Comparison of TyG and Newly TyG Related Indicators for Chronic Kidney Diseases Estimation in a Chinese Population

Background

Obesity and insulin resistance (IR) are positively associated with chronic kidney disease (CKD). Previous studies have identified triglyceride-glucose index (TyG) as a valuable surrogate of insulin resistance. Recently, new indicators combining TyG and simple anthropometric indices have emerged, The objective of this study was to assess the diagnostic accuracy of TyG and newly TyG related indicators in detecting CKD and explore which indices were superior in associating with CKD in Chinese population.

Methods

Correlation test, logistic regression analysis, and receiver operating characteristic (ROC) analyses were used to evaluate the optimal cut-off and value of TyG, TyG-body mass index (TyG-BMI), TyG-waist circumference (TyG-WC), TyG-waist to height ratio (TyG-WHtR) for predicting CKD.

Results

TyG-WHtR, TyG-WC, and TyG-BMI correlated with several risk factors for CKD. After adjusting for confounders, TyG-WHtR and TyG-WC remained significantly associated with CKD, while TyG-BMI did not. The highest quartiles of TyG-WHtR and TyG-WC had 1.95- and 1.91-fold increased risk of CKD than the lowest quartiles (P<0.05). TyG-WHtR had the largest AUC (0.687) for CKD detection, followed by TyG-WC (0.669), TyG (0.652), and TyG-BMI (0.648). A united model that involved TyG-WHtR and other risk variables had higher predictive performance (AUC=0.791) than a single TyG related indicator. However, TyG had the highest OR (2.713, 95% CI, 1.446-5.090) for reduced eGFR in the fully adjusted model. A united model that involved TyG and WHtR separately had stronger predictive ability (AUC: 0.794) than the model that involved TyG-WHtR individually (AUC:0.791).

Conclusion

This study found that TyG-WHtR had a better diagnostic value in the diagnosis of CKD, compared to other TyG related indicators, but none of the TyG related indicators showed a stronger association with CKD than TyG. Further research and more refined algorithms are needed to verify these new indicators.

Estimate of reduced glomerular filtration rate by triglyceride-glucose index: insights from a general Chinese population

Objectives: Recent studies have identified triglyceride-glucose index (TyG) as a surrogate of insulin resistance. Since insulin resistance correlates with renal damage, our study aims to investigate the impact of TyG on the risk of reduced eGFR and explore its value to improve the risk stratification and prevention of reduced eGFR. Methods: This cross-sectional study included 6466 participants (mean age:59.57 years, 60.2% females) from rural areas of northeast China between September 2017 to May 2018. TyG was calculated as ln[fasting triglyceride (mg/dL)×fasting plasma glucose (mg/dL)/2]. Reduced eGFR was defined as eGFR<60ml/min per 1.73m². Results: The prevalence of reduced eGFR was 2.94%. After full adjustment, each SD increase of TyG caused 42.6% additional risk for reduced eGFR. When dividing TyG into quartiles, the top quartile had a 1.934 times risk than the bottom quartile. Furthermore, the risk of reduced eGFR increased linearly with the increment of TyG. Subgroup analysis also revealed the association was robust to several risk factors of renal damage. Finally, category-free net reclassification index (0.204, 95% CI: 0.060-0.349, p = 0.005) and integrated discrimination index (0.010, 95% CI: 0.005-0.016, p < 0.001) demonstrated the value of TyG to refine the risk stratification of reduced eGFR. Conclusion: Our work reveals the robust association between TyG and reduced eGFR. Moreover, the present study implicates the potential role of TyG as a risk indicator to optimize the prevention of reduced eGFR. Lastly, the findings also suggest the importance of simultaneous glycemic and lipid control to avoid the development and progression of reduced eGFR.

