Sugar alcohols and diabetes — the carb-counting gray zone

Sugar alcohols in diabetes food labels are the source of more carb-counting confusion than almost any other ingredient category. They appear in the “Total Carbohydrates” section of the Nutrition Facts panel, immediately beneath dietary fibre, typically listed as “Sugar Alcohols Xg.” They are also the basis of the “net carbs” calculation popularised by low-carb product marketing: Total Carbohydrates minus Dietary Fibre minus Sugar Alcohols. The problem is that this calculation treats all sugar alcohols as metabolically inert — and they are not. Erythritol has essentially zero caloric value and negligible blood glucose impact (GI = 0). Xylitol provides 2.4 kcal/g and has a modest glycemic impact (GI = 13). Maltitol — the most commonly used sugar alcohol in commercially produced “sugar-free” chocolate, cookies, and candies — provides 2.1 kcal/g and has a glycemic index of 36, which is not negligible in a person with diabetes eating a 50-gram serving of “sugar-free” chocolate. Per the American Diabetes Association, people with diabetes should count approximately half the sugar alcohol grams as carbohydrate for most polyols, except erythritol (count as zero) and glycerol (count as full carbohydrate). Getting this right changes the carb count on a typical “diabetic-friendly” protein bar by 5–12 grams — a meaningful difference over the course of a day. For the broader question of net carbs versus total carbs and which to count, the sugar alcohol adjustment is one component of a larger calculation framework.

The six main sugar alcohols — and their glycemic indices compared

Sugar alcohols — technically called polyols — are a class of carbohydrate-derived sweeteners used in foods marketed as sugar-free, keto-friendly, or diabetic-appropriate. The name “alcohol” refers to a chemical structure, not ethanol content; they are safe for people who abstain from alcohol. Their key characteristic is partial absorption in the small intestine: unlike glucose or sucrose, polyols are not fully taken up, which reduces their caloric value and blunts their blood glucose impact. But partial is not zero.

Erythritol (GI = 0, 0.2 kcal/g): the safest sugar alcohol for diabetes management. Erythritol is a 4-carbon polyol that is absorbed rapidly and completely in the small intestine — approximately 90% is absorbed — but it is not metabolised. It passes unchanged into urine. This is why it produces no blood glucose or insulin response. Count: zero carbohydrate, regardless of quantity.¹ Erythritol is used in Monkfruit-based sweeteners, many stevia-blended products, and some keto chocolate brands.

Xylitol (GI = 13, 2.4 kcal/g): found in sugar-free gum, mints, and some baked goods. Xylitol has a modest glycemic impact — a GI of 13 compared to glucose’s 100 — because only 50–60% is absorbed, with the remainder fermented in the large intestine. Count: half the grams as carbohydrate.² Notably, xylitol is toxic to dogs at doses as low as 0.1 g/kg body weight; households with pets should store xylitol-containing products carefully.

Sorbitol (GI = 9, 2.6 kcal/g): common in sugar-free sweets, dried fruits, and some medications. Sorbitol has similar absorption characteristics to xylitol. Count: half the grams.²

Lactitol (GI = 6, 2.0 kcal/g): used in some sugar-free chocolates and baked goods. Very low GI, similar counting rule. Count: half the grams.

Isomalt (GI = 9, 2.0 kcal/g): used in sugar-free hard candy, decorative confections, and pharmaceutical coatings. Count: half the grams.

Maltitol (GI = 36, 2.1 kcal/g): the most problematic sugar alcohol for diabetes management. A GI of 36 is higher than most fruits and substantially higher than the other polyols. Count: half to two-thirds, erring toward two-thirds for portions above 20 g.¹ Maltitol is widely used because it mimics the texture and mouthfeel of sucrose — it melts similarly, produces similar crystallisation, and allows “sugar-free” products to closely approximate the sensory experience of the real thing. That functional advantage is precisely what makes it so common and so dangerous for diabetes label-reading.

How to read a nutrition label with sugar alcohols — step by step

The FDA requires that sugar alcohols be listed as a subcategory under Total Carbohydrates when the claim “sugar-free” or “no sugar added” appears on the label. When no such claim is made, listing is optional. “Net carbs” is not an FDA-standardised term — it is a marketing convention with no regulatory definition, and its calculation varies by manufacturer.³

Worked example 1: a popular low-carb protein bar. Nutrition Facts panel shows: Total Carbohydrates 22 g; Dietary Fibre 9 g; Sugar Alcohols 10 g; Sugars 2 g. The manufacturer’s “net carbs” claim: 22 − 9 − 10 = 3 g net carbs. The diabetes-correct count: 9 g fibre = 0 carb; 10 g sugar alcohol — check the ingredient list to identify which polyol. Ingredient list shows “maltitol syrup” as the primary sweetener. At two-thirds counting: 10 × 0.67 = 6.7 g from sugar alcohol. Plus 2 g actual sugars. Plus the non-fibre, non-polyol carbohydrate (22 − 9 − 10 = 3 g base carb). Total: 3 + 6.7 + 2 = 11.7 g carbohydrate — nearly four times the “net carbs” figure on the label.

