Not all “sugar-free” sweeteners are equal. Some have zero glycemic impact. Others will spike your blood sugar while the label still says zero sugar. We rate each one by its real-world CGM impact so you can shop with confidence.
Allulose is a rare sugar found naturally in small amounts in figs and raisins. Unlike table sugar, it is not metabolized for energy — roughly 70% is absorbed in the small intestine and excreted unchanged in urine, with the remainder passing through undigested. Your blood glucose does not rise after consuming allulose, making it essentially invisible to your CGM. It also caramelizes and browns like real sugar, making it the gold standard for diabetic baking — cookies, caramel, and fudge all behave correctly.
Sugar Rebel's Verdict: Sugar Rebel's top pick. Zero glycemic impact, bakes like sugar. If a product uses allulose as its primary sweetener, it earns our strongest seal of approval.
Monk Fruit (Lo Han Guo)
CGM: GreenGI: 0
Monk fruit extract comes from the Luo Han Guo fruit grown in southern China. The sweetness comes from mogrosides — antioxidant compounds, not sugars. It contains zero calories, zero carbohydrates, and has a glycemic index of zero. It does not affect insulin levels. Monk fruit is 100–250x sweeter than sugar, so manufacturers use very small amounts. It has been used in traditional Chinese medicine for centuries and is FDA-classified as generally recognized as safe (GRAS).
Sugar Rebel's Verdict: Excellent choice. Zero glycemic impact, zero calories, long safety record. Watch out for blends that combine monk fruit with maltodextrin as a carrier — the maltodextrin negates the benefit entirely.
Erythritol
CGM: YellowGI: ~0.2
Erythritol is a sugar alcohol (polyol) found naturally in grapes and fermented foods. Unlike maltitol or sorbitol, roughly 90% of erythritol is absorbed in the small intestine before it reaches the colon — this is why it causes far less GI distress than other sugar alcohols. Its glycemic index is approximately 0.2, meaning it has minimal but non-zero blood glucose impact. Some individuals still report a mild glucose response, particularly at higher doses (>50g). A 2023 observational study (Hazen et al., Nature Medicine) found an association between elevated plasma erythritol and cardiovascular events — though this study measured endogenous erythritol produced by the body during metabolic stress, not dietary intake. The relationship is still being studied.
Sugar Rebel's Verdict: Generally safe for most diabetics at normal serving sizes. Preferred over maltitol and sorbitol. If you notice even small glucose spikes on your CGM, consider switching to allulose or monk fruit.
Maltitol is the most commonly used sugar alcohol in 'sugar-free' candy, chocolate, and baked goods — and it is the one most likely to spike your blood sugar. Its glycemic index is 36, roughly half that of table sugar (65), but this is NOT safe for diabetics. A single serving of maltitol-sweetened chocolate can raise blood glucose by 30–50 mg/dL in type 2 diabetics. Manufacturers use maltitol because it's cheap, has a texture similar to sugar, and technically lets them print 'sugar-free' on the label. Sugar alcohols are not required to be counted as sugar on nutrition labels in many jurisdictions. The label says zero sugar. Your CGM disagrees.
Sugar Rebel's Verdict: AVOID. This is the most common trap in 'diabetic-friendly' candy aisles. Check ingredients before buying anything labeled sugar-free.
Sorbitol has a lower glycemic index than maltitol (~9) but is notorious for causing severe gastrointestinal distress at doses above 10–20g. It is poorly absorbed in the small intestine and ferments in the colon, causing bloating, cramping, and diarrhea. It is common in sugar-free gum, mints, and some liquid medications. While the glycemic impact is lower than maltitol, the GI side effects make it impractical and uncomfortable for regular consumption.
Sugar Rebel's Verdict: Avoid in any meaningful quantity. Even if the blood sugar impact is manageable, the digestive consequences are not worth it.
Xylitol is a sugar alcohol with a GI of approximately 13 — lower than maltitol but not negligible. It does cause a moderate insulin response in some people. It is well-known for dental benefits (it inhibits cavity-causing bacteria) and is widely used in gum and dental products. However, it causes GI distress in large amounts, and it is extremely toxic to dogs — a real risk if you have pets. Xylitol from birch is generally considered higher quality than corn-derived xylitol, though the metabolic effects are the same.
Sugar Rebel's Verdict: Acceptable in small amounts (dental gum), but not a top pick for food products. Better options exist.
Maltodextrin
CGM: RedGI: 85–105
Maltodextrin is not a sweetener — it is a highly processed starch used as a filler and carrier. Its glycemic index is 85–105, higher than table sugar. It is commonly used as a carrier for powdered monk fruit and stevia extracts, which means a product can advertise 'sweetened with monk fruit' while spiking your blood sugar via the maltodextrin carrier. It is also used in protein powders, pre-workouts, and 'sugar-free' syrups. Always check the full ingredient list.
Sugar Rebel's Verdict: AVOID. High GI filler hiding in 'sugar-free' products. Its presence in a monk fruit or stevia product makes that product unsafe for diabetics.
How We Rate CGM Impact
Green — Safe for Diabetics
Yellow — Use With Caution
Red — Avoid
CGM impact ratings are based on published glycemic index research, clinical studies, and community-reported continuous glucose monitor readings. Individual responses vary. Always verify with your own CGM data.