Several sweeteners share the title of lowest glycemic index, with a GI of effectively zero: stevia, monk fruit, erythritol, and artificial sweeteners like aspartame all register at 0 or 1 on the glycemic index scale. For comparison, regular table sugar (sucrose) has a GI of 65. The real differences between these zero-GI options come down to taste, digestive tolerance, and how they behave in cooking.
How Sweeteners Rank by Glycemic Index
The glycemic index measures how quickly a food raises blood sugar on a scale of 0 to 100, with pure glucose at the top. Here’s how common sweeteners stack up:
- Erythritol: 0 to 1
- Stevia: less than 1
- Monk fruit: 0
- Artificial sweeteners (aspartame, sucralose): 0 to 1
- Mannitol: approximately 2
- Sorbitol: 4 to 9
- Xylitol: 7 to 13
- Maltitol: approximately 35
- Sucrose (table sugar): 65
The gap between these sweeteners matters. Erythritol, stevia, and monk fruit are all functionally at zero, meaning they cause no measurable rise in blood glucose. Xylitol, often used in sugar-free gum, still has a low GI but is not truly zero. Maltitol, found in many “sugar-free” candy bars and chocolates, sits at around 35, which is low compared to sugar but can still produce a noticeable blood sugar spike if you eat enough of it.
Zero-GI Natural Sweeteners
If you’re looking for the lowest possible glycemic impact from a natural source, three options stand out: stevia, monk fruit, and erythritol.
Stevia is extracted from the leaves of the Stevia rebaudiana plant and is 200 to 300 times sweeter than sugar. Because you need so little to sweeten food, it contributes essentially no calories or carbohydrates. There’s also some evidence that stevia may increase insulin production slightly, which could help lower blood sugar rather than raise it. The main drawback is taste. Many people detect a bitter or licorice-like aftertaste, especially at higher concentrations.
Monk fruit sweetener comes from a small melon native to Southeast Asia. Its sweetness, roughly 100 to 250 times that of sugar, comes from compounds called mogrosides. These pass through your digestive system without being absorbed in the stomach or small intestine, which is why monk fruit adds zero calories and has no effect on blood glucose. Once mogrosides reach the colon, gut bacteria break them down and may even promote the growth of beneficial bacteria like Bifidobacterium and Lactobacillus. Monk fruit tends to have a cleaner taste than stevia, though some people notice a slight fruity aftertaste.
Erythritol is a sugar alcohol, but it behaves differently from others in its category. About 90% of it is absorbed in the small intestine and excreted unchanged through urine, meaning very little reaches the colon. This gives it two advantages: a GI of 0 to 1, and far less digestive discomfort than other sugar alcohols. It provides about 70% of sugar’s sweetness with roughly 0.2 calories per gram (compared to sugar’s 4 calories per gram). Erythritol also adds bulk to recipes in a way that stevia and monk fruit cannot, which is why many baking blends combine erythritol with one of the more intense sweeteners.
Why Some “Low-GI” Sweeteners Are Misleading
Agave nectar is often marketed as a low-glycemic alternative to sugar, and technically its GI is lower than table sugar’s. But that low number is driven by its extremely high fructose content. Fructose doesn’t spike blood glucose quickly because it’s processed by the liver rather than entering the bloodstream directly. That doesn’t make it healthy. The American Diabetes Association has pointed out that agave is still sugar, still raises blood glucose over time, and is far from a healthy choice. The same logic applies to any sweetener marketed as “low GI” purely because of its fructose ratio.
Maltitol is another common offender. It appears in sugar-free chocolates, protein bars, and baked goods, and manufacturers sometimes label products containing it as “no sugar added.” But at a GI of roughly 35, maltitol produces a meaningful blood sugar response, especially in the large quantities found in a full candy bar or serving of cookies. If blood sugar control is your goal, check ingredient labels for maltitol and treat it differently from truly zero-GI alternatives.
Newer Options Worth Knowing About
Allulose is a rare sugar that’s been gaining popularity in packaged foods and baking products. It tastes and behaves very much like sugar (it browns, dissolves, and provides bulk) but your body absorbs and excretes most of it without metabolizing it for energy. A clinical study published in BMJ Open Diabetes Research & Care found that adding 7.5 to 10 grams of allulose to a dose of sugar significantly reduced blood glucose levels at 30 minutes compared to a placebo, with the effect increasing at higher doses. Allulose doesn’t have a widely published GI number yet, but its blood sugar impact is near zero.
Tagatose is another rare sugar with about 90% of sugar’s sweetness but a fraction of its glycemic impact. Research has shown that consuming tagatose significantly blunts the rise in blood glucose after eating, even in people with type 2 diabetes, without significantly affecting insulin levels. It also acts as a prebiotic, feeding beneficial gut bacteria. The European Food Safety Authority has confirmed that doses of 7.5 grams or more per meal help balance blood glucose. Tagatose is less widely available than other sweeteners but shows up in some specialty products and sugar-free foods.
Choosing Based on How You’ll Use It
All of the zero-GI sweeteners are equally “zero” when it comes to blood sugar, so the best choice depends on what you’re actually doing with it. For sweetening coffee or tea, liquid stevia or monk fruit drops work well because you need only a tiny amount. For baking, erythritol or allulose are better choices because they provide the bulk and texture that concentrated sweeteners can’t. Erythritol can crystallize and create a cooling sensation in some recipes, while allulose behaves more like real sugar in terms of moisture and browning.
Many commercial products blend two or more of these sweeteners to balance taste, texture, and cost. A common combination is erythritol with monk fruit or stevia, which provides bulk from the erythritol and intense sweetness from the concentrated sweetener. These blends maintain a GI of zero while tasting closer to sugar than any single sweetener alone.
Digestive tolerance is worth considering too. Sugar alcohols other than erythritol (xylitol, sorbitol, maltitol) are not fully absorbed in the small intestine, which means they ferment in the colon and can cause bloating, gas, or diarrhea in some people. Erythritol largely avoids this problem. Stevia, monk fruit, and allulose also cause minimal digestive issues for most people at normal serving sizes.