Evaluation of surrogate markers for insulin resistance for defining metabolic syndrome in urban Indian adolescents

Association between plasma leptin/adiponectin ratio and insulin resistance indexes in prepubertal children

Objective

To assess the association between leptin/adiponectin ratio (LAR) and insulin resistance surrogates in prepubertal children.

Materials and methods

Study based on data from the Growth and Obesity Chilean Cohort Study (GOCS) involving 968 Chilean prepubertal children. Plasma insulin, leptin, and adiponectin were determined by immunoassays. Several common insulin resistance surrogates were calculated, including the homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride/HDL cholesterol index, triglyceride-glucose (TyG) index, and the TyG index corrected for body mass index (BMI; TyG-BMI) and waist circumference (WC; TyG-WC). Associations among variables were assessed using multiple linear and logistic regression analysis.

Results

There was a significant direct association between plasma leptin and LAR with BMI z-score but no association between plasma adiponectin and adiposity. After adjustments for sex and age, LAR was significantly associated with all insulin resistance surrogates (which were categorized using the 75th percentile as the cutoff point), with the TyG-WC index emerging as the surrogate with the highest magnitude of association (odds ratio [OR] 2.44, 95% confidence interval [CI] 2.05-2.9). After additional adjustment for BMI z-score, only the association between LAR and TyG-WC remained significant (OR 1.64, 95% CI 1.27-2.12).

Conclusion

Plasma leptin and LAR were strongly associated with several common insulin resistance surrogates in prepubertal children, most notably with the TyG-WC index. Associations between LAR and insulin resistance indexes were mainly driven by the effect of plasma leptin, which is also directly associated with increased adiposity.

Correlation of Surrogate Markers of Insulin Resistance with Fasting Insulin in Type 2 Diabetes Mellitus Patients: A Study of Malwa Population in Punjab, India

Context Insulin resistance (IR) and abnormal insulin secretion play a key role for the development of type 2 diabetes mellitus (DM). Aims We investigated the surrogate markers of IR, i.e., Homeostasis Model Assessment (HOMA), Quantitative Insulin Sensitivity Check Index (QUICKI), McAuley, and Fasting Insulin Resistance Index (FIRI) in type 2 DM patients. Also, fasting insulin (FI) levels were estimated in type 2 diabetics. Further, the correlation of FI with other surrogate markers of IR in type 2 DM was done. Settings and Design A hundred newly diagnosed patients with type 2 DM from Malwa population, Punjab, were considered for evaluation. Another 100 healthy individuals (age and sex-matched) were examined as controls. Methods and Material Fasting blood glucose, FI, and lipid profile were estimated, and IR was calculated using McAuley index (McA), HOMA, QUICKI, and FIRI. Statistical Analysis Used The statistical analysis was performed on the above-mentioned clinical interpretations. The Cohen's kappa test was used to affirm the agreement. Results FI levels in patients with type 2 diabetes were significantly higher (20.8 ± 9.05 µIU/L) than controls (7.93 ± 1.01 µIU/L). IR by surrogate markers was found significant in the study group. The 76% patients with type 2 diabetes ended up as resistant to insulin by FI measurement, almost equivalent to McA, 80%; HOMA, 88%; FIRI, 88%; and QUICKI, 90%. A notable correlation was highlighted between FI and McA manifesting IR ( p < 0.01, r = -0.85). We calculated the statistical correlation of FI with HOMA, QUICKI, and FIRI indices ( p < 0.01, r = 0.93; p < 0.01 r = -0.92; and p < 0.01, r = +0.93, respectively). The agreement visible from Cohen's kappa test also affirms the same ( k = 0.9 for McA). Conclusion We concluded that all the surrogate markers for IR were specific when compared with FI, but in terms of sensitivity McA was found to be more sensitive as it includes markers of dyslipidemia, which is the precipitating factor of metabolic derangements so as the IR in type 2 DM.

