Objective: Continuous subcutaneous insulin infusion (CSII) is an effective method of intensive therapy for patients with type 1 diabetes; however, most studies have not examined long-term glycemic control. We evaluated the long-term efficacy of CSII in a cohort of adult patients with type 1 diabetes.
Subjects and methods: This was a retrospective observational study of 200 patients with type 1 diabetes who initiated CSII at a single outpatient clinic in Kingston, ON, Canada between January 1998 and December 2012. Data were collected from 3 months prior to and up to 15 years after initiation of CSII and included glycated hemoglobin (HbA1c) level and demographic factors potentially associated with glycemic control.
Results: Mean age and duration of diabetes at CSII initiation were 35.4 years and 22.4 years, respectively. Mean duration of CSII at the time of analysis was 6 years. Mean HbA1c at initiation of CSII was 8.7% and decreased to a nadir of 7.5% 6 months post-initiation (SD = 1.0) (P < 0.001). This increased over time (range, 7.8-8.2%) but remained lower than the pre-CSII HbA1c (P < 0.001). Shorter duration of diabetes prior to CSII initiation, history of missed appointments, mental illness, and active smoking were predictors of higher HbA1c on CSII. Pre-CSII HbA1c predicted long-term HbA1c on CSII.
Conclusions: The data demonstrate that in a clinic setting, patients on CSII maintain lower HbA1c values over a 1-10-year period compared with pre-CSII values. Poor pre-CSII HbA1c, history of missed appointments, mental illness, and active smoking are predictors of those less likely to achieve an HbA1c target of ≤ 7.0%.