Long-Term Effects of Continuous Subcutaneous Insulin Infusion on Glucose Control and Microvascular Complications in Patients With Type 1 Diabetes.

Background: We investigated the long-term effects of continuous subcutaneous insulin infusion (CSII) on glucose control and microvascular complications in patients with type 1 diabetes (T1D).

Methods: A total of 157 patients (59 M/98 W; age 39.1 ± 14.8 years) with T1D who switched from multiple daily injections to CSII and used CSII for at least one year were included. HbA1c levels and status of microvascular complications before and while under CSII were analyzed, retrospectively.

Results: The follow-up period was 4.0 ± 1.5 years. HbA1c significantly decreased from 8.4 ± 1.3 to 7.7 ± 1.3% (68 ± 14 to 61 ± 14 mmol/mol) after 1-year CSII and remained lower than pre-CSII levels during four years. Patients with pre-CSII HbA1c >8.0% (64 mmol/mol) showed significant improvement of HbA1c for four years, while those with pre-CSII HbA1c <8.0% showed no significant change. The prevalence of retinopathy, albuminuria, and chronic kidney disease (CKD) were respectively 39%, 12%, and 9% at CSII initiation. During follow-up, the incidence of retinopathy, albuminuria, and CKD were 3.6, 2.5 and 1.4/100 patient-years. Onset or progression of retinopathy occurred in 16 (27.1%) patients with diabetes duration >15 years, and in three (4.3%) patients with diabetes duration <15 years ( P < .01).

Conclusion: CSII was effective in improving HbA1c for up to four years, specifically in patients with HbA1c >8% (64 mmol/mol) prior to CSII. Incidence and progression rates of retinopathy and albuminuria were low, particularly in patients with a diabetes duration <15 years at CSII initiation. These results argue for not delaying a proposal of CSII initiation in T1D with sustained HbA1c >8% (64 mmol/mol).