The diet of diabetic patients should not contain sugars with insulin- dependent utilization and rapid absorption. For this reason, the diabetic patient is, in general, not allowed to take glucose, sucrose or maltose. Up to now, we used fructose or the polyol sorbitol as sugar substitutes. Both substances have an almost identical metabolic pathway, since sorbitol after dehydrogenation by sorbitol-dehydrogenase is converted to fructose and is now subject to the same metabolism as fructose. It is well known that this catabolic pathway is insulin-independent. Several groups could demonstrate that the breakdown of xylitol is also independent of insulin, for this metabolite appears in the glucuronic acid-xylose-cycle and enters the Horecker-shunt at the D-xylose 5-phosphate step. It was now of interest to find out whether this property which recommends xylitol as a sugar substitute for diabetic subjects adds to the advantage of a relatively slow absorption of the polyol. We decided, therefore, to examine the absorption of xylitol in man and rat and compare the results with those obtained with other kinds of sugars and polyols.