Baseline haemoglobin A1c influences retinal function after long-term insulin pump therapy

Area of Science:

• Ophthalmology
• Endocrinology
• Diabetic Complications

Background:

• Type 1 diabetes mellitus (T1DM) management aims to prevent microvascular complications.
• Continuous subcutaneous insulin infusion (CSII) is a common T1DM treatment, but its long-term impact on retinal function requires further characterization.
• Electroretinography (ERG) and dark adaptometry are sensitive measures of retinal function.

Purpose of the Study:

• To assess the long-term effects of CSII on electroretinography (ERG) and dark adaptometry in T1DM patients.
• To investigate the influence of baseline glycemic control (HbA1c) on retinal function changes during CSII therapy.
• To correlate retinal function changes with metabolic control parameters over 3.5 years.

Main Methods:

• Prospective observational extension study following 13 T1DM patients from a primary 1-year CSII study.
• Retinal function assessed via full-field electroretinography (ERG) and dark adaptometry at 3.5 years post-CSII initiation.
• Optical coherence tomography and fundus photography were also performed.

Main Results:

• Mean ERG amplitudes decreased by 15-43% at 3.5 years compared to baseline (p<0.05).
• Dark adaptation rate returned to baseline after an initial transient acceleration at 1 year.
• Reduced ERG amplitudes correlated with higher baseline HbA1c (≥8.7%) and significant HbA1c reductions (>1.9%) after CSII initiation.

Conclusions:

• Subclinical retinal function deterioration occurs between 1 and 3.5 years of CSII, primarily linked to poorer pre-treatment glycemic control.
• Retinal function analysis provides valuable insights into diabetic complications, complementing structural assessments.
• Long-term CSII monitoring should consider retinal function, especially in patients with suboptimal baseline metabolic control.