Baseline (2007) demographic, clinical and biochemical measurements and retinopathy grading for 281 subjects included in the 2007 study categorised by follow-up: Traced and assessed in 2012 (n = 135) or not seen in 2012 (n = 146).

Subjects not seen in 2012 further classified into those confirmed dead (n = 15) and those lost to follow-up (n = 131). Statistical comparison (analysis of bias): subjects seen in 2012 (n = 135) vs subjects not seen in 2012 (n = 146).