Pharmacokinetics, tissue distribution and excretion of a novel long-acting human insulin analogue - recombinant insulin LysArg in rats

As a novel long-acting recombinant human insulin analogue, it is necessary to carry out the preclinical research for insulin LysArg. The purpose of this study was to characterise the pharmacokinetic, tissue distribution and excretion of insulin LysArg and provide a reference for its development. Three methods were used to measure the content of insulin LysArg in biological samples after a single subcutaneous administration in rats, including radioassay, radioassay after precipitation with TCA and separation by HPLC. After Subcutaneous administration of recombinant insulin LysArg 1, 2, 4 U/kg in rats, it showed both C_max and AUC_0-t were positively correlated with the dose. In the meanwhile, after a single subcutaneous administration of recombinant insulin LysArg at 2 U/kg in rats, the amount of radioactivity in most organs was highest at 1.5 h and then decreased gradually, no accumulation was found. The highest level of insulin LysArg was observed in the kidney. Like other macromolecules, insulin LysArg was mainly excreted from urine. The study fully illustrated the pharmacokinetic pattern of insulin LysArg, provided valuable informations to support its further development about safety and toxicology.

Homeostasis Model Assessment cut-off points related to metabolic syndrome in children and adolescents: a systematic review and meta-analysis

The aim of this study was to perform a systematic review and meta-analysis of cut-off points of Homeostasis Model Assessment (HOMA-IR) to determine metabolic syndrome (MetS) in children and adolescents. A literature search was conducted in MEDLINE (via PubMed), EMBASE, Web of Science, Proquest, and Scopus databases from their inception to June 2018. Random effects models for the diagnostic odds ratio (dOR) value computed by Moses' constant for a linear model and 95% confidence intervals (CIs) were used to calculate the accuracy of the test. Hierarchical summary receiver operating characteristic curves (HSROC) were used to summarize the overall test performance. Six published studies were included in the meta-analysis that included 8732 children and adolescents. The region of HOMA-IR (i.e., dOR) associated with MetS range from 2.30 to 3.54. The pooled accuracy parameters from the studies that evaluated the diagnostic odds ratio of HOMA-IR ranged from 4.39 to 37.67.Conclusion: the HOMA-IR test may be useful for early evaluating children and adolescents with insulin resistance (IR). Furthermore, they present a good diagnostic accuracy independently of the definition of MetS used. According to the studies, the HOMA-IR cut point to avoid MetS risk ranged from 2.30 to 3.59.What is Known:• There is no consensus to define the optimal cut-off point of Homeostasis Model Assessment-Insulin Resistance in children and adolescents associated with Metabolic Syndrome.What is New:• The Homeostasis Model Assessment-Insulin Resistance test may be useful for early evaluations in children and adolescents with insulin resistance and presents a good diagnostic accuracy independently of the definition of Metabolic Syndrome used.• The Homeostasis Model Assessment-Insulin Resistance cut point to avoid Metabolic Syndrome risk ranged from 2.30 to 3.59.

Influence of LRP5 (rs556442) polymorphism on insulin resistance in healthy Iranian children and adolescents

Background/aim

Genetic aspects play a role in insulin resistance in children. In this study, for the first time, the association of LRP5 (rs556442) polymorphism and insulin resistance in Iranian children and adolescents was investigated.

Materials and methods

The study population comprises children and adolescents aged 9–18 years. Anthropometric and biochemical parameters were assessed. Insulin resistance/sensitivity was determined by the quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment-insulin resistance (HOMA-IR), insulin-to-glucose ratio, McAuley index, revised McAuley index, fasting insulin resistance index (FIRI), and Bennett’s index. LRP5 (rs566442) single nucleotide polymorphism (SNP) was identified using restriction fragment length polymorphism (RFLP). Linear regression analysis was used to determine the association between the LRP5 polymorphism (rs556442) and insulin sensitivity indexes.

Results

Significant differences were found between GG genotype vs. AG/AA genotypes for McAuley index (P = 0.049) and revised McAuley index (P = 0.044) when adjusted for interaction factors (age, sex, and puberty) in regression models. No significant association was found between LRP5 (rs566442) and other insulin resistance indexes. Also, LRP5 (rs566442) did not show a significant impact on biochemical parameters.

Conclusion

This study showed that LRP5 polymorphism (rs556442) was associated with insulin resistance in Iranian children and adolescents.

