The Triglycerides-Glucose Index Shows a Stronger Correlation with Serum Adiponectin Levels than Homeostasis Model Assessment of Insulin Resistance and Quantitative Insulin Sensitivity Check Index

Purpose: To evaluate the association between diverse surrogate markers of insulin resistance and adiponectin concentrations. Methods: Four hundred healthy participants were included. Two different cohorts were formed according to the body mass index (BMI) values. Group 1 (n = 200) consisted of individuals with normal BMI values (18.50-24.99 kg/m2), whereas in Group 2 (n = 200) there were overweight or obese individuals (BMI ≥25.00 kg/m2). Homeostasis model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and triglycerides-glucose index (TyG) were calculated. Serum adiponectin levels were measured by ELISA. A correlation analysis was performed to assess the association between serum adiponectin and HOMA-IR, QUICKI, and TyG. Results: Participants in Group 2 were older (age in years: Group 1, 33.3 ± 6.8 vs. Group 2, 36.4 ± 7.0, P < 0.001). There was no gender difference between groups. Overweight or obese participants had higher BMI, waist circumference, fat mass, fat ratio, fasting plasma glucose, fasting plasma insulin, triglycerides, total cholesterol, and low-density lipoprotein cholesterol values, whereas high-density lipoprotein cholesterol was higher in participants with normal BMI measures. Overweight or obese subjects were more insulin resistant (higher TyG index and HOMA-IR) and less insulin sensitive (lower QUICKI), P < 0.001 for all. Serum adiponectin levels were lower in Group 2 (serum adiponectin in ng/mL: Group 1, 11,880 ± 6838 vs. Group 2, 9115 ± 5766, P < 0.001). The correlation between TyG index and adiponectin was stronger than the correlation between QUICKI and adiponectin, and HOMA-IR and adiponectin (r for TyG and adiponectin -0.408, r for QUICKI and adiponectin 0.394, r for HOMA-IR and adiponectin -0.268, respectively, P < 0.001 for all correlations). Conclusions: TyG has a stronger association with adiponectin than HOMA-IR and QUICKI.

Evaluation of Triglyceride Glucose Index and Homeostasis Model of Insulin Resistance in Patients with Polycystic Ovary Syndrome

PURPOSE

To use the triglyceride glucose (TyG) index to evaluate insulin resistance (IR) in patients with polycystic ovary syndrome (PCOS) and to explore alternative indicators for early identification of IR.

PATIENTS AND METHODS

This study included 114 patients with PCOS and 61 healthy volunteers. Pearson or Spearman correlations were calculated to compare the association between the TyG index and triglyceride glucose body mass index (TyG-BMI) with homeostatic model assessment for IR (HOMA-IR), homeostasis model assessment for β-cell function (HOMA-β), quantitative insulin sensitivity check index (QUICKI), and fasting glucose-to-insulin ratio (FG-IR). The receiver operating characteristic (ROC) curve was used to evaluate the sensitivity and specificity of the TyG index and TyG-BMI in identifying IR (defined as HOMA-IR ≥2.5) in patients with PCOS.

RESULTS

Correlation analyses revealed that the TyG index of the PCOS group was positively correlated with HOMA-IR (r=0.515, P<0.01) and HOMA-β (r=0.348, P<0.01), but negatively correlated with QUICKI (r=-0.532, P<0.01) and FG-IR (r=-0.394, P<0.01). The ROC curve of IR defined by HOMA-IR showed that the AUC value of TyG-BMI was the highest, at 0.796 (95% confidence interval (CI): 0.710-0.866, P<0.001) when the cut-off point was 191.53, with 85.3% sensitivity and 73.9% specificity values. For the TyG index, the AUC was 0.781 (95% CI: 0.693-0.853, P<0.001) when 8.51 was the cut-off point, with a sensitivity of 63.2% and specificity of 87.0%.

CONCLUSION

This study found that the TyG index and TyG-BMI performed better than traditional lipid ratios, such as triglycerides/high density lipoprotein cholesterol (TG/HDL-C), in predicting IR and may be used as markers of IR in Chinese patients with PCOS.

