Limitations of intensive diabetes treatment with subcutaneous insulin include achievement of only near-normoglycaemia and increased risk of hypoglycaemia. Programmable implantable pumps permit variable rates of intraperitoneal insulin infusion. The French experience represents 224 type I adult diabetic patients followed up for 353 patient-years in seven centres. Compared with pre-implantation values with intensive subcutaneous insulin, glycaemic control was significantly improved with implantable pumps: glycosylated haemoglobin fell from 7.4 (1.8)% to 6.8 (1.0)% at 6 months (mean, SD, p < 0.001). The incidence of severe episodes of hypoglycaemia decreased from 15.2 to 2.5 per 100 patient-years (p < 0.001). Intraperitoneal insulin delivery with implantable pumps improved the risk-benefit ratio of intensive insulin.