Normative range of blood biochemical parameters in urban Indian school-going adolescents

Adolescence is the most critical phase of human growth that radically alters physiology of the body and wherein any inconsistency can lead to serious health consequences in adulthood. The timing and pace at which various developmental events occur during adolescence is highly diverse and thus results in a drastic change in blood biochemistry. Monitoring the physiological levels of various biochemical measures in ample number of individuals during adolescence can call up for an early intervention in managing metabolic diseases in adulthood. Today, only a couple of studies in different populations have investigated blood biochemistry in a small number of adolescents however, there is no comprehensive biochemical data available worldwide. In view, we performed a cross-sectional study in a sizeable group of 7,618 Indian adolescents (3,333 boys and 4,285 girls) aged between 11–17 years to inspect the distribution of values of common biochemical parameters that generally prevails during adolescence and we observed that various parameters considerably follow the reported values from different populations being 3.56–6.49mmol/L (fasting glucose), 10.60–199.48pmol/L (insulin), 0.21–3.22nmol/L (C–peptide), 3.85–6.25% (HbA₁c), 2.49–5.54mmol/L (total cholesterol), 1.16–3.69mmol/L (LDL), 0.78–1.85mmol/L (HDL), 0.33–2.24mmol/L (triglycerides), 3.56–11.45mmol/L (urea), 130.01–440.15μmol/L (uric acid) and 22.99–74.28μmol/L (creatinine). Barring LDL and triglycerides, all parameters differed significantly between boys and girls (p< 0.001). Highest difference was seen for uric acid (p = 1.3 x10^-187) followed by C–peptide (p = 6.6 x10^-89). Across all ages during adolescence, glycemic and nitrogen metabolites parameters varied markedly with gender. Amongst lipid parameters, only HDL levels were found to be significantly associated with gender following puberty (p< 0.001). All parameters except urea, differed considerably in obese and lean adolescents (p< 0.0001). The present study asserts that age, sex and BMI are the essential contributors to variability in blood biochemistry during adolescence. Our composite data on common blood biochemical measures will benefit future endeavors to define reference intervals in adolescents especially when the global availability is scarce.

Body Composition, Metabolic Characteristics, and Insulin Resistance in Obese and Nonobese Women with Polycystic Ovary Syndrome

Objectives:

The objective was to compare body composition, metabolic characteristics, and insulin resistance between obese (body mass index [BMI] ≥25 kg/m²) polycystic ovary syndrome (PCOS) and nonobese PCOS (BMI <25 kg/m²) women and their age- and BMI-matched controls.

Materials and Methods:

A total of 81 PCOS women (Rotterdam criteria) (obese – 42; nonobese – 39) and 86 controls (obese – 42; nonobese –44) were recruited in this cross-sectional study. All women underwent a detailed assessment of clinical, anthropometric, and metabolic parameters, insulin resistance indices, and body composition measurements with visceral adipose tissue assessment (VAT) (dual-energy X-ray absorptiometry scan).

Results:

Of PCOS women, 27% (80% – obese PCOS; 20% – nonobese PCOS) were diagnosed with metabolic syndrome (International Diabetes Federation criteria), 35% of PCOS women (46% – obese PCOS; 54% – nonobese PCOS) had impaired glucose tolerance, and 7% of PCOS women (2/3^rd – obese PCOS; 1/3^rd – nonobese PCOS) had diabetes mellitus. Insulin resistance was seen in about 80% in obese PCOS women and 20% in nonobese PCOS women based on various insulin resistance indices such as fasting insulin (≥12.2 μU/ml), Homeostasis Model Assessment-Insulin Resistance (≥2.5), and Quantitative Insulin Sensitivity Check Index (<0.33). Total body fat, estimated (Est.) VAT, and corrected Est. VAT (corrected for body weight) were significantly increased (P = 0.0001) in both obese and nonobese PCOS women when compared to those of their age- and BMI-matched controls. However, corrected Est. VAT (corrected for body weight) was not significantly different between obese and nonobese PCOS women.

Conclusion:

Both obese and nonobese PCOS women when compared with their age- and BMI-matched controls were metabolically worse and had more visceral adiposity. Nonobese PCOS poses similar risk as that of obese PCOS in having similar amount of VAT (corrected for body weight).

Association of Acanthosis Nigricans and Insulin Resistance in Indian Children and Youth - A HOMA2-IR Based Cross-Sectional Study

Introduction:

The American Diabetes Association includes acanthosis nigricans (AN) as an indicator of diabetes mellitus risk in overweight youth entering puberty. Some argue that AN is not an independent predictor of insulin resistance (IR), when body mass index (BMI) is controlled for. There is a paucity of studies on the association of AN and IR among children and young adults from India. Homeostatic model assessment-IR (HOMA2-IR), a computerized updated model, which is supposed to be superior to HOMA1-IR, has rarely been used for quantification of IR.