Effect of curative parathyroidectomy on insulin resistance

BACKGROUND

Primary hyperparathyroidism (PHPT) is characterized by inappropriately elevated serum parathyroid hormone (PTH) level despite elevated serum calcium. Insulin resistant is the basic pathophysiology, behind the higher prevalence of diabetes mellitus in patients with PHPT. However, the improvement in insulin resistance (IR) after curative parathyroidectomy (CPTX) has not been established yet, as the study results are conflicting.

MATERIALS AND METHODS

In this prospective interventional study, ten patients with mild PHPT (Group 1) and another ten patients with moderate to severe PHPT (Group 2) were undergone CPTX. The IR was assessed by homeostasis model assessment-IR (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), fasting plasma glucose (FPG), and fasting serum insulin (FSI), before and 3 months after CPTX.

RESULTS

There was no significant change of FPG and FSI, before and after CPTX in Group 1 (P = 0.179 and P = 0.104) and Group 2 (P = 0.376 and P = 0.488). Before surgery, HOMA-IR was higher, and QUICKI was significantly lower, in both Group 1 (P = 0.058 and P = 0.009) and Group 2 (P = 0.023 and P = 0.005) as compared to published normal reference mean, with no significant difference between the groups. Three months after surgery HOMA-IR increased further and QUICKI remained unchanged as compared to baseline, in both Group 1 (P = 0.072 and 0.082) and Group 2 (P = 0.54 and 0.56), but statistically insignificant.

CONCLUSION

IR remained unchanged after CPTX in mild as well as moderate to severe PHPT. Asymptomatic PHPT with abnormal IR should not be used as criteria for parathyroidectomy.

Association of Serum Magnesium Deficiency with Insulin Resistance in Type 2 Diabetes Mellitus

Background:

Insulin resistance (IR) is the key pathophysiological defect that leads to the development of type 2 diabetes mellitus. The purpose of this study was to estimate serum magnesium level and insulin sensitivity indices among type 2 diabetes mellitus patients and to see an association between them.

Methods:

This study was carried out among 38 type 2 diabetic patients and forty age and sex matched controls. Serum fasting glucose, magnesium, insulin, urea, and creatinine levels were estimated. Insulin sensitivity indices, homeostasis model assessment for insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) levels were calculated as per formulae.

Results:

A highly significant low serum magnesium level was found in diabetic subjects as compared to the controls. Statistically significant high HOMA levels (>2.6) and low QUICKI levels (<0.33) were found among the case group. An inverse, statistically significant correlation was found between serum magnesium and fasting insulin level. A highly statistically significant inverse correlation was found between serum magnesium and HOMA level, and a positive correlation was found between serum magnesium and QUICKI level, that is, serum magnesium level decreases with increase in IR. A strong association was also found between fasting serum insulin level and insulin sensitivity indices.

Conclusion:

This study showed a lower serum magnesium level in diabetic patients compared to control. A strong association was also found between serum magnesium level and insulin sensitivity indices. For proper management of type 2 diabetes, it may, therefore, be necessary to treat hypomagnesemia in these patients.

Lower serum magnesium concentration is associated with diabetes, insulin resistance, and obesity in South Asian and white Canadian women but not men

Background

A large proportion of adults in North America are not meeting recommended intakes for magnesium (Mg). Women and people of South Asian race may be at higher risk for Mg deficiency because of lower Mg intakes relative to requirements and increased susceptibility to diabetes, respectively.

Objective

This study compared serum Mg concentrations in South Asian (n=276) and white (n=315) Canadian women and men aged 20–79 years living in Canada's Capital Region and examined the relationship with diabetes, glucose control, insulin resistance, and body mass index.

Results

Serum Mg concentration was lower in women of both races and South Asians of both genders. Racial differences in serum Mg were not significant after controlling for use of diabetes medication. A substantial proportion of South Asian (18%) and white (9%) women had serum Mg <0.75 mmol/L indicating hypomagnesemia. Use of diabetes medication and indicators of poorer glucose control, insulin resistance, and obesity were associated with lower serum Mg in women, but not in men.

Conclusions

These results suggest that the higher incidence of diabetes in South Asians increases their risk for Mg deficiency and that health conditions that increase Mg requirements have a greater effect on Mg status in women than men.