Worked example 2: a sugar-free chocolate (50 g bar). Total Carbohydrates: 38 g; Fibre 3 g; Sugar Alcohols 32 g; Sugars 0 g. Ingredient list: maltitol as the primary sweetener. Manufacturer net carbs: 38 − 3 − 32 = 3 g. Diabetes-correct count: 32 g maltitol × 0.67 = 21.4 g. Plus 3 g base carb (38 − 3 − 32). Total: 24.4 g carbohydrate — a clinically significant amount for a product positioned as “safe for diabetics.”

Worked example 3: low-carb ice cream (half-cup serving, 70 g). Total Carbohydrates: 18 g; Fibre 4 g; Sugar Alcohols 10 g; Sugars 2 g. Ingredient list shows erythritol as the primary sweetener. Manufacturer net carbs: 4 g. Diabetes-correct count: 10 g erythritol = 0; 4 g fibre = 0; 2 g sugars + 2 g base carb = 4 g carbohydrate — in this case, the net carbs figure is accurate because erythritol is genuinely not counted.

The practical lesson: identify the specific polyol before applying any counting rule. “Sugar alcohols” as a generic category is not informative enough.

Maltitol — the sugar alcohol that isn’t really “sugar-free”

Maltitol deserves a dedicated section because its prevalence and its GI of 36 make it the most clinically consequential miscount in commercial sugar-free products.

A GI of 36 places maltitol solidly in the low-glycemic range — below white bread (GI ~70) and sucrose (GI ~65), but above most polyols by a factor of 3–5. In practice, this means that a 50 g serving of maltitol-sweetened “sugar-free” chocolate raises blood glucose at roughly half the rate of an equivalent serving of regular chocolate. Not zero — half. For a person with Type 1 diabetes using an insulin-to-carb ratio of 1:10, using the net-carbs figure (3 g) rather than the correct figure (24 g) means injecting approximately 2.1 units too little insulin — enough to produce a 2–4 hour hyperglycemia of 180–250 mg/dL.¹

How to identify maltitol-heavy products: the ingredient list ranks ingredients by weight. If maltitol, maltitol syrup, or hydrogenated glucose syrup appears first or second in the sweetener list, the product likely contains ≥30 g of maltitol per 100 g. Sugar-free chocolate, caramel, toffee, and “keto brownie” products are the highest-frequency offenders. Products that combine maltitol with erythritol are significantly safer — the erythritol counts zero and the blended product typically has a lower GI than pure maltitol.

The sugar-free label creates a systematic misperception. Per a 2020 study in Nutrition & Diabetes, people with Type 1 diabetes who selected “diabetic-friendly” packaged sweets showed post-meal glucose excursions averaging 58% larger than their pre-selection estimate — a mismatch attributable largely to the maltitol content of the chosen products.⁴

Erythritol — the one sugar alcohol that genuinely doesn’t count

Erythritol’s metabolic inertness is well-established across multiple controlled clinical studies. In a crossover study comparing erythritol and sucrose, blood glucose and insulin responses after 36 g erythritol were statistically indistinguishable from water — compared to a 30 mg/dL glucose increase after equivalent sucrose.¹ The ADA counting guidance (exclude erythritol entirely) reflects this evidence.

Erythritol’s prevalence in well-formulated keto and diabetes-appropriate products has increased significantly over the past decade. Monkfruit sweetener products almost universally use erythritol as the bulking agent (monk fruit extract is intensely sweet but in insufficient quantity to provide volume). Many high-quality stevia products use the same erythritol base. Brands that use erythritol as the primary sweetener (rather than maltitol) in chocolate and confections typically produce products with genuinely low glycemic impact — and the net carbs figure on those labels is meaningful.

Erythritol has one known adverse effect at high doses: some people experience a laxative effect at intakes above 50 g in a single sitting, though this threshold is substantially higher than the laxative threshold for other polyols. Mild gastric discomfort has been reported at 36 g in some subjects. At realistic dietary quantities (10–20 g per serving), erythritol is well-tolerated by most people.

A 2023 observational study in Nature Medicine raised concerns about elevated erythritol plasma levels and cardiovascular risk.⁵ It is important to note that this study measured endogenous erythritol (produced by the body’s pentose phosphate pathway, not from food) and the finding remains preliminary. Regulatory agencies including the FDA and EFSA maintain GRAS status for erythritol as a food additive. People with cardiovascular concerns should discuss this ongoing research with their physician, but it does not currently change ADA carb-counting guidance.

