Homocysteine levels during fasting and after methionine loading in adolescents with diabetic retinopathy and nephropathy

Abstract

Objective: To assess plasma homocysteine levels in adolescents and young adults with type 1 (insulin-dependent) diabetes with and without microvascular complications. Study design: Homocysteine levels were measured during fasting and after methionine loading in plasma of 61 patients with onset of diabetes before the age of 12 years and duration of disease longer than 7 years. They had an albumin excretion rate (AER) between 20 and 200 μg/min in 2 of 3 overnight urine collections in a period of 6 months and/or retinopathy. Patients with persistent microalbuminuria were divided into 2 groups: subjects with AER of 20 to 70 μg/min and patients with AER of 70 to 200 μg/min. Adolescents (n = 54) without signs of diabetic retinopathy or nephropathy and matched control subjects (n = 63) were also studied. Results: Homocysteine concentrations before and after methionine load were higher in adolescents with diabetic complications than in healthy subjects (fasting values: 12.4 ± 7.9 μmol/L vs 7.8 ± 4.2 μmol/L; P <.01; after methionine load: 28.1 ± 13.2 μmol/L vs 16.6 ± 7.3 μmol/L; P <.005). Values of 11.9 μmol/L or higher were considered to constitute fasting hyperhomocysteinemia. The increase of homocysteine concentrations was particularly evident in young diabetic patients with AER >70 μg/min (fasting values: 14.7 ± 5.6 μmol/L; after methionine load: 34.2 ± 12.6 μmol/L) and in patients with proliferative retinopathy (fasting values: 15.1 ± 5.0 μmol/L; after methionine load: 36.8 ± 12.5 μmol/L). Conclusions: Increased plasma homocysteine concentrations may contribute to increased morbidity and death from cardiovascular disease in adolescents and young adults with diabetic retinopathy and nephropathy. (J Pediatr 2000;137:386-92)