Twenty-one patients with insulin-dependent diabetes mellitus (IDDM) participated in a 20-week randomized cross-over comparison of continuous subcutaneous insulin infusion (CSII) with intensified conventional treatment (ICT) using the NovoPen. The Medix or the Auto-Syringe pumps were used for CSII and, during ICT with NovoPen, conventional plastic syringes were used for injections of intermediate-acting insulin at bedtime. At entry HbA1c, was 8.7 +/- 0.4% (mean +/- SE) in CSII patients and 8.8 +/- 0.5% in the ICF group. HbA1c declined significantly in both groups (ICT 7.6 +/- 0.2%; CSII 7.6 +/- 0.2%) though there was no significant difference between the responses. Overall mean blood glucose was slightly but significantly lower during CSII than during ICT (CSII: 7.6 +/- 0.2 mmol/l; ICT: 8.7 +/- 0.4 mmol/l, p less than 0.05). The number of hypoglycaemic episodes did not differ significantly between patients treated with NovoPen and CSII. At the end of the study, a questionnaire revealed that all but one patient preferred ICT with NovoPen to conventional therapy. Given the choice for future treatment, 6 patients chose CSII, 12 patients preferred ICT with NovoPen and 1 was unsure.