Influence of local skin temperature and choice of insulin analog on catheter occlusion rates during continuous insulin infusion: an exploratory study.

AIMS

The aim of this study was to determine whether changes in local skin temperature over which the infusion catheters pass when using insulin pump therapy and the choice of rapid-acting insulin analog influence the risk of catheter occlusion.

SUBJECTS AND METHODS

Twenty healthy volunteers were assigned to wear insulin pumps primed with insulin glulisine and insulin aspart in a randomized order each for a duration of 5 days and a temperature probe (taped to the skin near the insulin catheter). To reproduce the effect of subcutaneous infusion, the insulin catheter was inserted into an absorbent sponge in a plastic bag strapped to the subject's abdomen. Basal infusion rates were programmed at 0.2 IU/h, and 2-IU boluses were given three times a day with meals.

RESULTS

Average skin temperature ranged between 33.5°C and 36.68°C for insulin glulisine and 32.35°C and 35.28°C for insulin aspart, with no difference in skin temperature between treatments or between the first and second week of the study. Nine occlusions were seen in eight subjects with an overall rate of occlusion of 22.5% (95% confidence interval, 21.9-61.3%) and were more likely to occur in the second week. On an individual level the risk of occlusion was similar for insulin glulisine and insulin aspart (odds ratio, 0.87%; P=0.6).

CONCLUSIONS

Overall, in this small study simulating subcutaneous insulin infusion, the rate of catheter occlusion was low and unaffected by local fluctuations in ambient skin temperature. There was no significant difference between the two rapid-acting insulin analogs tested. Where occlusions occurred, they were more likely to happen beyond the manufacturer's recommended 72-h limit for catheter use.