Longitudinal Association of Glucose Metabolism with Retinopathy: Results from the Australian Diabetes Obesity and Lifestyle study (AusDiab)

Abstract

Objective: We determined the longitudinal association of glucose metabolism with retinopathy in a representative sample of the Australian population.

Research Design and Methods: The Australian Diabetes Obesity and Lifestyle study (AusDiab), is a national, longitudinal study of adults aged ≥25 years from 42 randomly selected areas of Australia. Retinopathy was assessed at baseline in 1999-2000 and 5-years later in 2004-2005 in participants identified as having diabetes (based on self report and oral glucose tolerance test), impaired glucose metabolism and in a random sample with normal glucose tolerance. Complete retinal data were available for 1192 participants. Photographs were graded at two time points according to a simplified version of the Wisconsin grading system.

Results: The five-year incidence of retinopathy was 13.9% and 3.0% among those with known and newly diagnosed diabetes mellitus at baseline, respectively. Of those who developed incident newly diagnosed diabetes (NDM) at follow-up, 11.9% had retinopathy at baseline as compared with 5.6% of those who did not progress to incident NDM (p=0.037). After adjustment for factors identified as risk factors for diabetes, persons with retinopathy signs at baseline were twice as likely to develop incident NDM compared to those who did not have retinopathy signs at baseline.

Conclusions: The 5-year incidence of retinopathy was 13.9% among persons with known diabetes. Non-diabetic persons with retinopathy signs at baseline had a two-fold higher risk of developing incident NDM 5 years later. This provides further evidence that mild retinopathy signs may be a pre-clinical marker of underlying microvascular disease and future diabetes risk.