Glycemic Control After T1D Onset Associated with Long-Term Diabetic Retinopathy Risk

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Patients with diabetic retinopathy showed significantly higher updated first-year HbA1c and at follow-up compared to those free from DR.

New data show glycemic control obtained during the first year after type 1 diabetes (T1D) onset is associated with long-term risk of diabetic retinopathy independent of subsequent glycemic control.

Investigators suggest that the pathological pathway due to hyperglycemia and leading to DR may start years before the onset of the complication, thus strict monitoring of blood glucose values following diabetes onset may help early stratification of long-term risk.

“The results confirm and expand the previous literature, showing long-term effects of previous periods of dysglycemia on the risk of chronic complications,” wrote study author Ernesto Maddaloni, MD, PhD, Sapienza University.

The study was presented at the American Diabetes Association (ADA) 2022 Scientific Sessions.

Maddaloni and colleagues set out to understand if the long-term risk of developing chronic complications in T1D is influenced by clinical features at the onset of the disease and by the glycemic control obtained within the first year after diagnosis.

They retrospectively studied a cohort of patients, enrolled ≤1 year of diagnosis in intervention trials run by the Immunotherapy Diabetes (IMDIAB) study group and followed up to 33 years. The IMDIAB group is a multicenter network consisting of clinicians and scientists working on immunology of T1D in 6 major diabetes clinics in Rome, conducting 10 randomized clinical trials (RCT) between 1988 and 2006 with people newly diagnosed with T1D.

Investigators collected baseline features at onset and first year of the disease during the study, including age at diagnosis, length of symptoms before diagnosis, HbA1c, fasting C-peptide, insulin requirement, and blood glucose concentrations at diagnosis and then 3, 6, 9, and 12 months after onset of the disease.

The participants in the study were reached by phone and then follow-up data from 150 IMDIAB participants (56.3% males, age at diagnosis: 12 years) was obtained between January 2020 - January 2021 through the consultation of medical records. It included demographic information, anthropometrics, vitals, ongoing insulin therapy, and presence of diabetic complications.

From the time of the last follow-up, the population was aged 38 years, the median disease duration was 25 years, and the HbA1c was 7.3%. Data show DR was diagnosed in 26 (17.3%) patients.

Investigators noted patients with DR showed similar HbA1c at onset, but higher updated first-year HbA1c (6.8% vs 6.3%, P = .037) and higher HbA1c at follow-up (8.0% vs 7.2%, P = .005) compared to those free from DR.

Moreover, a higher updated first-year HbA1c was also a significant predictor of higher HbA1c at follow-up (​​β, 0.24, P = .015). In the multivariate model, the association between the updated first-year HbA1c and DR did not lead to significant changes after adding HbA1c at follow-up and disease duration, according to investigators.

“The significant but weak correlation between the mean glycemic control obtained during the first year and the HbA1c values measured at follow-up, also strongly associated with diabetic retinopathy, might suggest that people who struggle controlling their blood glucose concentrations soon after T1D diagnosis may have difficulties to achieve good HbA1c values later-on,” Maddaloni concluded.

The study, “Glycated Hemoglobin In The First Year After Diagnosis of Type 1 Diabetes Is An Important Risk Factor For Diabetic Retinopathy: THE IMDIAB 25 Years Follow-Up Study,” was presented at ADA 2022.