> ## Content Index
> Fetch the complete content index at: https://the-glucose-field-guide.ghost.io/llms.txt
> Use this file to discover other available public pages before exploring further.

# I was sure Coke Zero would spike me. It did nothing.
- URL: https://the-glucose-field-guide.ghost.io/i-was-sure-coke-zero-would-spike-me-it-did-nothing/
- Published: 2026-10-12T15:00:00.000Z
- Updated: 2026-10-12T15:00:00.000Z
- Description: A can on an empty stomach moved my blood sugar three points, which is noise. The interesting part is what a flat line does not tell you.
- Author: The Glucose Field Guide

| I was wrong again. On Friday I said I had an opinion about what a Coke Zero would do to my blood sugar. My opinion was that it would do something. I had read enough posts claiming that diet soda gets you anyway, through some back door, that I expected a bump. So this morning, 7am, empty stomach, one can. Nothing else. Here is what my glucose monitor recorded for the next two hours… ![Glucose chart. A can of Coke Zero on an empty stomach raised blood sugar 3 points, a nearly flat line. The same can drunk with a banana raised it 52 points, peaking at 30 minutes.](https://storage.ghost.io/c/cf/1c/cf1c5695-50da-4986-90a3-3727fcbc3f0a/content/images/2026/10/glucose-chart-2026-10-12.png) This is one person's experiment, not medical advice. Everyone's body responds differently. Three points. That is not a result. That is my monitor breathing. My blood sugar wanders by more than three points when I stand up too fast. So the first answer is the boring one. On an empty stomach, this can did nothing to me. Why nothing happened Read the can and the answer is right there. Zero calories. Zero carbohydrate. Zero sugar. Your blood sugar goes up when carbohydrate gets broken down into glucose and absorbed. A Coke Zero brings no carbohydrate to break down. In other words, there is nothing in the can for your body to turn into blood sugar. The sweetness comes from three things instead: aspartame, acesulfame potassium, and a little stevia extract. None of them is a sugar, and none of them carries calories your body can use. Meanwhile, the part that caught me out A flat line is easy to misread. The next morning I drank the same can with the banana I tested last week. If the drink were doing anything protective, this was where it would show. 🥤 The can alone +3 0 g carbohydrate 🥤🍌 Same can, with a banana +52 27 g carbohydrate Fifty two points. The exact same number the banana gave me on its own last week. The drink did not add anything. It did not take anything away either. And that is the trap. A zero on the can feels like a zero on the meal, so the thing you bought to go with it stops getting counted. The can is free. The sandwich next to it is not… **Judge the plate, not the glass.**Swapping to a diet drink changes the drink and nothing else. If the meal was going to raise your blood sugar, it still will. **Use the rules that do work.**Vegetables or protein before the carbs. Something with fat alongside. A short walk after. Those moved my numbers. The drink did not. **Watch what the can travels with.**Mine usually arrives with something from the same counter. That is the part worth changing, and it is the part I kept ignoring. The bigger picture, and I am not going to tidy it up A flat line over two hours is a real finding. It is also a small one. In 2022, researchers at the Weizmann Institute ran something more careful than anything I can do in my kitchen. They screened over 1,300 people and found 120 who avoided sweeteners entirely. Then they put them on aspartame, saccharin, stevia or sucralose for two weeks. Two of the four changed how well people handled glucose. Saccharin and sucralose. Aspartame and stevia, the two in my can that they tested, did not show that effect. What made the difference was gut bacteria. The changes tracked each person's own mix of them, and when the researchers moved those bacteria into mice, the mice picked up the same glucose changes. So the effect is real for some sweeteners, in some people. And it does not show up on a two hour chart. This summer a team at Tufts pooled 21 randomised trials and compared sweeteners against water or a placebo. They found higher fasting insulin, and higher HbA1c. HbA1c is the number your doctor uses to see where your blood sugar has been sitting for the last few months. It was the one that started all this for me. Their senior author, Dariush Mozaffarian, put it in a way I keep coming back to. We cannot simply assume these are safe and harmless, he said, and avoiding them where you can looks like the prudent choice. But he also said that if you are replacing several sugary sodas a day, the sweetener is probably the better of the two. The World Health Organization landed somewhere similar in 2023\. It advises against using these sweeteners to control your weight. And it calls that advice conditional rather than firm. The people who drink them are often already worried about their weight, which muddies every long term study of them. "A flat line means the can is not what is raising my blood sugar today. It does not mean the can is doing me good." Here is where I have ended up, for now. If a Coke Zero is standing in for a regular Coke, that is a trade I would take. If it is standing in for water, I am less sure. So is everyone who studies this properly, which is the honest state of it. I still have one in the fridge. I have stopped pretending it is doing me a favour. Tomorrow, what I drink now when I want a soda and do not want either argument. — Stay steady |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |