Circadian Rhythm of Subspecies of Low-Density Lipoprotein-Cholesterol and High-Density Lipoprotein-Cholesterol in Healthy Subjects and Patients with Type 2 Diabetes

Acute Statin Withdrawal Does not Interfere With the Improvements of a Session of Exercise in Postprandial Metabolism

BACKGROUND

The risk for atherogenic plaque formation is high after ingestion of meals in individuals with high blood lipid levels (ie, dyslipidemia). Statins and exercise reduce the rise of blood triglyceride concentrations after a meal, but the effect of their combination is unclear.

METHODS

In a randomized crossover design, 11 individuals with dyslipidemia and metabolic syndrome treated with statins underwent a mixed-meal (970 ± 111 kcal, 24% fat, and 34% carbohydrate) tolerance test. Plasma lipid concentrations, fat oxidation, glucose, and glycerol kinetics were monitored immediately prior and during the meal test. Trials were conducted with participants under their habitual statin treatment and 96 hours after blinded statin withdrawal. Trials were duplicated after a prolonged bout of low-intensity exercise (75 minutes at 53 ± 4% maximal oxygen consumption) to study the interactions between exercise and statins.

RESULTS

Statins reduced postprandial plasma triglycerides from 3.03 ± 0.85 to 2.52 ± 0.86 mmol·L-1 (17%; P = .015) and plasma glycerol concentrations (ie, surrogate of whole-body lipolysis) without reducing plasma free fatty acid concentration or fat oxidation. Prior exercise increased postprandial plasma glycerol levels (P = .029) and fat oxidation rates (P = .024). Exercise decreased postprandial plasma insulin levels (241 ± 116 vs 301 ± 172 ρmol·L-1; P = .026) but not enough to increase insulin sensitivity (P = .614). Neither statins nor exercise affected plasma glucose appearance rates from exogenous or endogenous sources.

CONCLUSIONS

In dyslipidemic individuals, statins reduce blood triglyceride concentrations after a meal, but without limiting fat oxidation. Statins do not interfere with exercise lowering the postprandial insulin that likely promotes fat oxidation. Last, statins do not restrict the rates of plasma incorporation or oxidation of the ingested glucose.

Accuracy of Small Dense Low-density Lipoprotein-cholesterol Concentration Estimated via Sampson's Equation in Healthy Subjects and Patients with Diabetes

AIM

Sampson et al. proposed a method to calculate small dense low-density lipoprotein-cholesterol (sdLDL-C) concentrations using common lipid measurements, but its accuracy remains unresolved. We examined the difference between Sampson's equation and direct measurement in patients with diabetes.

METHODS

sdLDL-C was measured directly by our established homogeneous assay and estimated by Sampson's equation in patients with diabetes (n=1542) and healthy control subjects (n=673). Large-buoyant (lb)LDL-C was estimated using triglycerides and LDL-C, and sdLDL-C was obtained by subtracting lbLDL-C from LDL-C. The effect of fasting/nonfasting state or lipid-lowering drug therapy on sdLDL-C values was also examined in 30 and 43 patients with diabetes, respectively.

RESULTS

The coefficient of determination (R2) between calculated sdLDL-C and direct measurement was 0.73 and 0.61 for healthy controls and patients with diabetes, respectively. The R2 between calculated sdLDL-C and nonHDL-C or apolipoprotein B was 0.64 and 0.65, respectively. Calculated sdLDL-C was 4-5 mg/dl or 17%-18% higher than the direct measurement. The lower the plasma lipids, especially sdLDL-C, the greater the dissociation between the two methods. Sampson sdLDL-C was also found to give a positive bias when calculated for the nonfasting samples. Statins and pemafibrate significantly reduced sdLDL-C, but their therapeutic effect was underestimated by 5 mg/dl (24%) via Sampson's equation.

CONCLUSIONS

The correlation between Sampson's equation and direct measurements of sdLDL-C was reduced in patients with diabetes. Furthermore, the correlations with nonHDL-C and apolipoprotein B were even higher than those with direct sdLDL-C. The accuracy of Sampson's equation decreased with lower sdLDL-C concentrations and was also influenced by diet.

Elevated postprandial triglyceride-rich lipoproteins in patients with diabetes and stable coronary artery disease correlated with early renal damage and systemic inflammation

BACKGROUND

Dyslipidaemia is key in the development of coronary heart disease (CHD) in patients with diabetes mellitus (DM). Accumulated evidence supports that diabetic nephropathy increases the mortality risk of patients with CHD, while the influence of diabetic dyslipidaemia on renal damage in patients with DM and CHD remains unknown. Moreover, recent data indicate that postprandial dyslipidaemia has predictive value in terms of CHD prognosis, especially in patients with DM. The study aimed to determine the relationship of triglyceride-rich lipoproteins (TRLs) after daily Chinese breakfast on systemic inflammation and early renal damage in Chinese patients with DM and SCAD.

METHODS

Patients with DM diagnosed with SCAD while in the Department of Cardiology of Shengjing Hospital from September 2016 to February 2017 were enrolled in this study. Fasting and 4-h postprandial blood lipids, fasting blood glucose, glycated haemoglobin, urinary albumin-to-creatinine ratio (UACR), serum interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) concentrations, and other parameters were measured. Fasting and postprandial blood lipid profiles and inflammatory cytokines were analysed using a paired t-test. The association between variables was analysed using Pearson or Spearman bivariate analysis. P < 0.05 was considered to be statistically significant.

RESULTS

The study enrolled 44 patients in total. Compared with fasting state, postprandial total cholesterol high-density lipoprotein-cholesterol (HDL-C),low-density lipoprotein-cholesterol (LDL-C) and non-high-density lipoprotein-cholesterol (non-HDL-C) all showed no significant change. Postprandial serum triglyceride (TG) concentration increased significantly compared with that at fasting (1.40 ± 0.40 vs. 2.10 ± 0.94 mmol/L, P < 0.001), as did serum remnant lipoprotein-cholesterol (RLP-C) (0.54 ± 0.18 mmol/L vs. 0.64 ± 0.25 mmol/L). Pearson analysis revealed that serum TG and RLP-C positively correlated before and after breakfast. Moreover, during fasting, positive correlations were observed between TG and serum IL-6, TNF-α, and UACR. Positive correlations were observed between RLP-C and IL-6, UACR under fasting condition, while both TG and RLP-C were positively correlated with postprandial serum IL-6, TNF-α, and UACR concentrations. Finally, positive correlations were observed between UACR and IL-6 and TNF-α concentration under both fasting and postprandial conditions.

CONCLUSIONS

An increase in postprandial TRLs was observed in Chinese patients with DM and SCAD after daily breakfast, and this increase may be related to early renal injury via the induction of systemic inflammation.