Erythritol (20 g in solution) was administered orally in a single-dose to 5 patients with diabetes. Serum erythritol levels reached a peak 1 hr after administration and then declined rapidly. Total urinary excretion was 82.0 +/- 3.7% within 24 hr and 88.5 +/- 3.3% within 72 hr. Serum glucose and insulin levels remained unchanged until a meal was taken (3 hr after erythritol administration) and then increased. Free fatty acids and 3-hydroxybutyric acid levels increased after erythritol administration but dropped after ingestion of food. In a separate clinical trial, erythritol (20 g) was administered orally daily for 14 days to 11 patients with diabetes. Mean serum glucose and hemoglobin A1c levels decreased over the time period. Indices of renal function-blood urea nitrogen, creatinine, and beta 2-microglobulin-did not change significantly. The single dose study suggests that erythritol exerts no significant effects on the metabolism of diabetic patients. Two-week daily administration of erythritol had no adverse effect on blood glucose control.