As diabetic retinopathy (DR) can occur even in well-controlled patients with type 2 diabetes (T2D), our study sought to determine whether it might be related to ‘glucose memory’ by evaluating patients’ HbA1c over previous years and their skin autofluorescence (SAF).

In 334 patients with T2D and HbA1c levels≤8%, their available values of HbA1c from previous years were collected, and their SAF measured by an advanced glycation end-product (AGE) reader. Binary logistic regression analysis was then used to correlate DR with previously recorded HbA1c levels and to SAF, with adjustment for DR risk factors [age, gender, BMI, duration of diabetes, arterial hypertension, diabetic kidney disease (DKD), blood lipid levels and statin treatment].

Our patients were mostly men (58.4%) aged 63±10years, with a duration of diabetes of 13±10years and HbA1c=7.1±0.7%. Of these patients, 84 (25.1%) had DR, which was associated with longer duration of diabetes and greater prevalence of DKD. A total of 605 HbA1c values from previous years were collected for time periods −4±3 months (n=255), −16±4months (n=152), −30±4months (n=93) and −62±26 months (n=105). After adjustment, the association between DR and having an HbA1c higher than the median was significant only for the oldest previous HbA1c values: OR=6.75, 95% CI: 1.90–23.90. Moreover, SAF values were higher in those with DR [2.95±0.67 arbitrary units (AU)] vs 2.65±0.65 AU with no DR (P<0.01) and were also associated with the oldest previous HbA1c values (P<0.01).

Our study found that 25.1% of our well-controlled T2D patients had DR, which was related to both their HbA1c levels from 5years prior to study admission and their SAF values, a marker of glucose memory.