BACKGROUND: Diabetic macular edema (DME) is a sightthreatening microangiopathy that can appear at early stages of retinopathy and is common in type II diabetic patients.
OBJECTIVES: To estimate the DME incidence rate (IR) and to identify risk factors for incident DME in type II diabetes in the context of current management of diabetes in UK primary care.
METHODS: We conducted a Case–Control analysis nested in a cohort of newly diagnosed type II diabetic patients aged 1–84 years identified in The Health Improvement Network (THIN) database between 2000 and 2007. We followed patients until diagnosis of DME (N = 211), 85 years of age, death, or 31st December 2008. DME diagnosis was confirmed by general practitioners in 86% of instances. Cases were all patients diagnosed with DME and controls were a random sample of study cohort members (N = 2,194). No matching was applied. Index date was the DME date for cases and a random date for controls. Adjusted odds ratios (OR;95% CI) were estimated for life-style factors, medical condition and hypoglycemic drugs.
RESULTS: The IR of DME was 0.84 per 1,000 person-years (95% CI: 0.73–0.96). DME risk (OR; 95% CI) increased with glycated hemoglobin > or = 7% (1.49;1.07–2.09), systolic BP > or = 160 mmHg (2.22;1.31–3.76), proteinuria (1.94;1.37– 2.74), LDL > or = 3.0 mmol/L (1.75;1.16–2.64), total cholesterol > = 5 mmol/L (1.65; 1.15–2.37), and cataracts (4.03;2.69–6.03). DME risk was decreased among current (0.48;0.29–0.79) and former smokers (0.54;0.35–0.85), overweight (0.58;0.32–1.04) and obesity (0.57;0.33–0.98), and subjects with triglycerides/L > or = 1.7 mmol (0.55;0.38– 0.79). Diabetes duration, diastolic BP or HDL were not associated with DME. Use of sulphonylureas (2.97;2.10– 4.20), insulin (2.82;1.67–4.75) and glitazones (1.82;1.13– 2.93) were associated with an increased risk of DME.
CONCLUSIONS: We identified multiple factors associated with DME such as high glycated hemoglobin, systolic BP, total cholesterol, LDL, proteinuria, cataracts, and use of hypoglycemic drugs. The inverse association between smoking, obesity and triglycerides with risk of DME deserves further research.
