Key result
Elevated triglycerides were associated with higher plasma free thiols compared to subjects without elevated triglycerides (663 vs 619 µmol/L; p=0.002), reflecting lower systemic oxidative stress.
Why the study?
Because hyperglycemia causes oxidative stress, it remained unknown whether plasma free thiols are altered in T2DM patients without cardiovascular disease or renal function impairment, and how they relate to elevated triglycerides and VLDL.
Cross-Sectional (n=168)
Absolute Event Rate: 663% vs 619%
p-value: p=0.002
In well-controlled, non-smoking T2DM patients without cardiovascular disease, circulating free thiols are not decreased and are paradoxically higher with elevated triglycerides and large VLDL, suggesting lower systemic oxidative stress.
Free thiols appear preserved in well-controlled T2DM without complications; leaves open paradoxical TG/VLDL associations as hypothesis-generating.
Decreased circulating levels of free thiols (R-SH, sulfhydryl groups) reflect enhanced oxidative stress, which plays an important role in the pathogenesis of cardiometabolic diseases. Since hyperglycemia causes oxidative stress, we questioned whether plasma free thiols are altered in patients with type 2 diabetes mellitus (T2DM) without cardiovascular disease or renal function impairment. We also determined their relationship with elevated triglycerides and very low density lipoproteins (VLDL), a central feature of diabetic dyslipidemia. Fasting plasma free thiols (colorimetric method), lipoproteins, VLDL (nuclear magnetic resonance spectrometry), free fatty acids (FFA), phospholipid transfer protein (PLTP) activity and adiponectin were measured in 79 adult non-smoking T2DM subjects (HbA1c 51 ± 8 mmol/mol, no use of insulin or lipid lowering drugs), and in 89 non-smoking subjects without T2DM. Plasma free thiols were univariately correlated with glucose (r = 0.196, p < 0.05), but were not decreased in T2DM subjects versus non-diabetic subjects (p = 0.31). Free thiols were higher in subjects with (663 ± 84 µmol/L) versus subjects without elevated triglycerides (619 ± 91 µmol/L; p = 0.002). Age- and sex-adjusted multivariable linear regression analysis demonstrated that plasma triglycerides were positively and independently associated with free thiols (β = 0.215, p = 0.004), FFA (β = 0.168, p = 0.029) and PLTP activity (β = 0.228, p = 0.002), inversely with adiponectin (β = −0.308, p < 0.001) but not with glucose (β = 0.052, p = 0.51). Notably, the positive association of free thiols with (elevated) triglycerides appeared to be particularly evident in men. Additionally, large VLDL were independently associated with free thiols (β = 0.188, p = 0.029). In conclusion, circulating free thiols are not decreased in this cohort of non-smoking and generally well-controlled T2DM subjects. Paradoxically, higher triglycerides and more large VLDL particles are likely associated with higher plasma levels of thiols, reflecting lower systemic oxidative stress.
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Dijk et al. (2019) conducted a cross-sectional in Type 2 diabetes mellitus (n=168). Elevated triglycerides vs. Without elevated triglycerides was evaluated on Plasma free thiols (p=0.002). Elevated triglycerides were associated with higher plasma free thiols compared to subjects without elevated triglycerides (663 vs 619 µmol/L; p=0.002), reflecting lower systemic oxidative stress.
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