medwireNews: People with type 1 diabetes using an insulin pump might have a reduced risk for diabetic retinopathy progression compared with those on multiple daily injections (MDI), suggest results from a Scottish observational study.
Shareen Forbes (Edinburgh Centre for Endocrinology and Diabetes, UK) and fellow authors used the Scottish Care Information – Diabetes database to obtain data from 415 adults with type 1 diabetes who completed a structured diabetes education course, of whom 204 individuals started using an insulin pump between 2013 and 2016. In all, 18.6% of pump users had diabetic retinopathy progression after an average 2.3 years of follow-up compared with 26.5% of the 211 individuals who continued on MDI during the same period.
After adjusting for factors such as age, sex, diabetes duration, and baseline glycated hemoglobin (HbA1c), the researchers found that pump users had a reduced risk for diabetic retinopathy progression compared with those using MDI, at a hazard ratio of 0.56.
The team notes that at baseline, insulin pump users had a lower median age (38 vs 43 years), age of diabetes diagnosis (15 vs 21 years), and HbA1c (66 vs 67 mmol/mol [8.2 vs 8.3%]), as well as higher diastolic blood pressure (78 vs 77 mmHg), than those using MDI. Most individuals in both groups had either no diabetic retinopathy (grade R0, 46–47%) or mild (grade R1, 48–53%) diabetic retinopathy.
These results provide “reassurance that, in adults with no or mild diabetic retinopathy risk at baseline, there is no evidence of early diabetic retinopathy worsening, with diabetic retinopathy risk reduction following the introduction of [insulin pump] therapy,” write Forbes et al in Diabetologia.
At the 1-year follow-up, people using insulin pumps had a significantly greater HbA1c reduction from baseline compared with those receiving MDI therapy (6 mmol/mol [0.6%] vs 1 mmol/mol [0.1%]), and higher baseline HbA1c was significantly associated with greater reductions in HbA1c at 1 year.
In the MDI group, having a baseline HbA1c higher than 75 mmol/mol (9.0%) versus lower than 58 mmol/mol (7.5%) was associated with a significantly higher proportion of people with diabetic retinopathy progression, at 40.6% versus 13.6%. This association was not observed in the insulin pump group, however, leading the researchers to speculate that “[glycemic] factors intrinsic to [insulin pump] therapy are protective against diabetic retinopathy progression in those with high baseline HbA1c.”
They say that “[c]hange in HbA1c at follow-up, irrespective of baseline glycaemic status, did not significantly affect diabetic retinopathy progression in either group.”
The team concludes that their findings “will help facilitate patient-centred decision making regarding insulin treatment options and retinopathy screening intervals following treatment changes.”
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