This research study examines the effect of hyaluronidase on the length of time of insulin infusion set wear. The aim of the study is to improve the length of time that an infusion set can be worn by infusing hyaluronidase directly into the insulin infusion site.

The investigators would like to see if the use of hyaluronidase will improve insulin infusion set survival and improve the onset of insulin action. The investigators will also assess the accuracy of the Dexcom G4P sensors with extended site use beyond the 7 day FDA approved time frame.

The use of sensor information combined with the knowledge of infused insulin from pump therapy could potentially help us detect when an infusion set is beginning to fail. Information from the sensor function to the point of failure, and sensor function in response to Tylenol may allow us to develop special formulas to determine when a sensor is not working well. This will be very important for creating an artificial pancreas.

Thirty subjects will be enrolled. Fifteen patients from each of the two sites: Stanford University and University of Colorado.

Inclusion Criteria:

1. Clinical diagnosis of type 1 diabetes for at least one year and using an insulin pump for at least 3 months
2. Total daily insulin dose of at least 0.4 units/kg/day
3. The diagnosis of type 1 diabetes is based on the investigator's judgment; C peptide level and antibody determinations are not needed.
4. Age 12 to 45 years
5. Hemoglobin A1c level less than or equal to 10%
6. Willingness to infuse 1 ml of hyaluronidase (Hylenex) into the insulin infusion set after insertion on day 1 and day 3 of the week they are assigned to use hyaluronidase
7. Willingness to use a Silhouette or Comfort insulin infusion set throughout the study. The set includes the Duo Infusion Tubing for infusion of hyaluronidase (Hylenex).
8. Willingness to eat the same breakfast each morning for the first two weeks of the study
9. Willing to take two 500mg tablets of Tylenol Regular Strength and monitor glucose levels at ½, 1, 2, 4, 6, and 8 hours later.
10. For females, not currently known to be pregnant
11. An understanding of and willingness to follow the protocol and sign the informed consent
12. Must be able to understand spoken or written English

Exclusion Criteria:

1. Diabetic ketoacidosis in the past 6 months
2. Severe hypoglycemia resulting in seizure or loss of consciousness in the 6 months prior to enrollment
3. Known tape allergies
4. Current treatment for a seizure disorder
5. Cystic fibrosis
6. Active infection
7. A known medical condition that in the judgment of the investigator might interfere with the completion of the protocol such as the following examples:
8. Inpatient psychiatric treatment in the past 6 months for either the subject or the subject's primary care giver (i.e., parent or guardian)
9. Presence of a known adrenal disorder
10. If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, lack of stability on the medication for the past 2 months prior to enrollment in the study
11. Abuse of alcohol
12. Use of an OmniPod insulin infusion pump
13. Pregnant or lactating females

Subjects between 12-45 years (inclusive) with clinical diagnosis of type 1 diabetes for at least one year, using an insulin pump for at least 3 months, and with an A1C less than 10%. 30 total subjects across two sites were enrolled and randomized the first week to either be in the control or experimental arm.

Adverse events were recorded during subject's participation in the study (screening to final visit). Adverse events were followed from onset to resolution.

Adverse events were recorded during weeks of infusion set wear. In the study a total of 117 weeks of infusion set wear were available for analysis including 58 hyaluronidase weeks and 59 control weeks.

This was a proof on concept pilot study and included a small number of participants. There was no evidence that hyaluronidase prolonged infusion set wear.