In vivo oxidizability of LDL in type 2 diabetic patients in good and poor glycemic control

Abstract

We aimed to determine if increased non-enzymatic glycosylation of the LDL was sufficient to increase the susceptibility to in vivo oxidation of the LDL particles. Twenty-two type 2 diabetic patients (11 males and 11 females) were included in this study. They were enrolled on the basis of good [glycated hemoglobin (HbA 1c ) < 7%] and poor glycemic control [(HbA 1c ) > 8%]. LDL were isolated by sequential ultracentrifugation and analyzed by capillary electrophoresis (CE) for diene conjugate content and for electronegativity. The glyc-LDL levels were increased in all diabetic type 2 patients, peaking in the diabetic subjects in poor diabetic control (17.3 ± 8.07%). The LDL content of diene conjugates was similar between the two groups (6.65 ± 0.77% for the patients with good glycemic control versus 6.88 ± 0.74% for those with poor glycemic control; P = 0.49) as was the electrophoretic mobility ((−1.14544 ± 0.089) × 10 −4 cm 2 /(V s) for the patients with good glycemic control and (−1.13666 ± 0.073) × 10 −4 cm 2 /(V s) for those with poor glycemic control; P = 0.80).The susceptibility to in vivo oxidation of LDL from type 2 diabetic patients in poor glycemic control did not differ from that of well-controlled diabetic patients. LDL glycosylation was not able to increase the oxidizability of LDL in the diabetic patients with poor glycemic control.

Electronegative low‐density lipoprotein subfraction from type 2 diabetic subjects is proatherogenic and unrelated to glycemic control

“…Moreover, LDL(−) proportion was not modified after glycemic optimization. This observation disagrees with previous studies performed by our group with type 1 diabetic patients [8,23] but concurs with data reported by Zhang et al [31] and Gambino et al [32] on type 2 diabetic subjects. Several factors, such as age, disease duration or underlying atherosclerosis [8] could be involved in this different response.…”

Relation between insulin resistance and fast-migrating LDL subfraction as characterized by capillary isotachophoresis

“…In type 1 diabetes, nonenzymatic glycosylation has been shown to contribute to the increased proportion of LDL( Ϫ ): glycemic optimization decreased both the glycated LDL and the proportion of LDL( Ϫ ) (3,4). However, in type 2 diabetes, glycemic control decreased glycated LDL but had no significant effects on the proportion of LDL( Ϫ ) (4,5). It is not clear whether or not insulin resistance contributes to LDL( Ϫ ) generation in type 2 diabetes.…”

“…Both type 1 and type 2 diabetes have been shown to have increased glycated LDL and a greater proportion of the LDL(Ϫ) fraction (3,4). However, glycemic control reduced LDL(Ϫ) in type 1 diabetes but not in type 2 diabetes (3)(4)(5). This encouraged us to examine the possibility of an association between insulin resistance and LDL(Ϫ).…”

Diabetes and increased lipid peroxidation are associated with systemic inflammation even in well-controlled patients

“…A limitation of many studies evaluating diabetic individuals is the lack of attention concerning metabolic and dyslipidemic status, not separating the patients based on dyslipidemia and controlled/poorly controlled type 2 diabetes mellitus, based on recent and updated HbA 1c levels (Cakatay, 2005; Gambino et al, 2004; Hussein et al, 2007; Kostolanska, Jakus, & Barak, 2009; Rytter et al, 2009). We analyzed the DM patients as separate groups based on the quality of metabolic control.…”