The long-term acceptability and feasibility of continuous peritoneal insulin infusion (CPII) from external pumps was evaluated in 40 insulin-dependent diabetic patients continuously treated for 1-27 months (mean 12 months). Blood glucose control was satisfactory and did not deteriorate with time (glycosylated haemoglobin 8.1 +/- 1.1%, mean +/- S.D., normal range 5.5-7.5%). Major problems included 1 episode of local peritonitis, 12 hypoglycaemic comas, 7 severe hyperglycaemic episodes, all cured without sequelae. Minor problems were frequent, mostly pump and catheter-related. Pump and catheter survival rates were 46% and 70% at one year, respectively. No peritoneal reaction was noted apart from occasional tissue growth around the catheter. This method of insulin treatment was judged satisfactory and acceptable by most of the subjects. Only one patient dropped out, after 1.5 years. These results were achieved through stringent selection of patients, intensive education with strict instructions, careful medical care, and possibly through the inherent physiological advantages of intraperitoneal insulin infusion.