Blood Sugar Rollercoaster: Why Your Macros Matter

Visualizing How Proteins and Carbohydrates Impact Blood Sugar Levels

Lots of new sensor data from wearable devices allows us detailed access to information about blood glucose levels — the sugar in your blood. By leveraging data collected through these sensors, we can uncover more insights into your health.

This project uses data from a study that tracked glucose and other physiological markers in 12 participants over 10 days. While the study aimed to assess the feasibility of wearable devices in detecting early signs of physiological changes related to prediabetes and hyperglycemia, our project zooms in on a specific aspect of the data. In particular, we focus on the impact of proteins and carbohydrates on blood sugar levels.

What is Blood Sugar and Why Is It Important?

Blood sugar is a measure of the concentration of glucose in your blood. Keeping it steady is essential,and your body produces hormones like insulin to help regulate it. However, glucose levels can fluctuate quite a bit — especially after meals. If glucose levels frequently spike sharply, then your body can get overwhelmed. These blood glucose spikes can lead to a range of issues, including:

  1. Fatigue: A couple hours after having a spike, blood sugar levels can drop sharply, resulting in feelings of fatigue and even irritability.
  2. Vascular damage: Frequent blood sugar spikes can damage the linings of blood vessels, which can lead to nerve, kidney, and heart problems.

In contrast, keeping your blood sugar stable provides a more consistent flow of energy, helping you avoid crashes and feel more balanced throughout the day. That's why understanding what causes these changes is crucial.

Different Meals Can Have Vastly Different Blood Glucose Spikes

As shown in this plot, the red participant's blood sugar levels after eating high-carbohydrate cinnamon rolls differ significantly from the blue participant's response to high-protein turkey wings. This highlights how different foods can impact blood sugar levels.

Different bites, different sugar spikes.

Legend

Participant 11
Meal:
  • 🍩 Cinnamon Rolls
Participant 4
Meal:
  • 🦃 Turkey Wings
What is a Blood Sugar Spike?

Speaking of sugar spikes, it's important we define what a “blood glucose spike” even is. For our purposes, we define a blood glucose spike as the sharp increase in blood sugar that occurs after a meal. Specifically, we calculate it like this:

\[ \text{Spike} = \text{Max Glucose (2 hours after meal)} - \text{Average Glucose (before meal)} \]

That is, using the meal time as a reference point (time = 0), we look at the highest blood glucose value in the 2 hours that follow, and subtract the average blood glucose from the 30 minutes that came before. The result tells us how much a person's blood sugar rose in response to eating.

Units

Also, you may have noticed that blood glucose levels are measured in mg/dL, which stands for milligrams per deciliter. Intuitively, this means we're measuring the amount of glucose (in milligrams) present in a small volume of blood (a deciliter is one-tenth of a liter). In simpler terms, mg/dL tells us how concentrated the sugar is in your bloodstream.

Let's see how well you can predict blood glucose spikes. Below are 3 meals from the study participants, along with their protein and carbohydrate content.

Your Task:

Choose which meal will have the highest glucose spike given the protein and carbohydrate content.

High Carb Meals Are Typically Followed By High Blood Sugar Spikes

As the carbohydrate content of meals increases, we observe a steady and noticeable rise in the corresponding post-meal blood sugar spikes.

This supports the intuitive idea that meals higher in carbohydrates are consistently linked to higher blood sugar spikes. There's a positive correlation between carbohydrate content and average glucose spike values across the meals.

You can hover over each bar to examine the exact average glucose spike value as well as the meal count for that bin.

High Protein Meals Have Less Pronounced Blood Sugar Spikes than High Carb Meals

We observe an upward trend between protein content and glucose spikes, though this trend is less pronounced than the one we saw with carbohydrates.

However, we can't immediately conclude that protein is directly orrelated with blood sugar spikes. In these meals, the protein content and carbohydrate content are positively correlated (r = 0.43), likely because calorie-dense meals tend to contain higher amounts of both protein and carbohydrates.

As a result, the positive trend between protein levels and blood sugar spikes may be influenced by the confounding effect of carbohydrates.

To better understand the true impact of protein on blood sugar spikes, we need to examine the data more closely.

First, we apply thresholds: meals with at least a moderate amount of protein (above the 34th percentile) are shown in green, while those with high carbs (above the 75th percentile) are shown in red.

Because protein and carbs are correlated, both meal types end up with similar average carb content — but very different levels of protein. This helps us control for carbs and isolate how protein affects blood sugar.

Next, we bring in time. Now you can see how glucose levels actually change over the two hours after a meal.

The result? We re-affirm our previous conclusion that higher carbohydrates have higher blood sugar spikes.

And when protein levels are similar, both lines have a similar shape — the "flatness" doesn't change much.

Now, we flip the script. This time, we control for carbs and focus on how protein affects glucose response.

After accounting for carbohydrates, we find the opposite of our impression from the above bar charts!

Surprisingly, the final glucose level of the high-protein meals is elevated, but its glucose spike is actually flatter than the low-protein meal. Since the high-protein line is flat, we can see that it provides a steadier, more consistent stream of a similar amount of energy.

Overall, this supports the idea that more carbs lead to bigger spikes. But pairing carbs with protein can help flatten those changes. According to the Joslin Diabetes Center, protein can slow down how fast your body digests carbs — leading to a steadier release of energy instead of a quick spike.

🫵 Now it's your turn to explore!

Use the sliders to adjust the minimum protein and carb thresholds and see what happens.

Just keep in mind: Protein and carbs tend to increase together, so raising one may also raise the other on average.

Average Blood Sugar Change After High Carb and High Protein Meals

Minimum Carbohydrates Percentile
20g
Minimum Protein Percentile
10g
High Carb Meals
0
Average Carb Content
0
Average Protein Content
0
High Protein Meals
0
Average Carb Content
0
Average Protein Content
0