Risk factors for diabetic macular oedema in type 2 diabetes: A case-control study in a United Kingdom primary care...

To identify risk factors associated with the development of DMO among patients diagnosed with type 2 diabetes managed in a primary care setting in the UK.

A case-control study nested in a cohort of incident Type 2 diabetes identified in The Health Improvement Network database from 2000-2007. Cases were people with DMO (N=211) and controls were a DMO-free sample (N=2194). No age restrictions were applied. Adjusted odds ratios and 95%CIs were estimated (OR; 95%CI).

DMO increased with high alcohol use (2.88; 1.49-5.55), cataracts (4.10; 2.73-6.15), HbA1c ≥7% (1.58; 1.08-2.32), systolic blood pressure ≥160mm Hg (2.03; 1.17-3.53), total cholesterol ≥5mmol/L (1.66; 1.15-2.39), LDL ≥3mmol/L (1.73; 1.14-2.61), and microalbuminuria (1.78; 1.16-2.73). Diuretic drugs were associated with a reduced risk of DMO (0.68; 0.47-0.99), as did smoking (0.47; 0.28-0.77), overweight (0.53; 0.30-0.96) or obesity (0.52; 0.30-0.91) at diabetes diagnosis, and high triglyceride levels (0.51; 0.35-0.74). Patients treated with anti-diabetic drugs showed higher risk of DMO than non-treated patients, particularly those with sulphonylureas (3.40; 2.42-4.78), insulin (3.21; 1.92-5.36) or glitazones (1.88; 1.17-3.04).

In patients with type 2 diabetes managed in primary care, multiple factors associated with DMO were identified, such as cataracts, microalbuminuria and high levels of HbA1c, systolic BP, total cholesterol, and LDL. Diuretic drugs were associated with a reduced risk of DMO. Treated diabetes, particularly with sulphonylureas, insulin or glitazones showed highest risk of DMO. The inverse association between smoking, obesity, and triglycerides and DMO deserves further research.