10 labile insulin-dependent diabetic patients treated with CSII were followed up for 6 to 16 months under conditions of everyday life. The mean blood glucose (MBG), glycosylated haemoglobin (HbA1), motor nerve conduction velocity (MCV), and respiratory heart arrhythmia at rest (RHA) were investigated. A significant improvement of metabolic control was observed (MBG 8.03 +/- 1.40 vs 5.18 +/- 0.87 mmol/l, p less than 0.01; HbA1 10.7 +/- 1.3 vs 8.7 +/- 1.6%, p less than 0.05) in comparison with the control values under intensified conventional therapy. MCV increased gradually but the average RHA remained unchanged. The psychological examination employing a questionnaire reflects that all patients selected were highly motivated and that their positive attitudes were further stabilized during pump treatment. An average of three mild hypoglycaemic episodes occurred per month per patient; these were no more than under intensified conventional treatment. Other minor clinical and technical complications occurred at a total frequency of one per month per patient and did not achieve therapeutical relevance.