Sugar alcohols are generally a safer sweetener choice for people with diabetes than regular sugar. They raise blood glucose less, contain fewer calories, and are partially absorbed by the body. But not all sugar alcohols are equal, and some come with side effects or emerging concerns worth knowing about.
How Sugar Alcohols Affect Blood Sugar
Sugar alcohols break down slowly in your gut, and your body only absorbs part of their carbohydrates. This prevents the sharp blood sugar and insulin spikes that regular sugar causes. For context, table sugar (sucrose) has a glycemic index of 65. Here’s how common sugar alcohols compare:
- Erythritol: GI of 1
- Mannitol: GI of 2
- Isomalt: GI of 2
- Sorbitol: GI of 4
- Xylitol: GI of 12
- Maltitol: GI of 35
Erythritol barely registers on the glycemic index at all. Maltitol is the outlier. At a GI of 35, it still lands well below table sugar, but it’s high enough to nudge your blood glucose noticeably, especially in larger portions. If you’re checking labels on “sugar-free” candy or protein bars, maltitol is one of the most common sugar alcohols used, and it’s the one most likely to affect your readings.
Studies comparing maltitol directly to sugar in baked goods found it produced a lower blood glucose response, a lower glycemic index, and a lower insulin response. So it’s still an improvement over sugar. But if you’re tightly managing your levels, maltitol deserves more caution than erythritol or xylitol.
Counting Carbs With Sugar Alcohols
Sugar alcohols show up on the Nutrition Facts panel under total carbohydrates. If you use carb counting to manage your diabetes, the UCSF Diabetes Teaching Center recommends a simple rule: subtract half the grams of sugar alcohol from the total carbohydrate count. So a product with 29 grams of total carbs and 18 grams of sugar alcohol would count as 20 grams of effective carbohydrate (29 minus 9).
This “half rule” works because most sugar alcohols are only partially absorbed. Erythritol is actually absorbed even less than that, so this formula is conservative in its case. Checking your blood glucose before eating a sugar alcohol product and again 1.5 to 2 hours afterward is the most reliable way to see how your body responds to a specific product.
Digestive Side Effects
The biggest practical downside of sugar alcohols is their laxative effect. Because they aren’t fully absorbed, they draw water into the intestines. Most adults can tolerate roughly 20 to 50 grams per day before bloating, gas, or diarrhea set in, though the exact threshold varies by the specific sugar alcohol. People with irritable bowel syndrome tend to hit that threshold much sooner.
Erythritol is the best tolerated because it’s absorbed in the small intestine and excreted through urine rather than fermenting in the colon. Sorbitol and maltitol are more likely to cause digestive trouble at moderate doses. If you’re new to sugar alcohol products, starting with small amounts and increasing gradually helps you find your personal tolerance level.
The Erythritol Heart Risk Question
Erythritol has the gentlest effect on blood sugar and digestion, which made it the most popular sugar alcohol for years. But research published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology raised a flag. In large observational studies across both US and European populations, higher fasting blood levels of erythritol were associated with increased risk of heart attack, stroke, or death over three years.
A follow-up interventional study tested what happens after a single 30-gram dose of erythritol in healthy volunteers. Blood levels of erythritol surged more than 1,000-fold, and platelet activity increased in every participant tested. Platelets are the blood cells responsible for clotting, and heightened platelet reactivity can raise the risk of dangerous clots. The researchers found that erythritol enhanced the release of chemical signals that promote clot formation.
This doesn’t mean erythritol is definitively dangerous. Thirty grams is a substantial dose (roughly the amount in a couple of heavily sweetened drinks), and these findings are still being studied. But for people with diabetes, who already face elevated cardiovascular risk, this research is worth knowing about. Moderation is reasonable until the picture becomes clearer.
Calories and Weight Management
Regular sugar contains about 4 calories per gram. Sugar alcohols range from 0 to 2 calories per gram, roughly half or less. Xylitol, for example, has 2.4 calories per gram. Erythritol is essentially calorie-free. This caloric reduction can support weight management, which directly affects blood sugar control over time.
That said, “sugar-free” products made with sugar alcohols aren’t calorie-free products. They still contain fats, starches, and other carbohydrates. Eating large quantities because a label says “sugar-free” can still lead to excess calorie intake and blood sugar fluctuations.
A Bonus for Dental Health
People with diabetes are at higher risk for gum disease and tooth decay. Xylitol offers a specific advantage here: it actively inhibits the growth of the bacteria most responsible for cavities. Clinical tests show that consuming xylitol-sweetened products between meals significantly reduces new cavity formation, even in people who already brush and floss regularly. Xylitol gum and mints also stimulate saliva flow, which helps repair damaged tooth enamel. This makes xylitol a particularly useful sugar substitute for people managing diabetes.
Which Sugar Alcohols Are Best for Diabetes
If your main goal is minimal blood sugar impact, erythritol and xylitol are the strongest choices. Erythritol has virtually no glycemic effect, and xylitol’s GI of 12 is still very low. Sorbitol, mannitol, and isomalt all cluster in the single digits and are reasonable options. Maltitol, at a GI of 35, is the least ideal for tight glucose management, though still meaningfully better than sugar.
In practice, you often don’t get to choose which sugar alcohol is in a product. Reading ingredient lists helps. If maltitol is the primary sweetener, treat the product more cautiously in your carb counting. If erythritol or xylitol is listed, you have more flexibility. And regardless of type, keeping portions moderate avoids both the digestive side effects and the carbohydrate load that can accumulate when sugar-free products are eaten freely.