Continuous subcutaneous insulin infusions systems (CSII) are commonly used by patients with type 1 diabetes (T1D). A catheter (KT) allows transfer of insulin from the reservoir to the subcutaneous tissue. In clinical practice, KT are replaced every 2 or 3 days. This avoids skin irritation and other adverse events (AEs), including increases in mean blood glucose levels with longer usage. Historically, this commonly held assumption has been that the trade-off is worth it.
Pfützner et al recently reported a study on 22 adult T1D patients, all chronic users of CSII.1 The 6-month randomized crossover (2 x 3-month) study was conducted prospectively, in a real-world setting. Investigators assessed tolerability of 2-day and 4-day use. The number of KT-related AEs, treatment-related AEs, and other various AEs were significantly higher with 4-day use. With 2-day use, HbA1c improved (7.4 ± 1.2 vs 7.6 ± 1.2%, P < .05) and patient treatment satisfaction was higher. According to the authors, these data support the 2- to 3-day replacement recommendation; authors also expressed doubts on the economic benefits of longer KT wear.1
It seems to us that the Pfützner study data can be interpreted differently. In this type of study, AE frequency is the main issue. However, AE categories were poorly defined, and questionnaires used to record AEs were not validated. The alarming total number of AEs (n = 2664) in addition to hyperglycemia (n = 615) and hypoglycemia (n = 888) implies that CSII is an uneasy method, complicated on average by 1 AE daily. This unexpected deduction contradicts the overall treatment satisfaction reported by participants but is in line with a recent report pointing that AEs related to CSII and especially to KT usage are inappropriately assessed.2 Clarity of such studies would be increased if key numbers such as number of participants reporting AEs, KT used, KT changes, frequency of glycemia testing, real failure rate, and so on were reported in standardized fashion. Satisfaction scores (2.1 ± 0.6 vs 2.3 ± 0.6, P < .05) were lower with 4-day use. However, it is doubtful that this statistical difference translates into clinically measurable outcome. This is particularly so because scores were ranked on the positive side of the spectrum, that is, from 1 (very satisfied) to 6 (not at all satisfied). Finally, the cost-benefit of changing KT every 2 to 3 days or less frequently was not assessed and would require longer and larger trials.
Pfützner et al emphasize 2-day use. An important drawback of frequent KT replacement is the expense incurred by patients and health care systems. The 2 to 3-day replacement regimen however is not an evidence-based practice, with most reports in the scientific literature, including the Pfützner study, emanating from manufacturers themselves.3-5
Continuous glucose monitoring systems (CGMs) are transitioning from 7-day to 14-day wear. In our opinion, research should attempt to reduce the number of KT-related issues and extend the life of infusion sets in order to match CGMs life. Combining CGMs, algorithm, and insulin delivery system would reduce the number of required sites and be extremely convenient for awaited automated closed-loop insulin delivery.
Footnotes
Abbreviations: AE, adverse event; CGM, continuous glucose monitoring system; CSII, continuous subcutaneous insulin infusions; KT, catheter; T1D, type 1 diabetes.
Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
References
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