Written by
Louise W Lu, PhD, MPH, BMLS
Written/Reviewed by
Alexandra V Goldberg, Registered Dietitian
You might not know this, but a simple, ordinary potato can reveal your blood sugar sensitivity faster than a medical check-up.
A recent study published in Nature Medicine found that people show dramatically different blood sugar responses to the same carbohydrates — and these differences clearly reflect metabolic health.
So, what’s the simplest way to understand your real blood sugar response? Not a glucose drink, not complicated tests — just one standard portion of a potato, ideally steamed or boiled.
After you eat it, how fast your blood sugar rises and how long it takes to come down can serve as your very own “carb tolerance test.”
In this article, I’ll show you why it has to be a potato, why it reveals problems more clearly than rice, bread, or sweet potatoes, and how you can do your own “Potato Blood Sugar Test.”
1. Why Use a Potato to Test Your Blood Sugar Response?
A potato may look completely ordinary, but it is one of the fastest and most accurate foods for revealing how your blood sugar behaves.
That’s because a potato contains almost one primary carbohydrate — starch. No added fat, no protein, no complex grain fibers, and no ingredients that slow digestion.
In other words, a potato is a “clean” test food.
Your body absorbs it quickly, and the blood sugar curve that appears afterwards clearly reflects:
- Your insulin sensitivity
- The speed at which your gut absorbs carbohydrates
- Your efficiency in clearing glucose
- Your overall metabolic flexibility
Put simply, a potato reveals your true blood sugar response. Rice, noodles, bread, and sweet potatoes all contain fibers, fats, or processing differences that “blur” the result and make your body’s reaction harder to read.
In the latest study published in Nature Medicine, researchers found that even when participants ate the exact same potato, their blood sugar peaks and recovery speeds were dramatically different.
If your blood sugar spikes quickly after eating a potato and takes a long time to come down, it often suggests:
- Possible insulin resistance
- Slower glucose clearance
- Higher metabolic stress
- Greater sensitivity to carbohydrates
2. What Does the Nature Medicine Study Tell Us?
You might assume that when people eat the same amount of carbohydrates, their blood sugar responses should look similar. But the latest study published in Nature Medicine revealed something completely different — post-meal blood sugar responses (PPGR) vary dramatically between individuals, and these differences truly matter.
In this study, participants consumed seven standardized carbohydrate foods — including rice, bread, grapes, legumes, and of course, potatoes.
The results surprised even the researchers:
- Some people barely reacted to rice, but had a dramatic spike after eating potatoes
- Some spiked sky-high after bread, but stayed stable with rice
- And some reacted strongly to every carbohydrate they ate
In other words, the same food can produce completely different blood sugar curves in different people. And these differences are not just “individual quirks” — they are strongly linked to your metabolic health.
Researchers also found:
- Those who had the highest spikes after eating the same potato usually had poorer insulin sensitivity
- Their glucose-clearing ability was significantly slower
- And they showed early signs of future metabolic risk (such as prediabetes)
So when you do the “potato test,” what you see is not just a curve — you are seeing your body’s true metabolic capacity.
Put simply — your response to a potato reveals far more about your metabolic health than you might imagine.
3. How to Do a “Potato Blood Sugar Test” by Yourself
To understand how your body reacts to carbohydrates, you don’t need medical equipment or a glucose drink.
All you need is one potato and a basic blood glucose meter (a CGM is great if you have one, but not required).
✔ Step 1: Prepare a Standard-Sized Potato
Choose 100–120 grams of boiled or steamed potato (no oil, no salt, no butter). This “test size” is commonly used in studies and helps create a clear glucose curve.
✔ Step 2: Test While Fasting or 3–4 Hours After a Meal
To avoid interference from your previous meal, make sure your blood sugar is stable. If you’re unsure, measure a quick fasting blood sugar first.
✔ Step 3: Eat the Potato Within 5 Minutes
Do not pair it with any other food or drink (including coffee, milk, juice, or supplements). The goal is to avoid anything that might change the absorption rate.
✔ Step 4: Measure Your Blood Sugar at These Key Times
- 30 minutes after eating
- 60 minutes
- 90 minutes (optional)
- 120 minutes
These checkpoints help you understand:
- How fast your blood sugar rises (speed)
- How high it goes (peak)
- How long it takes to come down (recovery)
✔ Step 5: Compare Your Results and Identify Your Response Type
Simple Interpretation Guide:
- 30 min > 9.0 mmol/L: blood sugar “spikes too fast” — possible reduced insulin sensitivity.
- 60 min still near the peak: slower glucose handling.
- 120 min > 7.8 mmol/L: insufficient glucose clearance.
- Not returning to baseline ±0.5 after 2 hours: more likely insulin resistance.
✔ Step 6: Repeat for 2–3 Days for Consistency
If your results remain high or decline very slowly over multiple tests, your body is sending a clear metabolic warning signal.
And this is the value of the potato test: It’s simple, visual, and accurately reveals your true metabolic state.
Final Reminder:
If you already use a CGM, the potato test will be extremely clear. If you don’t have a glucose meter, consider using a simple finger-prick meter just once — the insights you gain are far more valuable than you might expect.
One potato can tell you whether your body can truly handle carbohydrates.
