Does continuous insulin infusion protect against diabetic eye disease?

This study looked at continuous subcutaneous insulin infusions (CSII) for the treatment of diabetic retinopathy (DR; eye disease). It found that compared to multiple daily injections of insulin (MDI), CSII resulted in a less worsening of DR.

Diabetic eye disease, also called diabetic retinopathy (DR), is a common complication of diabetes. It can progress to cause blindness. Patients with type 1 diabetes (T1D) are usually treated with multiple injections of insulin, usually around meal times and going to bed. This course of treatment is called multiple daily injections (MDI).  

Sometimes when diabetes is difficult to control, patients are treated with a device that releases insulin into their system throughout the day. This is called continuous subcutaneous insulin infusion (CSII). It can cause more stable insulin concentrations during the day and can better control blood glucose. A better diabetes control leads to a delay in complications such as DR. However, it is not clear if CSII reduces the risk of DR progression compared to MDI.

This study involved 415 patients with poorly controlled T1D. 204 patients were started on CSII. 211 patients stayed on MDI treatment. Patients were followed up for an average of 2.3 years. Their HbA1c (a measure of blood glucose control over the past 2-3 months) was monitored and they had regular eye exams to check for progression of DR.

Patients treated with CSII had a greater improvement in HbA1c than those treated with MDI. The CSII group had an average reduction in HbA1c of 0.4% compared to 0.2% in the MDI group.  

Patients treated with CSII had a lower risk of progression of DR. 18.6% of the CSII group showed progression of DR over 2.3 years, compared to 26.5% of the MDI group.

This study showed that patients with T1D on CSII treatment were less likely to have worsening of DR than patients on MDI.  

This study was based on medical records. More studies are needed to confirm these results.