Does interrupting insulin pumps impact glycemic control?

Nutrition Research Newsletter, March, 2008

Continuous subcutaneous insulin infusion (CSII) therapy allows for uninterrupted, around-the-clock delivery of insulin. In practice, patients disconnect their insulin pumps from their infusion sets when showering, changing clothes, swimming, exercising, or during intimate moments. Ranging in time from a few minutes to several hours, these periods of interrupted insulin infusion result in cessation of basal insulin delivery. Interrupting insulin delivery may be appropriate during periods of exercise when insulin sensitivity increases or during hyperglycemia, however, cessation of insulin delivery may be detrimental even for short periods, especially if it occurs when insulin resistance is at its peak.

A prospective, open label study was performed to measure the impact of short-term infusion-set disconnects and infusion-set changes on glucose levels. Enrolled in this study were 19 subjects with type 1 diabetes: 11 women and 8 men, with mean age 44 years (range 20-68), mean duration of diabetes 22.5 years (range 5-51), and mean A1C 7.3% (range 5.0 to 9.3%). All subjects used insulin pumps for at least 1 year.

Five subjects used insulin as part, 10 subjects used insulin lispro, and 4 subjects used insulin glulisine. Subjects wore continuous glucose monitoring system (CGMS) System Gold TM devices, which recorded glucose values every 5 minutes, throughout the study. The subjects were blinded to any CGMS glucose readings. In-clinic glucose measurements were performed. Alternate-site testing was not permitted. Per protocol, each subject work the CGMS system home after having it inserted by the research team. Subjects returned to the clinic at 7:00 a.m. in a fasting state, having taken no correction boluses of insulin, treatment for hypoglycemia, or food since midnight. Subjects disconnected from their infusion sets 1 hour after arriving at the clinic. They reconnected their CSII pumps to their infusion sets 30 minutes later. The subjects rested in a fasting state for an additional 3 hours after reconnecting. On a separate day, under similar conditions, subjects only changed their infusion sets. Glucose results were downloaded from the CGMS system at the end of each day.

Changing infusion sets did not affect short-term glucose control. However, the 30-minute interruption of basal insulin infusion resulted in significant glucose elevation; ~1 mg/dl for each minute basal insulin infusion was interrupted.

H. Zisser Quantifying the impact of a short-interval interruption of insulin-pump infusion sets on glycemic excursions. Diabetes Care; 31:238-239 (February, 2008). [Correspondence. Howard Zisser, MD, 2219 Bath St., Santa Barbara, CA 93105. E-mail: hzisser@sansum.org]