Assessment of insulin sensitivity/resistance

Insulin resistance is one pretty troublesome entity which very commonly aggravates metabolic syndrome. Many methods and indices are available for the estimation of insulin resistance. It is essential to test and validate their reliability before they can be used as an investigation in patients. At present, hyperinsulinemic euglycemic clamp and intravenous glucose tolerance test are the most reliable methods available for estimating insulin resistance and are being used as a reference standard. Some simple methods, from which indices can be derived, have been validated e.g. homeostasis model assessment (HOMA), quantitative insulin sensitivity check index (QUICKI). For the clinical uses HOMA-insulin resistance, QUIKI, and Matsuda are suitable, while HES, McAuley, Belfiore, Cederholm, Avignon and Stumvoll index are suitable for epidemiological/research purposes. With increasing number of these available indices of IR, it may be difficult for clinicians to select the most appropriate index for their studies. This review provides guidelines that must be considered before performing such studies.

Correlation of insulin resistance by various methods with fasting insulin in obese

BACKGROUND

Several studies indicate that obesity is closely related to insulin resistance (IR). However, this relationship has not been adequately explored.

AIMS

This study aims to evaluate the prevalence of IR among obese using some indirect methods for assessment of IR.

MATERIALS AND METHODS

We analyzed the correlation of fasting insulin (FI) with body mass index. We examined 100 obese and overweight. Anthropometric measurements were done for all individuals. Blood lipids parameters, glucose, and insulin were assayed after a 10 h fast. The indices McAuley (McA), homeostasis model assessments (HOMA), quantitative insulin sensitivity check index (QUICKI) were used to assess IR.

RESULTS

In this study, the correlations of FI with McA, HOMA and QUICKI were significant (P < 0.05). FI test had significant sensitivity and specificity when compared with McA, HOMA and QUICKI indices. FI gives parallel results to the assessment of IR by other methods. Validity of FI was further analyzed by Cohen's kappa test and had a satisfactory agreement (χ =0.940).

CONCLUSION

Altogether, this study suggested that FI was sensitive and also specific as McA in assessment of IR in obese. Thus, FI can be used as an easy test to detect IR also in obese.

Irisin in patients with nonalcoholic fatty liver disease

OBJECTIVE

Irisin is a recently discovered myokine proposed to increase thermogenesis-related energy expenditure and improve metabolism. We aimed to comparatively evaluate serum irisin levels in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD) vs. controls and study their association with disease severity.

METHODS

Fifteen and 16 consecutively enrolled patients with biopsy-proven nonalcoholic simple steatosis (NAFL) and steatohepatitis (NASH), respectively, and 24 lean and 28 obese controls without NAFLD were recruited. Irisin, established adipokines and biochemical tests were measured.

RESULTS

Serum irisin levels were statistically different in obese controls (33.7±2.7 ng/mL; p<0.001) and patients with NAFL (30.5±1.5 ng/mL; p<0.001) and NASH (35.8±1.9 ng/mL; p=0.001) compared with lean controls (47.7±2.0 ng/mL), but were similar among patients with NAFL, NASH and obese controls. This difference remained significant after adjustment for body mass index (or waist circumference), gender, age, insulin resistance (assessed by HOMA-IR or QUICKI), exercise and time since blood collection. Serum leptin and adiponectin, but not irisin, levels were independently from BMI correlated with insulin resistance and cardiometabolic factors. Serum irisin tended to be higher in patients with (36.7±2.4 ng/mL) than without (30.8±1.2 ng/mL; p=0.02) portal inflammation and independently associated with the latter; these data need to be confirmed by future studies.

CONCLUSIONS

Serum irisin levels differ between lean controls and obese controls or NAFLD patients. Despite similar circulating irisin levels between NAFL and NASH groups, irisin may be independently and positively associated with the presence of portal inflammation. Future clinical and mechanistic studies are needed to confirm and extend these data.

Insulin resistance in euglycemic cirrhosis

BACKGROUND

Insulin resistance (IR) is associated with hepatic fibrosis and cirrhosis, regardless of its etiology but the mechanism of hyperinsulinemia in cirrhosis is still unclear. The current study was designed to assess hyperinsulinemia and pancreatic β-cell function in euglycemic cirrhosis of varied etiology.

METHODS

A cross sectional case control study of 100 subjects. IR was assessed by the Homeostasis Model Assessment (HOMA) and quantitative insulin sensitivity check index in euglycemic cirrhosis of varied etiology and in different stages of cirrhosis. HOMA-β was calculated for insulin secretion ability of pancreatic β-cells in different stages of cirrhosis.