Methods:

Sixty cases (irrespective of BMI), aged 2–24 years with AN, and 30 age- and sex-matched normal weight controls were included. A thorough clinical examination and grading of AN was done. BMI, fasting glucose levels, and fasting insulin levels were measured for all. HOMA-IR calculator V.2.2.3 was used to calculate IR. Those with HOMA 2-IR >1.8 were considered insulin-resistant. Lifestyle modifications were advised for patients with IR.

Results:

The mean HOMA2-IR value in cases and controls was 2.422 and 1.322, respectively, which was statistically significant. Overweight and obese cases had 2.5 and 11.25 times higher risk of having IR, respectively, by logistic regression. The association of AN with IR was found to be statistically significant in normal weight cases when compared with controls (P = 0.045). Grade 4 of neck severity (P = 0.007), Grade 3 of neck texture (P = 0.001), and Grade 4 of axillary severity (P = 0.001) of AN were found to be significantly associated with IR.

Limitations:

The relatively small sample size may not reflect the accuracy of AN as a marker of IR.

Conclusion:

Acanthosis nigricans is associated with IR in both normal and obese. We propose that all children, adolescents, and youth with AN be screened for IR irrespective of BMI. Early identification and prompt lifestyle interventions may prevent or delay the onset of diabetes later.

Limitations of insulin resistance assessment in polycystic ovary syndrome

BACKGROUND

Though insulin resistance (IR) is common in polycystic ovary syndrome (PCOS), there is no agreement as to what surrogate method of assessment of IR is most reliable.

SUBJECTS AND METHODS

In 478 women with PCOS, we compared methods based on fasting insulin and either fasting glucose (HOMA-IR and QUICKI) or triglycerides (McAuley Index) with IR indices derived from glucose and insulin during OGTT (Belfiore, Matsuda and Stumvoll indices).

RESULTS

There was a strong correlation between IR indices derived from fasting values HOMA-IR/QUICKI, r = -0.999, HOMA-IR/McAuley index, r = -0.849 and between all OGTT-derived IR indices (e.g. r = -0.876, for IRI/Matsuda, r = -0.808, for IRI/Stumvoll, and r = 0.947, for Matsuda/Stumvoll index, P < 0.001 for all), contrasting with a significant (P < 0.001), but highly variable correlation between IR indices derived from fasting vs OGTT-derived variables, ranging from r = -0.881 (HOMA-IR/Matsuda), through r = 0.58, or r = -0.58 (IRI/HOMA-IR, IRI/QUICKI, respectively) to r = 0.41 (QUICKI/Stumvoll), and r = 0.386 for QUICKI/Matsuda indices. Detailed comparison between HOMA-IR and IRI revealed that concordance between HOMA and IRI was poor for HOMA-IR/IRI values above 75th and 90th percentile. For instance, only 53% (70/132) women with HOMA-IR >75th percentile had IRI value also above 75th percentile. There was a significant, but weak correlation of all IR indices with testosterone concentrations.

CONCLUSIONS

Significant number of women with PCOS can be classified as being either insulin sensitive or insulin resistant depending on the method applied, as correlation between various IR indices is highly variable. Clinical application of surrogate indices for assessment of IR in PCOS must be therefore viewed with an extreme caution.

INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN 1 PREDICTS INSULIN SENSITIVITY AND INSULIN AREA-UNDER-THE-CURVE IN OBESE, NONDIABETIC ADOLESCENTS

OBJECTIVE

To compare fasting insulin-like growth factor binding protein 1 (IGFBP-1) to other fasting indices as a surrogate marker of insulin sensitivity and resistance calculated from a 3-hour oral glucose tolerance test (oGTT).

METHODS

Fasting IGFBP-1 and oGTT were performed at 0 (n = 77), 52 (n = 54), and 100 (n = 38) weeks in a study investigating metformin treatment of obesity in adolescents. Insulin area-under-the-curve (IAUC) and the composite insulin sensitivity index (CISI) calculated from the oGTT were compared to fasting IGFBP-1, homeostasis model assessment-insulin resistance, and corrected insulin release at the glucose peak (CIRgp).

RESULTS

IGFBP-1 and the ratio of IGFBP-1 to fasting insulin were significantly correlated with indices based on timed sampling, including IAUC, CISI, and CIRgp. In addition, a significant effect of IGFBP-1, but not IGFBP-1 to insulin at time zero, was observed for IAUC and CISI.

CONCLUSION

Our results indicate that fasting IGFBP-1 may be a useful marker of insulin sensitivity and secretion.