peer reviewed ; Insulin detemir (Levemir) is a soluble human insulin analogue acylated with a 14-carbon fatty acid, which reversibly binds to albumin, thereby providing a more prolonged metabolic effect with lower variability as compared to NPH insulin taken as reference. Thanks to this pharmacokinetic and pharmacodynamic profile, insulin detemir is essentially used within a basal-bolus regimen. We report the results obtained in 232 type 1 diabetic patients recruited in Belgium in the frame of the international observational, open, prospective PREDICTIVE study. In patients initially treated with either NPH insulin or glargine, followed for 26 weeks, the shift to insulin detemir did not change HbA1c levels, but significantly reduced both the mean and the variability of fasting blood glucose levels while diminishing the risk of hypoglycaemic episodes, especially at night. Therefore, insulin detemir was associated with significantly improved quality of life. These changes were obtained with a slight increase in daily insulin doses but without weight gain.