RESULTS

Overall IR in euglycemic cirrhosis was seen in 68.5%. IR was seen in the order hepatitis C (100%), non-alcoholic fatty liver disease (100%), autoimmune hepatitis (100%), hepatocellular carcinoma (80%), alcoholic liver disease (72%) and hepatitis B (45%). HOMA-IR value was raised in Child Turcotte Pugh (CTP) score >9 (P value 0.0004) and model of end stage liver disease (MELD) score >15 (P value 0.02). HOMA-β was raised in CTP score >9 (P value 0.02) and MELD score >15 (P value 0.0003). HOMA-β level among diabetic controls was 27.1±7.7 compared to 154.6±80.7 in euglycemic cases (P value <0.0001).

CONCLUSION

IR is common in euglycemic cirrhosis and with advancement of liver disease; there is a compensatory increase in pancreatic β-cell insulin secretion to overcome the IR. However, over a period of time with fall in β-cell function development of hepatogenous diabetes may occur.

Salt loading exacerbates diastolic dysfunction and cardiac remodeling in young female Ren2 rats

OBJECTIVE

Recent data would suggest pre-menopausal insulin resistant women are more prone to diastolic dysfunction than men, yet it is unclear why. We and others have reported that transgenic (mRen2)27 (Ren2) rats overexpressing the murine renin transgene are insulin resistant due to oxidative stress in insulin sensitive tissues. As increased salt intake promotes inflammation and oxidative stress, we hypothesized that excess dietary salt would promote diastolic dysfunction in transgenic females under conditions of excess tissue Ang II and circulating aldosterone levels.

MATERIALS/METHODS

For this purpose we evaluated cardiac function in young female Ren2 rats or age-matched Sprague-Dawley (SD) littermates exposed to a high (4%) salt or normal rat chow intake for three weeks.

RESULTS

Compared to SD littermates, at 10weeks of age, female Ren2 rats fed normal chow showed elevations in left ventricular (LV) systolic pressures, LV and cardiomyocyte hypertrophy, and displayed reductions in LV initial filling rate accompanied by increases in 3-nitrotyrosine content as a marker of oxidant stress. Following 3weeks of a salt diet, female Ren2 rats exhibited no further changes in LV systolic pressure, insulin resistance, or markers of hypertrophy but exaggerated increases in type 1 collagen, 3-nitrotryosine content, and diastolic dysfunction. These findings occurred in parallel with ultrastructural findings of pericapillary fibrosis, increased LV remodeling, and mitochondrial biogenesis.

CONCLUSION

These data suggest that a diet high in salt in hypertensive female Ren2 rats promotes greater oxidative stress, maladaptive LV remodeling, fibrosis, and associated diastolic dysfunction without further changes in LV systolic pressure or hypertrophy.

Life-long endurance exercise in humans: circulating levels of inflammatory markers and leg muscle size

Human aging is associated with a loss of skeletal muscle and an increase in circulating inflammatory markers. It is unknown whether endurance training (Tr) can prevent these changes. Therefore we studied 15 old trained (O-Tr) healthy males and, for comparison, 12 old untrained (O-Un), 10 Young-Tr (Y-Tr) and 12 Young-Un (Y-Un). Quadriceps size, VO2 peak, CRP, IL-6, TNF-α and its receptors, suPAR, lipid profile, leucocytes and glucose homeostasis were measured. Tr was associated with an improved insulin profile (p<0.05), and lower leucocyte (p<0.05) and triglyceride levels (p<0.05), independent of age. Aging was associated with poorer glucose control (p<0.05), independent of training. The age-related changes in waist circumference, VO2 peak, cholesterol, LDL, leg muscle size, CRP and IL-6 were counteracted by physical activity (p<0.05). A significant increase in suPAR with age was observed (p<0.05). Most importantly, life-long endurance exercise was associated with a lower level of the inflammatory markers CRP and IL-6 (p<0.05), and with a greater thigh muscle area (p<0.05), compared to age-matched untrained counterparts. These findings in a limited group of individuals suggest that regular physical endurance activity may play a role in reducing some markers of systemic inflammation, even within the normal range, and in maintaining muscle mass with aging.

