Malfunctions occurred in 239 (68%) pumps. The incidence rate was 33/100 pump-years. There were 28 (12%) complete failures, 17 (7%) alarms, 83 (35%) mechanical defects, and 105 (44%) minor defects. Survival curves did not differ according to pump brand and model. Hyperglycemia occurred in 2.9% of cases. In multivariate analysis, only patient age less than 40 years at the initiation of pump therapy was associated with higher risk of malfunction (hazard ratio 1.64; 95% confidence interval 1.19-2.24; P = 0.002)