Twelve C-peptide negative insulin-dependent diabetic patients participated in a randomized cross-over study of 6 months treatment with twice or thrice daily insulin injection therapy and continuous subcutaneous insulin infusion (CSII). Standard, non-intensified management conditions were maintained throughout. Glycosylated haemoglobin levels were similar on both regimens (9.2 +/- 0.5% versus 9.0 +/- 0.4%; CSII vs injection therapy; (mean +/- SEM). Capillary blood glucose concentrations before breakfast (5.2 +/- 0.4 mmol/l vs 9.1 +/- 0.8 mmol/l), after lunch (6.5 mmol/l +/- 0.8 vs 7.9 +/- 1.0 mmol/l) and before the evening meal (5.0 +/- 0.7 mmol/l vs 7.7 +/- 0.7 mmol/l) were lower on CSII, as were 24-hour urine glucose excretion and total insulin dose (39.3 +/- 2.2 vs 49.8 +/- 4.0 U/day). There was a significant positive correlation between fasting blood glucose values and glycosylated haemoglobin on injection but not pump treatment. Thus although blood glucose control at some individual daytime points appeared lower on CSII, overall diabetic control was similar on the two regimens.