Use of the triglyceride to HDL cholesterol ratio for assessing insulin sensitivity in overweight and obese children in rural Appalachia

Metabolically Healthy Obesity: Are Interventions Useful?

PURPOSE OF REVIEW

This review aims to detail the current global research state of metabolically healthy obesogenesis with regard to metabolic factors, disease prevalence, comparisons to unhealthy obesity, and targeted interventions to reverse or delay progression from metabolically healthy to unhealthy obesity.

RECENT FINDINGS

As a long-term condition with increased risk of cardiovascular, metabolic, and all-cause mortality risks, obesity threatens public health on a national level. The recent discovery of metabolically healthy obesity (MHO), a transitional condition during which obese persons carry comparatively lower health risks, has added to confusion about the true effect of visceral fat and subsequent long-term health risks. In this context, the evaluation of fat loss interventions, such as bariatric surgery, lifestyle changes (diet/exercise), and hormonal therapies require re-evaluation in light of evidence that progression to high-risk stages of obesity relies on metabolic status and that strategies to protect the metabolism may be useful in the prevention of metabolically unhealthy obesity. Typical calorie-based exercise and diet interventions have failed to reduce the prevalence of unhealthy obesity. Holistic lifestyle, psychological, hormonal, and pharmacological interventions for MHO, on the other hand, may at least prevent progression to metabolically unhealthy obesity.

Single Point Insulin Sensitivity Estimator (SPISE) As a Prognostic Marker for Emerging Dysglycemia in Children with Overweight or Obesity

The single point insulin sensitivity estimator (SPISE) is a recently developed fasting index for insulin sensitivity based on triglycerides, high density lipoprotein cholesterol, and body mass index. SPISE has been validated in juveniles and adults; still, its role during childhood remains unclear. To evaluate the age- and sex-specific distribution of SPISE, its correlation with established fasting indexes and its application as a prognostic marker for future dysglycemia during childhood and adolescence were assessed. We performed linear modeling and correlation analyses on a cross-sectional cohort of 2107 children and adolescents (age 5 to 18.4 years) with overweight or obesity. Furthermore, survival analyses were conducted upon a longitudinal cohort of 591 children with overweight/obesity (1712 observations) with a maximum follow-up time of nearly 20 years, targeting prediabetes/dysglycemia as the end point. The SPISE index decreased significantly with age (−0.34 units per year, p < 0.001) among children and adolescents with overweight and obesity. Sex did not have an influence on SPISE. There was a modest correlation between SPISE and established fasting markers of insulin resistance (R = −0.49 for HOMA-IR, R = −0.55 for QUICKI-IR). SPISE is a better prognostic marker for future dysglycemia (hazard ratio (HR) 3.47, 95% confidence interval (CI) 1.60−7.51, p < 0.01) than HOMA-IR and QUICKI-IR (HR 2.44, 95% CI 1.24−4.81, p < 0.05). The SPISE index is a surrogate marker for insulin resistance predicting emerging dysglycemia in children with overweight or obesity, and could, therefore, be applied to pediatric cohorts that lack direct insulin assessment.

Comparison of Lipid-Derived Markers for Metabolic Syndrome in Youth: Triglyceride/HDL Cholesterol Ratio, Triglyceride-Glucose Index, and non-HDL Cholesterol

Triglyceride/high-density lipoprotein (HDL) cholesterol ratio (TG/HDL-C), triglyceride-glucose index (TyG), and non-HDL cholesterol level (non-HDL-C) have been proposed as surrogate markers for predicting metabolic syndrome (MetS). This study investigated whether these lipid-derived surrogate markers can predict MetS in Korean children and adolescents. Data from 1,814 participants were analyzed from the 2013-2016 Korean National Health and Nutrition Examination Survey. MetS was defined using three sets of criteria: Cook et al. (MetS1), de Ferranti et al. (MetS2), and the International Diabetes Federation (MetS3). The prevalence of MetS1, MetS2, and MetS3 was 4.6%, 11.3%, and 2.7%, respectively. In receiver operating characteristic curve analysis of MetS and lipid-derived surrogate markers, TG/HDL-C (0.937 for MetS1, 0.894 for MetS2, and 0.897 for MetS3) had the largest area under the curve (AUC), followed by TyG (0.906 for MetS1, 0.864 for MetS2, and 0.887 for MetS3), and non-HDL-C (0.752 for MetS1, 0.708 for MetS2, and 0.703 for MetS3) (all P < 0.001). The cutoff values for detecting MetS with TG/HDL-C, TyG, and non-HDL-C were 2.64, 8.52, and 111.6 for MetS1; 2.23, 8.47, and 110.7 for MetS2; and 2.64, 8.74, and 110.8 for MetS3, respectively. In conclusion, TG/HDL-C and TyG were similarly predictive of MetS. We propose using TG/HDL-C and TyG as surrogate markers for assessing MetS in Korean children and adolescents.

