Long-term therapy of IDDM with an implantable insulin pump. The Implantable Insulin Pump Trial Study Group

To examine the long-term benefits and risks of treatment of IDDM with an implantable programmable insulin pump.

Seventy-six patients with IDDM were studied at nine clinical centers. After 3-4 months of intensive subcutaneous therapy, the Infusaid Model 1000 pump was implanted, and insulin was delivered either intraperitoneally or intravenously for an average of 39.6 +/- 10 months (251 patient-years). Data was collected for glycemic control, lipid levels, weight gain, insulin requirements, adverse events, and quality of life. Sixty-three patients were also followed for 8.5 +/- 6.3 months (45 patient-years) after pump therapy was discontinued.

Mean quarterly HbA1c fell with subcutaneous intensive therapy and remained stable on implantable pump therapy between 6.9 and 7.5%. Severe hypoglycemia was relatively rare, with only 4 episodes/100 patient-years of implantable pump therapy. This rate was significantly less than with subcutaneous intensive therapy before implantable pump initiation (33 episodes/100 patient-years) or after discontinuation of implantable pump therapy (36/100 patient-years) (P < 0.003). Weight did not increase significantly in the 1st year of therapy, but increased by 2.0 +/- 4.3 kg after 3 years of therapy. There were no significant differences in metabolic control or adverse events between intraperitoneal and intravenous insulin therapy except for minor differences in lipid levels and the more frequent development of catheter obstruction with intravenous delivery. Most pump slow-downs and catheter occlusions were corrected noninvasively. Quality of life, as measured by the Diabetes Control and Complications Trial instrument, showed high satisfaction and improved impact scores.

Long-term implantable pump therapy maintained HbA1c in a range similar to intensive subcutaneous therapy, but with fewer episodes of severe hypoglycemia. Although pump and catheter occlusions remain a limitation, patient satisfaction with implantable pump therapy remains high.