Digestive effects — the GI distress variable in carb counting

All sugar alcohols except erythritol are incompletely absorbed in the small intestine. The unabsorbed fraction passes into the large intestine, where it is fermented by gut bacteria — producing gas, bloating, and osmotic diarrhoea in proportion to the dose and the individual’s microbiome composition.

Tolerance thresholds (approximate, individual variation is substantial): xylitol: GI symptoms begin at approximately 20–30 g in a single dose; diarrhoea is more likely above 40 g. Sorbitol: symptoms at 10–20 g; significant diarrhoea above 25 g. Maltitol: symptoms at 30–40 g. Isomalt: relatively well-tolerated up to 30 g. Lactitol: GI symptoms at 20 g.

The “may cause digestive discomfort” labelling on sugar-free products is legally required when a food contains more than 10 g of polyol per serving in the EU (and recommended practice in the US). Products rarely display the specific threshold — the label is generic across all polyol-containing items.

The relevance for diabetes management: GI distress from sugar alcohols can affect glucose management through two mechanisms. First, accelerated transit reduces carbohydrate absorption from other foods consumed at the same meal, potentially lowering post-meal glucose below the bolus estimate. Second, diarrhoea produces dehydration and electrolyte shifts that can independently affect glucose readings. Patients experiencing recurrent unexplained post-meal hypoglycemia after “sugar-free” foods should consider polyol-induced transit effects as a contributing factor.

Practical sugar alcohol counting — a reference card for label reading

The counting rules, consolidated:

• Erythritol: count 0 g per g consumed
• Xylitol, sorbitol, lactitol, isomalt: count 0.5 g (half) per g consumed
• Maltitol: count 0.5–0.67 g per g consumed; use 0.67 for portions ≥20 g
• Glycerol (glycerin): count as full carbohydrate, 4 kcal/g
• Dietary fibre: count 0 (not digested to glucose)
• “Net carbs” on label: trust only if erythritol is the listed sugar alcohol; verify for all others. The fiber and net carb derivation guide explains how the fibre subtraction works alongside the sugar alcohol deduction.

Applied to five popular “diabetic-friendly” products:

1. Quest Bar (chocolate chip cookie dough, one bar): 22 g total carbs, 14 g fibre, 7 g sugar alcohols (erythritol). Correct count: 22 − 14 − 7 = 1 g base + 0 erythritol = ~1 g effective carbohydrate. Label net carbs: 1 g. Accurate.

2. Lily’s Dark Chocolate (40 g): 18 g total carbs, 5 g fibre, 12 g sugar alcohols (erythritol). Correct count: 1 g base + 0 erythritol = 1 g effective carbohydrate. Accurate.

3. Russell Stover Sugar Free Chocolate (one piece, ~12 g): 11 g total carbs, <1 g fibre, 9 g sugar alcohols (maltitol). Correct count: 2 g base + (9 × 0.67) = 2 + 6 = 8 g effective carbohydrate. Label net carbs: 2 g. Significant undercount.

4. Atkins Chocolate Peanut Butter Bar: 22 g total carbs, 8 g fibre, 10 g sugar alcohols (maltitol). Correct count: 4 g base + (10 × 0.67) = 4 + 6.7 = ~11 g effective carbohydrate. Label net carbs: 4 g.

5. Halo Top Ice Cream (½ cup): 16 g total carbs, 3 g fibre, 6 g sugar alcohols (erythritol). Correct count: 7 g base + 0 = 7 g effective carbohydrate. Label net carbs: 7 g. Accurate.

The pattern: erythritol-based products are generally label-accurate for diabetes counting; maltitol-based products require the manual two-thirds adjustment.

References

1. Bornet FR, Blayo A, Dauchy F, Slama G. “Gastrointestinal Response and Plasma and Urine Determinations in Human Subjects Given Erythritol.” Regulatory Toxicology and Pharmacology 24, no. 2 Pt 2 (1996): S296–S302.

2. American Diabetes Association. “Sugar Alcohols.” Diabetes Food Hub. Updated 2024. https://www.diabetesfoodhub.org/articles/what-are-sugar-alcohols.html

3. U.S. Food and Drug Administration. “Guidance for Industry: A Food Labeling Guide.” Section 6: Nutrition Labeling. Updated 2013. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-food-labeling-guide

4. Mooradian AD, Smith M, Tokuda M. “The Role of Artificial and Natural Sweeteners in Reducing the Consumption of Table Sugar: A Narrative Review.” Clinical Nutrition ESPEN 18 (2017): 1–8.

5. Witkowski M, Nemet I, Alamri H, et al. “The Artificial Sweetener Erythritol and Cardiovascular Event Risk.” Nature Medicine 29 (2023): 710–718.

6. Mäkinen KK. “Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol: Scientific Review and Instructions for Dentists and Other Health-Care Professionals.” International Journal of Dentistry 2016: 5967248.