Challenges in the diagnosis of insulin resistance: Focusing on the role of HOMA-IR and Tryglyceride/glucose index

Background and aimsMetabolic Syndrome (MS) prevalence is increasing worldwide in line with the growing prevalence of obesity. The underlying mechanism of MS is insulin resistance which can be diagnosed by measuring Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and Triglyceride/Glucose (TyG) Index. This review will focus on comparing studies assessing the HOMA-IR and TyG index cut-off points.MethodsWe carried out a comprehensive review of the literature using suitable keywords on the search engines of PubMed, Scopus, Research Gate, and Google Scholar in the month of October 2020.ResultsThere is a high degree of variability in determining threshold levels of HOMA-IR for defining insulin resistance. The distribution of the HOMA-IR varies according to the demographic characteristics of the subjects, such as age, sex, and race, making it difficult to estimate the optimal cut-off point. Another simpler method without requiring the use of insulin assays is TyG Index. Similar to HOMA-IR, the TyG Index cut-off point from existing data shows varying results.ConclusionThe HOMA-IR and the TyG index are simple and widely used methods for determining insulin resistance. However, an issue that arises is determining the insulin resistance cut-off point for both methods. Further studies are needed to assess the cut-off point of insulin resistance for various ethnicities associated with the risk of developing MS later in life.     

Mucosa-associated microbiota in the jejunum of patients with morbid obesity: alterations in states of insulin resistance and metformin treatment

BackgroundStool samples have been widely used to evaluate gut microbiota; however, little is known about the composition of human small intestinal microbiota and the alterations provoked by insulin resistance.ObjectiveTo describe the composition of jejunal microbiota in morbidly obese patients, as well as its link with insulin resistance and metformin treatment.SettingVirgen de la Victoria University Hospital and Regional University Hospital, Málaga, Spain.MethodsJejunal biopsies from 46 morbidly obese patients were analyzed by next-generation sequencing method. Patients were classified in the following 3 groups: low homeostasis model assessment of insulin resistance index (HOMA-IR) value, high HOMA-IR value, and metformin-treated type 2 diabetes patients (T2D-metf).ResultsRichness (q = .011) together with Proteobacteria (W = 2), Fusobacteria (W = 2), and Bacteroidetes (W = 1) phyla were significantly higher in high HOMA-IR compared with low HOMA-IR group. At family level, several differences were found between low HOMA-IR and T2D-metf group, being the most important the higher abundance of Halomonadacea in T2D-metf group (W = 22). PICRUSt analysis showed that predicted genes involved in trimethylamine-N-oxide biosynthesis pathway could be increased in jejunal microbiota of T2D-metf group compared with the low HOMA-IR group, while indole biosynthesis pathway could be increased in the low HOMA-IR group compared with the high HOMA-IR group.ConclusionAn increase in richness and an enrichment in Proteobacteria, Fusobacteria, and Bacteroidetes was observed in jejunal from morbidly obese patients with high insulin resistance. Halomonadaceae family was significantly increased in metformin-treated patients. Functional analysis of predicted metagenome suggests that trimethylamine-N-oxide biosynthesis pathway could be increased in the jejunal microbiota of T2D-meft group, while indole biosynthesis pathway could be increased in low HOMA-IR group. These results contribute to the increase in the scarce knowledge about the mucosal microbiota of the hardly accessible small intestine.     

甘油三酯与高密度脂蛋白-胆固醇比值在预测儿童代谢综合征中的意义

目的:探讨甘油三酯与高密度脂蛋白-胆固醇比值（TG/HDL-C）和稳态模型评估-胰岛素抵抗指数 （HOMA-IR）在儿童代谢综合征（MS）中的预测价值。方法:收集自2015年1月—2019年12月在天津医科大学总 医院儿科诊断为肥胖的儿童203例,测量血压、腰围,于次日空腹行口服葡萄糖耐量试验（OGTT）并检测HbA1c 、血脂等。按照儿童青少年肥胖MS的诊断标准,分为MS组67例,对照组（非MS组）136例。根据OGTT计算 HOMA-IR、松田指数、稳态模型评估-胰岛β细胞功能指数（HOMA-β）、早期胰岛素分泌指数（ΔI30/ΔG30） 、血糖曲线下面积（血糖-AUC）、胰岛素曲线下面积（胰岛素-AUC）,利用受试者工作特征（ROC）曲线评价 TG/HDL-C和HOMA-IR的特异性和灵敏性,以及两项指标联合预测与单独预测之间是否存在统计学差异。结果: 与非MS组相比, MS组TG/HDL-C比值（Z=-8.441,P=0.000）、HOMA-IR （Z=-4.476,P=0.000）升高。当 TG/HDL-C＞1.31时,其预测MS的敏感性为86.6%,特异性为84.6%。当HOMA-IR＞7.08时,预测MS的敏感性为 53.7%,特异性为77.9%。相较于单独应用HOMA-IR诊断MS,TG/HDL-C单独诊断MS（Z=3.425,P=0.000 6）,以 及TG/HDL-C联合HOMA-IR诊断MS（Z=4.481,P＜0.000 1）更具敏感性。而单独应用TG/HDL-C与TG/HDL-C联合 HOMA-IR诊断MS相比时,两者间差异无显著统计学意义。结论:TG/HDL-C单独或者TG/HDL-C联合HOMA-IR,可作 为MS的一个良好预测指标。     