Modulation of liver function, antioxidant responses, insulin resistance and glucose transport by Oroxylum indicum stem bark in STZ induced diabetic rats

A decoction of stem bark of Oroxylum indicum Vent. (OI) is taken (2-3 times/day) by the tribal people of Sikkim, India to treat diabetes but scientific validation of its overall potential is lacking. Present study was aimed to assess in vitro antihyperglycemic activity of standardized OI extract using inhibition of α-glucosidase, BSA glycation and enhancement of insulin sensitivity. Antidiabetic and antioxidant modulatory effects of OI extract along with the blood biomarkers of toxic response were studied in streptozotocin (STZ) induced diabetic rats. In vitro analysis showed strong antioxidant capacity of OI -and potential to inhibit BSA glycation and α-glucosidase activity which was comparable to standard counterparts. Extract also improved insulin sensitivity in mature 3T3-L1 adipocytes. In vivo effects of OI extract (oral 250 mg/kg b.wt.) on STZ induced type II diabetic rats normalized the antioxidant status (p≤0.01). Analysis of blood biomarkers of toxic response indicated its safety. Lowering of total cholesterol and HDL levels (p≤0.05) and restoration of glycated Hb (p≤0.01) were also found in OI treated diabetic rats. HOMA-IR, QUICKI analysis along with area under the curve analysis showed the capacity of OI extract to enhance the insulin sensitivity significantly (p≤0.01) which was confirmed by increased GLUT-4 translocation in skeletal muscles.

Variants of NLRP3 gene are associated with insulin resistance in Chinese Han population with type-2 diabetes

AIMS

Nod like receptor pyrin domain containing 3 (NLRP3) is the best characterized member of nod like receptor family. Recent studies suggest that NLRP3 plays a crucial role in the pathogenesis of type-2 diabetes (T2DM), and variants in NLRP3 affect its mRNA stability and expression. Therefore, we hypothesize that the variants in NLRP3 gene may contribute to T2DM susceptibility. The aim of this study is to evaluate the association of NLRP3 SNPs with T2DM in Chinese Han patients.

METHODS

Two common variants in NLRP3 gene, rs10754558 and rs4612666, were detected using the polymerase chain reaction-restriction fragment length polymorphism procedure in 952 unrelated T2DM patients and 871 healthy controls. All participants were unrelated Chinese Hans.

RESULTS

The GG genotype and G allele frequencies of rs10754558 were significantly higher in T2DM patients than those in controls (for GG genotype, 19.6% vs. 14.5%, p=0.019; for G allele, 43.9% vs. 39.8%, p=0.013). The GG genotype of rs10754558 was significantly associated with higher LDL-C levels and more prone to insulin resistance, as evaluated by HOMA-IR or QUICK indexes.

CONCLUSIONS

The variant (rs10754558) in NLRP3 is related to insulin resistance and increased risk of T2DM in Chinese Han population.

The C57BL/6J Niemann-Pick C1 mouse model with decreased gene dosage has impaired glucose tolerance independent of body weight

The human Niemann-Pick C1 (NPC1) gene has been found to be associated with extreme (early-onset and morbid-adult) obesity and type 2 diabetes independent of body weight. We previously performed growth studies using BALB/cJ Npc1 normal (Npc1+/+) and Npc1 heterozygous (Npc1+/-) mice and determined that decreased Npc1 gene dosage interacts with a high-fat diet to promote weight gain and adiposity. The present study was performed using both BALB/cJ and C57BL/6J Npc1+/+ and Npc1+/- mice to determine if decreased Npc1 gene dosage predisposes to metabolic features associated with type 2 diabetes. The results indicated that C57BL/6J Npc1+/- mice, but not BALB/cJ Npc1+/- mice, have impaired glucose tolerance when fed a low-fat diet and independent of body weight. The results also suggest that an accumulation of liver free fatty acids and hepatic lipotoxicity marked by an elevation in the amount of plasma alanine aminotransferase (ALT) may be responsible for hepatic insulin resistance and impaired glucose tolerance. Finally, the peroxisome-proliferator activated receptor α (PPARα) and sterol regulatory element-binding protein-1 (SREBP-1) pathways known to have a central role in regulating free fatty acid metabolism were downregulated in the livers, but not in the adipose or muscle, of C57BL/6J Npc1+/- mice compared to C57BL/6J Npc1+/+ mice. Therefore, decreased Npc1 gene dosage among two different mouse strains interacts with undefined modifying genes to manifest disparate yet often related metabolic diseases.