Why it hits so hard
Evidence level: established
Regular cola typically contains about 10.6 g of sugar per 100 ml. For 330 ml that’s roughly 35 g of sugar. Coke Zero (zero sugar), by contrast, is declared as 0 g sugar / 100 ml. In practice that means: you expect “0” but get “~35 g” – and if you don’t expect it, that can throw you completely out of rhythm. It cost me an evening on the cruise ship myself.
Immediate tactics when you suspect it
- Stop the drink (don’t “finish it up”).
- Ask for a new drink only in the original can/bottle (open it yourself).
- Check CGM/blood sugar closely (finger-prick to cross-check if needed).
- Movement can dampen the peak (e.g. 10–20 minutes of brisk walking).
- If you use insulin: no gut-feeling insulin adjustment – act according to your agreed correction scheme instead.
How can you check drinks “for sugar” (realistically, without a lab)?
Three ways to check a drink for sugar on the go. Option A, a Brix refractometer, is the most sensible: it measures dissolved sugar as degrees Brix; regular cola is around 10 to 11, Zero near 0. Option B, glucose test strips, only as a rough indicator, because they do not capture all sugar types and are often not validated for drinks. Option C, a blood glucose meter, is not advised, because it is calibrated for blood, not soft drinks.
Checking drinks on the go: 3 options
A
Brix refractometer – the most sensible
Measures sugar as °Brix. Regular cola ~10–11 °Brix, Zero near 0. Fast, repeatable.
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B
Glucose test strips – rough indicator only
Error-prone: doesn’t capture all sugar types, often not validated for drinks.
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C
Blood glucose meter – not advised
Calibrated for blood, not soft drinks; can skew readings and ruin strips.
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Option A (most sensible): Brix refractometer. A refractometer measures dissolved substances (including sugar) as °Brix. Regular cola is roughly around ~10–11 °Brix, which matches the typical sugar amount. Zero drinks are near 0 °Brix (practically no sugar). Advantages: fast (1–2 drops), repeatable, independent of the CGM lag – exactly the kind of “plausibility check” that makes sense on the go. Important: let the carbonation off-gas briefly first (shake/let it stand), otherwise the reading is noisier.
Option B: “glucose test strips” for drinks. There are strips meant to detect glucose. In practice this is error-prone, because drinks can contain other sugar types (e.g. sucrose/fructose) and many strips aren’t validated for food/soft drinks. If you do it: only as a rough indicator – I’ll test a few soon.
Option C: measuring the drink with a blood glucose meter. I advise against this: meters/strips are calibrated for blood, not soft drinks. It can skew readings and needlessly ruin the device/strips. A workaround: smear a little drink on the finger above where you measure – you can then cross-validate the values with a second test site.
Key takeaways
- Regular cola: ~10.6 g sugar/100 ml → ~35 g per 0.33 l; Coke Zero: 0 g.
- If you suspect it: stop the drink, open a new one from the original can yourself, check blood sugar.
- Movement (10–20 min brisk walk) can dampen a peak.
- Checking drinks: a Brix refractometer is most sensible; a blood glucose meter for drinks is not advised.
- On insulin: act only by your agreed correction scheme, not “by gut feeling”.
Sources
Sources as of: 21 Jul 2026.
- Sugar content of regular cola (~10.6 g/100 ml) vs. zero variants; general reference. coca-cola.com
- Brix as a measure of dissolved solids (mainly sugar); cola-typical values ~10–11 °Brix. Basis: refractometry. Brix (overview)