Context: Asymmetric dimethylarginine (ADMA) has recently emerged as an independent risk marker for cardiovascular disease but studies investigating the ADMA levels in type 1 diabetes mellitus (DM) are scarce.

Objective: We aimed to evaluate plasma ADMA, L-arginine concentrations and L-arginine/ADMA ratio in uncomplicated type 1 diabetic patients and controls.

Design and Subjects: Forty patients with type 1 DM who did not have clinical evidence of vascular complications and 35 healthy controls were included in the study.

Results: Plasma ADMA concentrations were higher (2.6 ± 1.9 vs 1.7 ± 0.7 µmol/L, P < 0.01) and L-arginine levels were lower (79.3 ± 22.6 vs 89.6 ± 19.4 µmol/L, P < 0.05) in the diabetic group compared to controls. L-arginine/ADMA ratio were also lower in the diabetic group (38.7 ± 17.1 vs 62.0 ± 27.9, P < 0.0001). In diabetic patients, logADMA correlated positively with body mass index (BMI) (P = 0.01), fasting blood glucose (FBG) (P = 0.006), low-density lipoprotein cholesterol (LDL-c) (P = 0.01) and negatively with high-density lipoprotein cholesterol (HDL-c) (P = 0.03). L-arginine/ADMA ratio correlated negatively with BMI (P = 0.004), FBG (P = 0.02), LDL-c (P = 0.01) and positively with HDL-c (P = 0.04). In controls, logADMA and L-arginine/ADMA ratio correlated with BMI and LDL-c (P < 0.05). In regression analysis, BMI predicted 15% variance of ADMA levels (P = 0.02).

Conclusions: We demonstrated that ADMA increases and L-arginine/ADMA ratio decreases even before the development of vascular complications in type 1 DM.