Deficiency of microsomal glucose-6-phosphatase in liver and kidney leads to glycogen storage disease type 1a (GSD 1a). Notwithstanding intensive dietary therapy, moderate to severe dyslipidaemia and microalbuminuria, both known atherosclerotic risk factors, remain present. Although more patients reach adult age, no information is still available about accelerated atherosclerosis. The aim of our study was to investigate whether GSD 1a was associated with premature atherosclerosis. In nine adolescent patients (mean age 22.7+/-3.4 years) and nine matched healthy control subjects, lipid profile, blood pressure, ankle-brachial indices, aortic distensibility and intima-media thickness (IMT) of the carotid and femoral arteries were determined. As expected, lipid profiles were significantly unfavourable in the patient group compared with the control group. No differences were found in blood pressure, ankle-brachial indices and aortic distensibility between both groups. IMT segments were comparable in both groups, with even thinner segments in the patient group. In different multivariate models, GSD 1a remained an independent predictor for a thinner IMT (R(2)=0.90; beta=-0.69; P=0.018). CONCLUSIONS glycogen storage disease type 1a is not associated with premature atherosclerosis, despite the existence of longstanding dyslipidaemia and microalbuminuria.