Association of postprandial hyperglycemia with in vitro LDL oxidation in non-smoking patients with type 1 diabetes--a cross-sectional study

Cardiovascular disease is the main cause of death in patients with type 1 diabetes. Since oxidized low density lipoprotein (LDL) is considered to be a critical factor in the atherosclerotic process, the aim of our study was to assess the influence of different parameters of glycemic control on susceptibility to oxidative stress from low density lipoprotein (LDL) in patients with type 1 diabetes without microvascular or macrovascular complications. Forty patients and 33 non-diabetic individuals matched for gender, age and body mass index (BMI) were evaluated. The two groups underwent determination of lipid profile, fasting and postprandial glucose control and measurement of glycated hemoglobin (HbA1c). Spectrophotometric analysis of the LDL oxidation index was performed before and 1, 3, 6 and 24 h after the addition of copper sulfate to purified LDL fractions. The oxidation coefficient for LDL presented similar basal values in the two groups; however, at 3 h, LDL showed a higher degree of oxidation in patients with type 1 diabetes. Correlations with the metabolic control variables were significant only for postprandial glycemia. Stepwise multiple regression showed that post-prandial glycemia and sex were the significant independent variables. LDL from patients with type 1 diabetes showed high susceptibility to oxidative stress and this susceptibility was markedly related to the postprandial glucose levels. The influence of our findings on the development of chronic complications in patients with type 1 diabetes must be addressed in prospective studies.