Risk factors for diabetic retinopathy in the Cree of James Bay

BACKGROUND: The purpose of this project was to evaluate risk factors for diabetic retinopathy in the Cree population of James Bay, Ontario. METHODS: A retrospective cohort design was employed. The cohort was made up of all known individuals who had previously been diagnosed with diabetes in the communities of Moose Factory and Moosonee, Ontario. Hypertension, body-mass index, serum lipid levels, renal function status, and hemoglobin AIC were the main exposures of interest. Values for these variables were determined from a retrospective chart review and were sought for each individual for a five-year interval beginning one year following the diagnosis of diabetes. Relative risks for the association of these variables with diabetic retinopathy were determined through both univariate and multivariate Poisson regression. The main outcome of interest in this study was the presence or absence of any diabetic retinopathy in either eye, as determined by a retinal specialist. RESULTS: Significant univariate risks for the development of retinopathy included duration of diabetes, body-mass index, hemoglobin AIC, fasting blood glucose, insulin treatment, and serum cholesterol levels. In multivariate analyses, predictors of diabetic retinopathy included body-mass index, insulin treatment, and serum cholesterol levels. An increase in body-mass index reduced the risk of diabetic retinopathy (Relative Risk [RR] 0.64 per five kg/m², 95% Confidence Interval [CI] 0.04 to 1.00). Insulin therapy was associated with an increased risk of retinopathy when compared to individuals on dietary therapy alone (Relative Risk [RR] 4.71, 95% Confidence Interval [CI] 1.16 to 19.16). For individuals with serum cholesterol levels above the average for the cohort, 5.2mmol/L, the risk of retinopathy was increased (Relative Risk [RR] 2.38, 95% Confidence Interval [CI] 0.98 to 5.79). INTERPRETATION: Elevated serum cholesterol, lower body-mass index and insulin treatment were all associated with an increased risk of diabetic retinopathy in the Cree of James Bay, Ontario.