The present invention is directed to subcutaneous peritoneal injection catheters and methods which minimize catheter obstruction during use. The apparatus includes a receiving chamber or reservoir having a relatively small internal volume while employing a penetrable membrane and relatively enlarged target surface area. The reservoir is interconnected with the peritoneal cavity by a hollow stem. The penetrable membrane accommodates a hollow needle being inserted into the receiving reservoir and is configurated with a dome-like profile so that the membrane may also be depressed to expel insulin from the receiving reservoir into the peritoneal cavity in a direction generally toward the mesenteric peritoneal membrane.The distal end of the hollow stem (which is situated inside the peritoneal cavity), is constructed so as to minimize the likelihood of catheter obstruction during use by a patient. For example, in one presently preferred embodiment of the invention, the distal end of the stem is provided with two, parallel, diametrally enlarged flanges. The two flanges are unequal in size, and they are positioned on the stem such that the larger flange resides against the peritoneal membrane and the smaller flange is located immediately adjacent the distal opening of the stem. In addition, an antibacterial agent may be placed within the device, and the device may also be formed of or coated with a substance which inhibits body cell and bacterial growth.