In recent years, there has been a surge of public interest in blood glucose monitoring, thanks in part to high-profile health influencers such as Jessie Inchauspé—widely known as the “Glucose Goddess”— and the growing accessibility of continuous glucose monitors (CGMs).
Once a tool reserved almost exclusively for people with diabetes, CGMs are now worn by health-conscious individuals looking to optimise energy levels, mood, weight, and long-term metabolic health.
While this data has fueled positive behavior changes and a newfound appreciation for metabolic health, it has also introduced some confusion—particularly around the meaning and implications of blood glucose “spikes.”
It’s time to re-frame the narrative.
Not all spikes are problematic.
In fact, a rise in blood glucose after eating is a normal, healthy, and expected physiological response.
The real issue lies not in the rise itself, but in what comes after: how quickly and efficiently the body returns blood glucose to baseline.
Understanding this distinction is essential for interpreting glucose data meaningfully and for making sound decisions about diet and lifestyle.
After we eat carbohydrates, whether from fruit, bread, pasta, dairy or even legumes, our bodies break them down into glucose, which enters the bloodstream.
This causes blood glucose levels to rise. In response, the pancreas releases insulin, a hormone that allows gluocse to enter the cell helps cells for energy or storage, thereby reducing the amount of glucose circulating in the blood.
This post-meal rise in glucose is commonly referred to as a “spike.”
On CGM graphs, it appears as a sharp uptick, sometimes triggering alarm among users who associate it with poor metabolic control. But context is everything.
A spike after eating is not inherently bad.
In fact, the absence of a rise might indicate a serious issue—such as an inability to absorb nutrients, insufficient carbohydrate intake, or a malfunction in glucose sensing.
It’s not the Spike, it’s the Slope
What truly matters is how long glucose stays elevated.
This is where the concept of the “area under the curve” (AUC) becomes important.
The AUC refers to the total amount of time and degree to which blood glucose is elevated after a meal.
A rapid return to baseline suggests that insulin sensitivity is high and metabolic function is robust.
A slow return or sustained elevation may signal insulin resistance, a precursor to type 2 diabetes and other chronic conditions.
For example, eating a banana might cause a sharp, short-lived spike, while eating a donut might cause a similar spike followed by a long tail of elevated glucose levels.
The problem isn’t necessarily the height of the peak; it’s the breadth of the curve.
The longer glucose remains elevated, the more stress is placed on insulin-producing cells and the greater the risk of glycation (the mechanism of diabetic tissue damage) and inflammation.
Fruits and other whole foods are often unfairly demonised in this new glucose-aware landscape. While they are rich in natural sugars and carbohydrates, they also come packaged with fiber, water, vitamins, and polyphenols, components that moderate glucose response and offer numerous health benefits.
Yes, fruit can cause a measurable glucose rise. That’s expected.
But in healthy individuals, this rise is typically short-lived and followed by a prompt return to baseline—especially when the fruit is consumed as part of a balanced meal.
This highlights the need for nuance. Not all carbohydrates are created equal. The source of the carbohydrate, its processing level, and the context in which it’s consumed (e.g., with protein or fat) all influence its metabolic impact.
If we’re going to point fingers, we should be directing attention toward ultra-processed foods (UPFs), heavily engineered products with refined carbohydrates, added sugars, emulsifiers, and little nutritional value.
These foods are designed to be hyper-palatable and are digested and absorbed rapidly, often causing exaggerated and prolonged glucose responses.
But the more insidious issue is what happens after the spike.
These foods often induce a reactive hypoglycemia—a steep drop in blood sugar following the initial spike, as the body overcompensates with insulin.
This crash can lead to cravings, fatigue, irritability (“hangry”), and a subsequent cycle of seeking another quick fix.
In this cycle, the body is repeatedly tasked with raising blood sugar levels after they drop too low, a chronic stressor on the endocrine system.
Over time, this dysregulation of glucose homeostasis can erode metabolic resilience and increase the risk of obesity, insulin resistance, and cardiovascular disease.
Blood sugar dysregulation doesn’t just impact metabolism, it affects the entire stress response system.
Every time blood glucose falls below optimal levels, the body initiates a counter-regulatory response, releasing hormones like cortisol and adrenaline to bring it back up.
While this is a normal survival mechanism, repeated activation due to dietary choices can lead to chronically elevated stress hormone levels, impaired sleep, and increased systemic inflammation.
This is why the constant consumption of ultra-processed carbohydrates is more harmful than occasional, transient spikes from whole foods like fruits or starchy vegetables.
UPFs not only cause larger AUCs but also force the body into a metabolic rollercoaster that undermines long-term health.
Check out the difference on AUC between a banana and a doughnut and note the glucose levels drop BELOW normal.
Green (Meal A: Banana) shows a quick spike and return to baseline—small AUC, indicating efficient glucose regulation.
Red (Meal B: Doughnut) shows a higher and prolonged spike with a crash—larger AUC, indicating metabolic stress.
For those using continuous glucose monitors, it’s important to approach the data with an informed and compassionate lens. Here are a few guiding principles:
Don’t fear every spike. Instead, look at patterns. Is your glucose consistently elevated? Does it take a long time to return to baseline?
Prioritize whole foods. Choose minimally processed carbohydrates that come with fiber and nutrients.
Balance your meals – Including protein, fat, and fiber slows down glucose absorption and moderates the rise, especially when you eat the veggies and protein first, carbs last.
Check the graph below, note the lack of spike when the vegetables/protein is eaten first vs carbs first, same meal, massive difference.
Use apple cider vinegar with your food, add 1-2 tbsp in a little water before a meal.
Be mindful of timing and activity, a post-meal walk can significantly improve glucose clearance.
Rather than chasing flat glucose lines, aim for flexibility and resilience. That means eating nutrient-dense foods, limiting ultra-processed carbohydrates, and supporting your body’s ability to handle and recover from normal, healthy fluctuations.