This was a randomized double blinded study of a novel infusion set with and without heparin, hypothesizing that small doses of heparin would decrease thrombosis and subcutaneous inflammation. The MiniMed™ Quick-set™ infusion set was modified with a new tubing connector from current P-Cap. The P-Cap was modified to contain a foam (F) or a foam with heparin (F+H) connector. Visibly the sets appeared identical. Each participant wore two F and two F + H sets for 7 days or until set failure. The order of infusion set wear was randomly assigned. Infusion set failure was determined by unexplained hyperglycemia >250mg/dL with a failed correction dose, ketones >0.6mmol/L, evidence of infection, occlusion alarms, or adhesive failure. Infused set survival was compared to similar published 1-week studies using standard Quick-sets. There were 20 participants (mean age 29.5±8 years). Each set was worn 40 times. Length of wear and causes of failure are shown below. Length of wear was not different between the F and F+H groups, but both had improved length of wear compared to historical Quick-sets (p<0.05). There was no significant increase in insulin requirements or mean glucose values throughout the seven days of wear in any group. There was no difference in overall duration of wear between the F and F+H groups. Both infusion set groups intended for extended wear had significantly better survival than the historical Quick-Set™ group. Further studies are planned with the F group. Disclosure B.A. Buckingham: Advisory Panel; Self; ConvaTec Inc., Medtronic. Research Support; Self; Beta Bionics, Inc., Dexcom, Inc., Insulet Corporation, Medtronic, Tandem Diabetes Care. T. Marcal: None. L. Hoffman: None. G. Musolino: None. L. Ekhlaspour: None. G. Zhang: None. S. Chattaraj: Employee; Self; Medtronic. Funding Medtronic Diabetes