Uncontrolled type 1 diabetes mellitus and endothelial dysfunction in adolescents.

BACKGROUND Diabetes mellitus is associated with microvascular and macrovascular diseases, potentially manifested as endothelial dysfunction. In adults with type 2 diabetes the haptoglobin genotype 1-1 has been shown to have a protective role in inhibiting the development of complications. Although complications from type 1 diabetes are infrequent during childhood, endothelial dysfunction, which is an early marker of vascular complications, may occur. OBJECTIVES To evaluate endothelial function in adolescents with type 1 diabetes before the development of complications and to test for potential relationships between endothelial dysfunction and haptoglobin genotype. METHODS The study group comprised 15 adolescents with type 1 diabetes. All underwent a general physical examination, diabetes control evaluation (including HbA1c levels), endothelial function assessment and haptoglobin genotype determination. RESULTS There was a significant negative correlation between HbA1c levels and endothelial function (r = -0.48, P < 0.05), and HbA1c was significantly higher in patients with endothelial dysfunction than in those with normal endothelial function (9.9 +/- 2.2 vs. 7.7 +/- 1.0 mg/dl, P < 0.05). In addition, there was a tendency toward a positive correlation between high density lipoprotein and endothelial function (r = 0.4, P < 0.1). There was no correlation between the haptoglobin genotype and endothelial function. CONCLUSIONS These results show that even in patients without complications, uncontrolled type 1 diabetes is associated with endothelial dysfunction, which may lead to microvascular complications in the future.