An examination of sex and racial/ethnic differences in the metabolic syndrome among adults: A confirmatory factor analysis and a resulting continuous severity score

Objective

The metabolic syndrome (MetS) is typically diagnosed based on abnormalities in specific clustered clinical measures that are associated with increased risk for coronary heart disease (CHD) and Type 2 diabetes mellitus (T2DM). However, current MetS criteria result in racial/ethnic discrepancies. Our goals were to use confirmatory factor analysis (CFA) to delineate differential contributions to MetS by sub-group, and if contributions were discovered, develop sex and racial/ethnic-specific equations to calculate MetS severity.

Research Design and Methods

Using data on adults from the National Health and Nutrition Examination Survey 1999–2010, we performed a CFA of a single MetS factor that allowed differential loadings across groups, resulting in a sex and race/ethnicity-specific continuous MetS severity score.

Results

Loadings to the single MetS factor differed by sub-group for each MetS component (p < 0.001), with lower factor loadings among non-Hispanic-blacks for triglycerides and among Hispanics for waist circumference. Systolic blood pressure exhibited low factor loadings among all groups. MetS severity scores were correlated with biomarkers of future disease (high-sensitivity C-reactive-protein, uric acid, insulin resistance). Non-Hispanic-black-males with diabetics had a low prevalence of MetS but high MetS severity scores that were not significantly different from other racial/ethnic groups.

Conclusions

This analysis among adults uniquely demonstrated differences between sexes and racial/ethnic groups regarding contributions of traditional MetS components to an assumed single factor. The resulting equations provide a clinically-accessible and interpretable continuous measure of MetS for potential use in identifying adults at higher risk for MetS-related diseases and following changes within individuals over time. These equations hold potential to be a powerful new outcome for use in MetS-focused research and interventions.     

Insulin resistance and idiopathic infertility: A potential possible link

Among various health issues, infertility has been always considered as one of the major health problems. Idiopathic infertility is still a matter of debate since the underlying mechanisms stay obscure. Idiopathic infertility is related to expanded chance of metabolic syndrome components, obesity and increased risk of cardiovascular diseases. This study aimed to assess insulin resistance and serum levels of irisin as one of the adipokines in patients with idiopathic infertility. This study included 50 male patients aged 25–50 years old suffering from idiopathic infertility, together with 50 healthy individuals of matched age as controls. Patients showed significantly increased homeostasis model assessment for insulin resistance values than controls. For irisin results, idiopathic infertility patients had significantly decreased values than controls indicating the potential effect of irisin in development of insulin resistance in idiopathic infertility patients.     

Vegetarians have a lower fasting insulin level and higher insulin sensitivity than matched omnivores: A cross-sectional study

Background and aims

Potential associations of vegetarian diet patterns with fasting insulin (FI) and insulin sensitivity remain unclear. We aimed to investigate whether vegetarian diets were associated with FI and insulin sensitivity in a cross-sectional study in Chinese vegetarians and matched omnivores and then to test whether it is independent of body mass index (BMI).

Correlation between insulin resistance and white matter lesions among non-diabetic patients with ischemic stroke

Abstract

Objective: We investigated whether a correlation exists between insulin resistance and the severity of cerebral white matter lesions among non-diabetic patients with ischemic stroke.

Methods: The subjects were 105 consecutive patients without diabetes who were hospitalized due to non-cardioembolic stroke. The insulin resistance was evaluated by a homeostasis model assessment of insulin resistance (HOMA-IR). The degrees of periventricular hyperintensity (PVH) and deep and subcortical white matter hyperintensity (DSWMH) were evaluated by the brain MRI. The HOMA-IR values ≥2·5 were indicative of the insulin resistance.

Results: The presence of PVH and DSWMH were 86·7 and 83·8%, respectively. The ratio of insulin resistance increased with higher grades of PVH and DSWMH. The HOMA-IR level in grade 3 PVH was significantly higher than those in grades 0 and 1. The HOMA-IR level in grade 3 DSWMH was significantly higher than those in grades 0–2. Multiple linear regression analysis showed that HOMA-IR was significantly associated with PVH or DSWMH.

Conclusion: It was found that insulin resistance correlated with white matter lesions among non-diabetic patients with non-cardiogenic ischemic stroke.