Of 382 insulin-treated diabetic patients participating in a feasibility study of continuous subcutaneous insulin infusion (CSII) and alternative regimens in a large British clinic, 63 used CSII for a 2-yr period. Additionally 74 patients persisted with an intensified injection regimen and 85 continued on non-intensified therapy. There was no significant difference in mean glycosylated haemoglobin between the 3 groups at the study onset. At month 24 only the CSII group had significantly reduced mean glycosylated haemoglobin (11.0 +/- 1.8 (SD) at month 0; 9.8 +/- 1.9 month 24, p less than 0.001) although the intensified injection group experienced a significant reduction in mean glycosylated haemoglobin until month 18 (11.0 +/- 1.8 month 0; 10.1 +/- 1.4, p less than 0.001). Serious hypoglycaemia was not increased in the CSII-treated group compared with the intensified injection group. Thus it proved feasible to achieve sustained, improved glycaemic control in a large group of patients by the use of insulin pump therapy and the level of control was superior to that achieved by an intensified injection regimen.