
If high blood sugar levels go untreated for too long, glucose will build up in your bloodstream and your cells will be starved for fuel. Your cells will turn to fat for fuel. When your cells use fat instead of glucose, the process produces a toxic byproduct called ketones. This can lead to ketoacidosis, a condition that can result in diabetic coma or death.
Ketoacidosis is an emergency that requires immediate treatment. You should call 911 or seek emergency medical attention if you experience any of the following signs and symptoms:
- fruity smelling breath or sweat
- nausea and vomiting
- severe dry mouth
- trouble breathing
- pain in the abdominal area
Blood sugar levels fluctuate all day long. When you eat foods that are high in carbohydrates like bread, potatoes, or pasta, your blood sugar will immediately begin to rise. If your blood sugar is consistently high, you need to talk to your doctor about improving your diabetes management. Blood sugar rises when:
- you’re not taking enough insulin
- your insulin isn’t lasting as long as you think it is
- you’re not taking your oral diabetes medication
- your medication dosage needs adjusting
- you’re using expired insulin
- you’re not following your nutritional plan
- you have an illness or infection
- you’re using certain medications, like steroids
- you’re under physical stress, such an injury or surgery
- you’re under emotional stress, such as trouble at work or home or money problems
If your blood sugar is usually well controlled but you’re experiencing unexplained blood sugar spikes, then there might be a more acute cause. Try keeping a record of all the food and drinks you consume. Write down your pre-meal blood sugar reading, then test your blood sugar again an hour after eating and record that number. Even a few days of recorded information can help you and your doctor discover what’s causing your blood sugar spikes.
Common culprits include:
- Carbohydrates: Carbs are the most common problem. Carbs get broken down into glucose very quickly. If you take insulin, talk to your doctor and your insulin-to-carb ratio.
- Fruits: These are healthy, but they contain a type of sugar called fructose that raises blood sugar.
- Fatty foods: Fatty foods can cause what’s known as the “pizza effect.” Taking pizza as an example, carbohydrates in the dough and sauce will raise your blood sugar immediately, but the fat and protein won’t affect your sugars until hours later.
- Juice, soda, electrolyte drinks, and sugary coffee drinks: These all affect your sugars, so don’t forget to count the carbs in your drinks.
- Alcohol: Alcohol raises blood sugar immediately, especially when mixed with juice or soda. But it can also cause low blood sugars several hours later.
- Not exercising: If you don’t exercise as much as you usually do, your insulin isn’t working as effectively as it usually is. Talk to your doctor about adjusting your medication to fit your workout schedule.
- Over-treating low blood sugars: Over-treating is very common. Talk to your doctor about what to do when your blood glucose level drops.
- Work with a nutritionist to develop a meal plan. Planning your meals will help you avoid unexpected spikes. You might also want to look at The Ultimate Diabetes Meal Planner from the American Diabetes Association (ADA).
- Start a weight loss program. Losing weight will help your body use insulin better. Try the Weight Watchers online program.
- Learn how to count carbs. Carb counting helps you keep track of how many carbohydrates you’re consuming. Setting a maximum amount for each meal helps stabilize blood sugar. Check out this carb counting toolkit and The Complete Guide to Carb Counting from the ADA.
- Learn about the glycemic index (GI). Not all carbs are created equal. The GI measures how much different carbs affect blood sugar. Foods with a high GI rating affect blood sugar more than those with a low rating. You can search for low GI foods through glycemicindex.com.
- Find healthy recipes. Check out this collection of recipes from Diabetic Lifestyle or buy a diabetes cookbook from the ADA at shopdiabetes.com.
- Try an online meal planning tool, like Healthy Plate from the Joslin Diabetes Center.
- Practice portion control. A kitchen food scale will help you measure your portions better.