Early testing of insulin resistance: a tale of two lipid ratios in a group of 5th graders screened by the Coronary Artery Risk Detection in Appalachian Communities Project (CARDIAC Project)

BACKGROUND

In West Virginia (WV), 47% of fifth-grade children are either overweight or obese. There is no clear consensus regarding the definition of insulin resistance in children, and directly measuring insulin on the population level is costly. Two proposed measures examined further in this study include triglyceride (TRIG)/high-density lipoprotein cholesterol (HDL-C) ratio and TRIG/low-density lipoprotein (LDL-C) ratio. The purpose of this study is to examine the relationship between TRIG/HDL-C ratio, TRIG/LDL-C ratio and insulin resistance in fifth-graders with acanthosis nigricans (AN).

METHODS

Between 2007 and 2016, 52,545 fifth-grade students in WV were assessed for AN. Fasting glucose and insulin levels were collected only for a sub-group of students who were AN-positive and was used to determine insulin resistance using the Homeostatic Model for Insulin Resistance (HOMA-IR) equation. Statistical analysis included t tests and logistic regression with receiver operating characteristic curves.

RESULTS

Of the students assessed for AN, 4.5% (n = 2360) tested positive. The prevalence of insulin resistance was 79% (n = 814) among 1030 with AN and complete HOMA-IR. TRIG/HDL-C ratio and TRIG/LDL-C ratio were significantly associated with insulin resistance (TRIG/HDL-C:Est. = 0.36, P < 0.0001, AUC = 0.68; TRIG/LDL-C: Est. = 0.87, P < 0.0001, AUC = 0.69). Multivariate analysis showed that increased body mass index (Est. = 0.05, P < 0.0001), gender (Est. = 0.49, p < 0.0001) and TRIG/HDL-C ratio (Est. = 0.21, P < 0.0001) were significantly associated with insulin resistance.

CONCLUSIONS

TRIG/HDL-C is a better surrogate marker of insulin resistance in AN-positive children compared to TRIG/LDL-C ratio; so, on a population-level, cholesterol rather than insulin may be obtained for preliminary testing of early insulin resistance in children.

Inappropriate Use of Homeostasis Model Assessment Cutoff Values for Diagnosing Insulin Resistance in Pediatric Studies

Background

Assessing pediatric patients for insulin resistance is one way to identify those who are at a high risk of developing type 2 diabetes mellitus. The homoeostasis model assessment (HOMA) is a measure of insulin resistance based on fasting blood glucose and insulin levels. Although this measure is widely used in research, cutoff values for pediatric populations have not been established.

Objective

To assess the validity of HOMA cutoff values used in pediatric studies published in peer-reviewed journals.

Methods

Studies published from January 2010 to December 2015 were identified through MEDLINE. Initial screening of abstracts was done to select studies that were conducted in pediatric populations and used HOMA to assess insulin resistance. Subsequent full-text review narrowed the list to only those studies that used a specific HOMA score to diagnose insulin resistance. Each study was classified as using a predetermined fixed HOMA cutoff value or a cutoff that was a percentile specific to that population. For studies that used a predetermined cutoff value, the references cited to provide evidence in support of that cutoff were evaluated.

Results

In the 298 articles analyzed, 51 different HOMA cutoff values were used to classify patients as having insulin resistance. Two hundred fifty-five studies (85.6%) used a predetermined fixed cutoff value, but only 72 (28.2%) of those studies provided a reference that supported its use. One hundred ten studies (43%) that used a fixed cutoff either cited a study that did not mention HOMA or provided no reference at all. Tracing of citation history indicated that the most commonly used cutoff values were ultimately based on studies that did not validate their use for defining insulin resistance.

Conclusion

Little evidence exists to support HOMA cutoff values commonly used to define insulin resistance in pediatric studies. These findings highlight the importance of validating study design elements when training medical students and novice investigators. Using available data to generate population ranges for HOMA would improve its clinical utility.

Branched Chain Amino Acids, Androgen Hormones, and Metabolic Risk Across Early Adolescence: A Prospective Study in Project Viva

OBJECTIVE

This study aimed to examine the associations of two obesity-related metabolite patterns with changes in metabolic biomarkers during early adolescence.

METHODS

Multivariable linear regression was used to examine associations of branched chain amino acid (BCAA) and androgen hormone patterns with changes in glycemia (fasting glucose, insulin, homeostatic model assessment of insulin resistance), adipokines (leptin, adiponectin), inflammation (C-reactive protein, interleukin-6), lipid profile, and blood pressure during ∼5 years of follow-up among 213 children aged 6 to 10 years at baseline. Covariates included baseline age, pubertal status, biomarker level, and BMI percentile, and age at follow-up. Interactions with sex and baseline BMI percentile were also considered.

RESULTS

The median age at baseline was 7.7 years; 48.8% were boys. In adjusted models, each 1 unit of the BCAA pattern corresponded with a 4.82 (95% CI: 0.92 to 8.71) mg/dL decrease in fasting glucose in boys. In girls, the BCAA pattern was associated with an increase in triglycerides (4.17 [0.03 to 8.32] mg/dL). The androgen pattern was associated with decreased leptin (-2.35 [-4.34 to -0.35] ng/dL) and increased C-reactive protein (0.28 [0.03 to 0.54] mg/dL) in girls. These relationships did not differ by baseline BMI percentile.

CONCLUSIONS

The BCAA and androgen hormone metabolite patterns are related to changes in metabolic parameters in a sex-specific manner during early adolescence.