Here's How To Tell If Your Blood Sugar Is Spiking & If It's Crashing

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Keeping your blood sugar levels balanced can have an enormous impact on how you feel—and may even protect you from various lifestyle diseases. But in order to keep your blood sugar balanced, you have to know when it’s imbalanced. 

The most accurate way to tell if your blood sugar is spiking is through continuous glucose monitoring (a wearable device that tracks blood sugar automatically), but your body may also give you some physical signs when your blood sugar gets too high.

By current standards, the normal blood sugar range for a non-diabetic person is between 70 to 140 mg/dL (or milligrams per decilitre). A spike is any deviation or rise from that baseline blood sugar, explains functional nutritionist Norah Candito, M.S, R.D. 

Stress can cause blood sugar spikes, but they most often happen in response to eating a carbohydrate-rich meal. “The body is receiving energy from an outside source, and until that energy is distributed throughout the body (with the help of insulin), blood sugar remains elevated,” says Candito. 

While all carbohydrates raise your blood sugar to some degree, high-glycemic carbohydrates, like breakfast cereals, processed white breads, sugar-sweetened beverages, and other sweets are typically to blame for blood sugar spikes.

Blood sugar spikes are bound to happen once in a while, but problems can arise if they become a regular occurrence. 

“These dramatic spikes and subsequent crashes are not good for health because it places stress on the body. Over time, this can put individuals at risk for type 2 diabetes, among other health issues (high blood pressure and cardiovascular disease),” says Candito.

On a recent mbg podcast, biochemist Jessie Inchauspe, author of Glucose Revolution: The Life-Changing Power of Balancing Your Blood Sugar explains that regular blood sugar spikes can have many other long-term health effects, including:

So, how can you tell if your blood sugar is spiking? In the short term, Inchauspe says you might feel really hungry (even right you eat), experience an energy slump after a meal, or have cravings for sweets. Blood sugar spikes can also affect your sleep, making it more likely that you’ll toss and turn that night.

“Sometimes people who experience a blood sugar spike may feel ‘buzzy’—a little jittery or anxious, or like they’re a bit out of balance,” adds Wendy Bazilian, DrPH, RDN. She says that increased thirst, headaches, inability to focus, confusion, and blurred vision can also signal a blood sugar spike, but these signs usually only occur if your blood sugar is elevated above a normal range and often warrant a check in with your healthcare provider. 

In summary, blood sugar spike symptoms can include:

If your blood sugar is within normal ranges, what you’re more likely to feel are the symptoms of a blood sugar crash, which is the drop in blood sugar that follows a blood sugar spike. 

When your body detects a rise in blood sugar, it sends out insulin, which helps glucose enter your cells so your body can use it as energy. Insulin also signals the liver to convert any remaining glucose into glycogen and store it for later. 

The result of this insulin response is a subsequent blood sugar crash, which, according to Cardito, can cause:

While it’s normal for your blood sugar to go up to some degree after a meal, you want to avoid these more dramatic glucose spikes and crashes as much as possible. Low-carb diets can be a helpful way for some people to manage their blood sugar levels, but if you’re not ready (or willing) to go there, you have other options, too.

Inchauspe says one way to manage blood sugar is by "putting clothing on your carbs.” In other words, pair carbs with protein, fiber, or some healthy fats. Doing so can slow down the absorption rate of glucose and help reduce the severity of blood sugar spikes (and resulting crashes).

The order in which you eat your food can also play a role. Inchauspe explains that eating foods in a specific order can reduce the blood sugar spike from that meal by as much as 75%, even when you’re eating the exact same foods. “The correct order is vegetables first, proteins and fats second, starches and sugars last,” she says.