Six year incidence and progression of diabetic retinopathy: results from the Mauritius diabetes complication study

AIMS: To determine the incidence, progression and risk factors for diabetic retinopathy in the multiethnic population of Mauritius.

METHOD: A longitudinal, population-based study was conducted in Mauritius, during 1987, 1992 and 1998. Participants identified through the study as having diabetes (both known and newly diagnosed, by self-report and oral glucose tolerance test) and one in four participants with impaired glucose tolerance (IGT) underwent complications screening in 1992 and 1998. Retinal photographs were taken using a TRC-50VT retinal camera in three fields of the right eye (centred on the optic disc; macula (temporal to the optic disc); and nasal to disc). Photographs were graded according to a simplified version of the Wisconsin grading system.

RESULTS: The 6-year incidence of diabetic retinopathy was 23.8% (sight-threatening in 0.4%). Among those with known diabetes mellitus (KDM) and free of retinopathy at baseline the incidence of non-proliferative diabetic retinopathy (NPDR) was 29.2% and proliferative diabetic retinopathy (PDR) was 1.0%. Among those with newly diagnosed diabetes mellitus (NDM) at baseline the incidence of NPDR was 19.1% (no incident cases of PDR were found). Independent risk factors for retinopathy using the baseline population characteristics were duration of diabetes and fasting plasma glucose.

CONCLUSIONS: This is one of the few recent population-based studies of diabetic retinopathy undertaken in a developing nation. The incidence of retinopathy in Mauritius was high among those with NDM at baseline, with one in five developing retinopathy over 6 years. These results support the concept that screening for diabetes is important.