Administration of insulin by continuous ambulatory peritoneal dialysis

Many patients with diabetic nephropathy undergoing continuous ambulatory peritoneal dialysis (CAPD) use their peritoneal access to administer insulin. Compared with the subcutaneous route, intraperitoneal (IP) insulin may display more consistent absorption, produce more physiologic insulin concentrations, and be more convenient to administer. However, there are no well-controlled trials that have demonstrated a clinically significant difference in glycemic control between IP and subcutaneous administration. For patients who choose to begin IP insulin at the time CAPD is initiated, the starting dose is 2-3 times the previous subcutaneous dose. For patients previously stabilized on CAPD, the conversion factor may be less. Doses are divided equally between bags. Some authors recommend adding more insulin to bags with a higher concentration of dextrose. In addition, the dose should be decreased when added to a bag used for an overnight dwell. Exchanges performed during the day may be timed to start 30 minutes before a meal. Unless clinical trials demonstrate a difference in efficacy between subcutaneous and peritoneal insulin administration, the route will remain a matter of patient preference.