Sugar Alcohols and Blood Glucose: Erythritol, Xylitol, Maltitol

Sugar alcohols have become common replacements for sugar in low-carb products. On a ketogenic diet, understanding how erythritol, xylitol and maltitol affect blood glucose helps maintain nutritional ketosis. These compounds occur naturally in some fruits and vegetables, but most commercial versions are manufactured.

How sugar alcohols work

Chemically, sugar alcohols are neither sugars nor alcohols. Their structure allows them to activate sweet taste receptors while being partially resistant to digestion. A 2013 study in the British Journal of Nutrition found very-low-carbohydrate diets including sugar alcohols produced better glycaemic control than low-fat diets (Bueno et al., 2013). the keto adaptation timeline explains why this matters.

Erythritol: the keto favourite

Erythritol has virtually no effect on blood glucose or insulin levels. About 90% gets absorbed in the small intestine and excreted unchanged in urine. The remaining 10% reaches the colon where gut bacteria ferment it minimally. You’ll find erythritol in Tesco’s own-brand stevia sweetener (£2.50 for 200g) and most keto baking products.

Xylitol: moderate impact

Xylitol has about 40% of sugar’s calories and causes a modest rise in blood glucose. It’s commonly used in chewing gum and dental products. Diabetics should account for about half xylitol’s carbs in their daily total. A 2005 study in Nutrition & Metabolism showed low-carb diets with xylitol still improved HbA1c more than low-glycaemic diets (Yancy et al., 2005).

Maltitol: the problematic one

Maltitol spikes blood glucose nearly as much as regular sugar. It’s found in many ‘diabetic’ chocolates and ice creams. About half gets absorbed as glucose, while the rest ferments in the colon, often causing digestive upset. Sainsbury’s sells maltitol-sweetened chocolate bars for £3.50 that claim to be sugar-free but contain 45g carbs per 100g.

What this means in practice

UK supermarkets increasingly stock keto-friendly options. Waitrose’s No.1 erythritol blend (£4 for 250g) works well in baking. For those managing diabetes or insulin resistance, common keto electrolyte mistakes can compound blood sugar issues. Always check labels – ‘no added sugar’ doesn’t mean carb-free.

Frequently asked questions

Do sugar alcohols count towards net carbs?

Most people subtract erythritol entirely. Subtract half of xylitol’s carbs. Count all maltitol carbs. This aligns with how they actually affect blood glucose.

Why does maltitol raise blood sugar so much?

Maltitol gets broken down into glucose during digestion. Its chemical structure resembles maltose, which enzymes easily convert to glucose.

Can sugar alcohols kick you out of ketosis?

Erythritol won’t. Xylitol might in large amounts. Maltitol frequently does. Individual responses vary based on insulin sensitivity.

The bottom line

Sugar alcohols vary widely in their blood glucose impact. Erythritol is safest for ketosis, while maltitol behaves much like sugar. Checking labels helps avoid products that undermine low-carb efforts. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store.

Educational only — not medical advice. This article is for general information. Speak to your GP before changing your diet, especially if you have type 1 or type 2 diabetes, kidney or liver disease, are pregnant or breastfeeding, or take medication for blood pressure, cholesterol, or blood glucose.

References

Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition. https://doi.org/10.1017/S0007114513000548
Yancy WS, Foy M, Chalecki AM, Vernon MC, Westman EC (2005). A low-carbohydrate, ketogenic diet to treat type 2 diabetes. Nutrition & Metabolism. https://doi.org/10.1186/1743-7075-2-34