Effect of the daily ingestion of a purified anthocyanin extract from grape skin on rat serum antioxidant capacity

The aim of this work was to study the effect of the daily ingestion of a purified anthocyanin extract from red grape skin on rat serum antioxidant capacity (ORAC) and its safety for the intestinal epithelium. The study was carried out in rats orally administered with the extract for 10 days in either normal physiological conditions or exposed to a pro-oxidant chemical (CCl(4)). The oral administration of the extract significantly (P<0.05) enhanced the ORAC value of the deproteinised serum of about 50 % after 10 days of ingestion. Anthocyanin administration was also able to reverse completely the decrease in the serum ORAC activity induced by the CCl(4) treatment. Experiments with Ussing chamber mounted intestine allowed to exclude any toxicity of the extract for the intestinal epithelium. In conclusion, our results demonstrate that the purified anthocyanin extract from red grape skin enhances the total antioxidant capacity of the serum in either normal physiological condition or during oxidative stress induction, revealing a protective role against the decrease in the serum antioxidant capacity induced by a pro-oxidant compound.

Ileal apical Na+-dependent bile acid transporter ASBT is upregulated in rats with diabetes mellitus induced by low doses of streptozotocin

Increased intestinal bile acid absorption and expansion of the bile acid pool has been implicated in the hypercholesterolemia associated with diabetes mellitus. However, the molecular basis of the increase in bile acid absorption in diabetes mellitus is not fully understood. The ileal apical Na(+)-dependent bile acid transporter (ASBT) is primarily responsible for active reabsorption of the majority of bile acids. Current studies were designed to investigate the modulation of ASBT function and expression in streptozotocin (STZ)-induced diabetes mellitus in rats and to examine the effect of insulin on rat ASBT promoter by insulin. Diabetes mellitus was induced in Sprague-Dawley rats by intraperitoneal injection of low doses of STZ (20 mg/kg body wt) on five consecutive days. Human insulin (10 U/day) was given to a group of diabetic rats for 3 days before euthanasia. RNA and protein were extracted from mucosa isolated from the small intestine and ASBT expression was assessed by real-time quantitative RT-PCR and Western blotting. Our data showed that ASBT mRNA and protein expression were significantly elevated in diabetic rats. Insulin treatment of diabetic rats reversed the increase in ASBT protein expression to control levels. Consistently, ileal Na(+)-dependent [(3)H]taurocholic uptake in isolated intestinal epithelial cells was significantly increased in diabetic rats. In vitro studies utilizing intestinal epithelial Caco-2 cells demonstrated that ASBT expression and promoter activity were significantly decreased by insulin. These studies demonstrated that insulin directly influences ASBT expression and promoter activity and that ASBT function and expression are increased in rats with STZ-induced diabetes mellitus. The increase in ASBT expression may contribute to disturbances in cholesterol homeostasis associated with diabetes mellitus.

Insulin internalizes GLUT2 in the enterocytes of healthy but not insulin-resistant mice

OBJECTIVES

A physiological adaptation to a sugar-rich meal is achieved by increased sugar uptake to match dietary load, resulting from a rapid transient translocation of the fructose/glucose GLUT2 transporter to the brush border membrane (BBM) of enterocytes. The aim of this study was to define the contributors and physiological mechanisms controlling intestinal sugar absorption, focusing on the action of insulin and the contribution of GLUT2-mediated transport.

RESEARCH DESIGN AND METHODS

The studies were performed in the human enterocytic colon carcinoma TC7 subclone (Caco-2/TC7) cells and in vivo during hyperinsulinemic-euglycemic clamp experiments in conscious mice. Chronic high-fructose or high-fat diets were used to induce glucose intolerance and insulin resistance in mice.

RESULTS AND CONCLUSIONS

In Caco-2/TC7 cells, insulin action diminished the transepithelial transfer of sugar and reduced BBM and basolateral membrane (BLM) GLUT2 levels, demonstrating that insulin can target sugar absorption by controlling the membrane localization of GLUT2 in enterocytes. Similarly, in hyperinsulinemic-euglycemic clamp experiments in sensitive mice, insulin abolished GLUT2 (i.e., the cytochalasin B-sensitive component of fructose absorption), decreased BBM GLUT2, and concomitantly increased intracellular GLUT2. Acute insulin treatment before sugar intake prevented the insertion of GLUT2 into the BBM. Insulin resistance in mice provoked a loss of GLUT2 trafficking, and GLUT2 levels remained permanently high in the BBM and low in the BLM. We propose that, in addition to its peripheral effects, insulin inhibits intestinal sugar absorption to prevent excessive blood glucose excursion after a sugar meal. This protective mechanism is lost in the insulin-resistant state induced by high-fat or high-fructose feeding.