Hyperhomocysteinemia and Increased Risk of Retinopathy

Increased total plasma homocysteine (tHcy) level—secondary to excessive alcohol intake, cigarette smoking, or deficiency of methylene-tetrahydrofolate reductase—is one new identified risk factor for atherosclerotic cardiovascular diseases and for macrovascular complications of diabetes (1,2). Homocysteine (Hcy)-induced vascular damage is probably initiated by reactive oxygen species formed during Hcy auto-oxidation in plasma and results in decreased nitric oxide production, platelet activation, impaired arterial vasodilatation, and isolated systolic hypertension (1). To assess whether hyperhomocysteinemia is also an independent risk factor for microvascular complications, we cross-sectionally studied the relations among tHcy levels, diabetic retinopathy (diagnosed by indirect ophtalmoscopy and retinal photography), insulin sensitivity and glomerular filtration rate (measured by euglycemic-hyperinsulinemic clamp and unlabeled iohexol …