Sugar substitutes at a glance: which raises blood sugar, and which doesn’t?

Erythritol: the blood-sugar-neutral favourite

Erythritol practically doesn’t raise blood sugar (glycaemic index around 0) and is calorie-free. It’s largely excreted unchanged and is therefore usually well tolerated, though in larger amounts it affects digestion slightly in some people. For the blood-sugar-conscious it’s thus the most straightforward candidate.

Xylitol (birch sugar): tooth-friendly, with a small blood-sugar effect

Xylitol, often sold as birch sugar (it’s the same substance), raises blood sugar only a little (GI ~7–13, largely insulin-independent). Its plus point: it’s considered good for the teeth, because caries bacteria can’t metabolise it into acid. The downside: from about 20–30 g per day it can be laxative and cause bloating.

Maltitol: the problem case among sugar alcohols

Maltitol is the exception: it raises blood sugar noticeably (GI 35, about half as high as table sugar) and can also be laxative. It’s often found in “sugar-free” chocolate. Anyone watching their blood sugar should read the ingredients list especially carefully for maltitol. Why that is, and how “sugar-free” can mislead, is covered in detail in the article on “sugar-free” sweets.

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