The Truth About Glucose “Spikes”

I was recently quoted in this Eating Well article about habits that can “spike” blood sugar. In this blog, get the juicy details that did not make it into the article!

The word “spike” has recently picked up attention as a way to casually describe the elevation of blood glucose, particularly when viewed on a continuous glucose monitoring (CGM) app.

People with type 1 diabetes have always used the term glucose spike as a result of something—that something may have been food, stress, lack of insulin, the dawn effect, or other puzzling element of physiology that causes blood glucose to elevate quickly. This was before CGMs became all the rage.

The manual effort of the old-fashioned finger stick test is more of a conscious process—basically, we go to the trouble of poking our fingers for a reason.

The point of a finger stick test is to answer a question—was my meal insulin dose accurate? Was my blood sugar in range overnight? Is now the right time to workout? The number we see from a single finger stick test can either confirm a choice we made to get that result or it directs us to make another decision.

Tech in diabetes care is awesome. However, it needs to be used wisely. The trend line showing blood glucose patterns on a CGM app has resulted in over-simplifed click-baity comments like “stop the spike” or “flatten the curve”. These misleading messages are NOT helpful and they don’t teach us anything about our bodies

—so let’s get into it.

What exaclty is a blood sugar spike?

A "spike" is merely a visual interpretation of blood glucose popularized by the use of continuous glucose monitors. Unfortunately, the word "spike" is used loosely to imply that any rise in blood glucose should be prevented, but that is not a fact. What is really happening to a person's blood glucose when it rises is much more detailed and should not automatically be labeled as unhealthy. 

Natural rises in blood sugar are normal for people with and without diabetes.

Virtually everything we do requires glucose as an important source of cellular fuel that is always in demand. Glucose is constantly being transported with the assistance of insulin. Glucose is so important that muscles and the liver are capable of storing several days' supply in the form of glycogen. However, the first matter to be aware of is that blood glucose is supposed to rise and fall throughout the day.

People can expect to maintain a healthy blood glucose range that is lowest while asleep (in the fasted state) and a little higher when awake. 

When we eat, our food has an absorption rate that lasts for several hours. Blood glucose rises and typically falls during this time and the rate of absorption is a result of meal composition. If blood glucose rises while eating and continues to rise between meals, it might be time to talk with a dietitian trained in preventing insulin resistance through lifestyle—LIKE ME.  

What about stress?

If blood glucose rises unexpectedly outside of meals, acute moments of stress need to be considered—which are not necessarily unhealthy, e.g. short bursts of strenuous exercise. "Spike" doesn't even come close to accurately describing what occurs during stressful events or the full story behind blood glucose reactivity. 

Natural physiology can raise blood sugar and should always be considered.

Hormones are released when we experience acute moments of stress and not every situation is unhealthy -anaerobic training is one example. Short bursts of power cause hormones to release. In turn, those hormones (cortisol, adrenaline) raise blood glucose and this is a completely normal part of our physiology.

When emotional stress is constant, it becomes chronic and this can lead to health problems over time. A number of external factors can cause blood glucose to elevate -sunburn, dehydration, infection, illness, and medications like steroids.  

In conclusion, a “spike” is never just a “spike”. Studying blood glucose patterns takes time and careful monitoring to make smart decisions. If you find yourself confused about what you see, that’s very common. It’s easy for blood glucose trends to get lost in translation because of all the lifetyle factors to consider.