Comparison between HOMA-IR and ISI-gly in detecting subjects with the metabolic syndrome

Metformin for early comorbid glucose dysregulation and schizophrenia spectrum disorders: a pilot double-blind randomized clinical trial

Patients with schizophrenia have exceedingly high rates of metabolic comorbidity including type 2 diabetes and lose 15-20 years of life due to cardiovascular diseases, with early accrual of cardiometabolic disease. In this study, thirty overweight or obese (Body Mass Index (BMI) > 25) participants under 40 years old with schizophrenia spectrum disorders and early comorbid prediabetes or type 2 diabetes receiving antipsychotic medications were randomized, in a double-blind fashion, to metformin 1500 mg/day or placebo (2:1 ratio; n = 21 metformin and n = 9 placebo) for 4 months. The primary outcome measures were improvements in glucose homeostasis (HbA1c, fasting glucose) and insulin resistance (Matsuda index-derived from oral glucose tolerance tests and homeostatic model of insulin resistance (HOMA-IR)). Secondary outcome measures included changes in weight, MRI measures of fat mass and distribution, symptom severity, cognition, and hippocampal volume. Twenty-two patients (n = 14 metformin; n = 8 placebo) completed the trial. The metformin group had a significant decrease over time in the HOMA-IR (p = 0.043) and fasting blood glucose (p = 0.007) vs. placebo. There were no differences between treatment groups in the Matsuda index, HbA1c, which could suggest liver-specific effects of metformin. There were no between group differences in other secondary outcome measures, while weight loss in the metformin arm correlated significantly with decreases in subcutaneous, but not visceral or hepatic adipose tissue. Our results show that metformin improved dysglycemia and insulin sensitivity, independent of weight loss, in a young population with prediabetes/diabetes and psychosis spectrum illness, that is at extremely high risk of early cardiovascular mortality. Trial Registration: This protocol was registered with clinicaltrials.gov (NCT02167620).

Changes in insulin sensitivity over time and associated factors in HIV-infected adolescents

OBJECTIVE

To compare prevalence of insulin resistance between perinatally HIV-infected (PHIV+) and perinatally HIV-exposed, but uninfected adolescents (PHEU), determine incidence of and contributory factors to new and resolved cases of insulin resistance in PHIV+, and evaluate glucose metabolism.

DESIGN

Cross-sectional design for comparison of prevalence among PHIV+ and PHEU. Longitudinal design for incidence and resolution of insulin resistance among PHIV+ at risk for these outcomes.

METHODS

The source population was adolescents from pediatric HIV clinics in the United States and Puerto Rico participating in the Pediatric HIV/AIDS Cohort Study, an ongoing prospective cohort study designed to evaluate impact of HIV infection and its treatment on multiple domains in preadolescents and adolescents. Insulin resistance was assessed by homeostatic model assessment of insulin resistance. Those with incident insulin resistance underwent 2-h oral glucose tolerance test and HbA1c. Baseline demographic, metabolic, and HIV-specific variables were evaluated for association with incident or resolved insulin resistance.

RESULTS

Unadjusted prevalence of insulin resistance in PHIV+ was 27.3 versus 34.1% in PHEU. After adjustment for Tanner stage, age, sex, and race/ethnicity, there was no significant difference between groups. Factors positively associated with developing insulin resistance included female sex, higher BMI z score, and higher waist circumference; those associated with resolving insulin resistance included male sex and lower BMI z score.

CONCLUSION

Prevalence of insulin resistance in PHIV+ and PHEU was substantially higher than that reported in HIV-uninfected nonoverweight youth, but similar to that in HIV-uninfected obese youth. Factors associated with incident or resolved insulin resistance among PHIV+ were similar to those reported in HIV-negative obese youth. However, a contributory role of HIV infection and/or its treatment to the incident risk of insulin resistance cannot be excluded.

Metabolic Syndrome and Hypertension Resulting from Fructose Enriched Diet in Wistar Rats

Increased sugar consumption, especially fructose, is strongly related to the development of type 2 diabetes (T2D) and metabolic syndrome. The aim of this study was to evaluate long term effects of fructose supplementation on Wistar rats. Three-week-old male rats were randomly divided into 2 groups: control (C; n = 14) and fructose fed (FF; n = 18), with a fructose enriched drink (20-25% w/v fructose in water) for 21 weeks. Systolic blood pressure, fasting glycemia, and bodyweight were regularly measured. Glucose tolerance was evaluated three times using an oral glucose tolerance test. Insulin levels were measured concomitantly and insulin resistance markers were evaluated (HOMA 2-IR, Insulin Sensitivity Index for glycemia (ISI-gly)). Lipids profile was evaluated on plasma. This fructose supplementation resulted in the early induction of hypertension without renal failure (stable theoretical creatinine clearance) and in the progressive development of fasting hyperglycemia and insulin resistance (higher HOMA 2-IR, lower ISI-gly) without modification of glucose tolerance. FF rats presented dyslipidemia (higher plasma triglycerides) and early sign of liver malfunction (higher liver weight). Although abdominal fat weight was increased in FF rats, no significant overweight was found. In Wistar rats, 21 weeks of fructose supplementation induced a metabolic syndrome (hypertension, insulin resistance, and dyslipidemia) but not T2D.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Progressive Induction of Type 2 Diabetes: Effects of a Reality-Like Fructose Enriched Diet in Young Wistar Rats

Purpose

The aim of this study was to characterize short and medium-lasting effects of fructose supplementation on young Wistar rats. The diet was similar to actual human consumption.

Methods

Three week old male rats were randomly divided into 2 groups: control (C; n = 16), fructose fed (FF; n = 16) with a fructose enriched drink for 6 or 12 weeks. Bodyweight, fasting glycemia and systolic blood pressure were monitored. Glucose tolerance was evaluated using an oral glucose tolerance test. Insulinemia was measured concomitantly and enable us to calculate insulin resistance markers (HOMA-IR, Insulin Sensitivity Index for glycemia: ISI-gly). Blood chemistry analyses were performed.

Results

After six weeks of fructose supplementation, rats were not overweight but presented increased fasting glycemia, reduced glucose tolerance, and lower insulin sensitivity compared to control group. Systolic blood pressure and heart weight were also increased without any change in renal function (theoretical creatinine clearance). After twelve weeks of fructose supplementation, FF rats had increased bodyweight and presented insulin resistance (higher HOMA-IR, lower ISI-gly). Rats also presented higher heart volume and lower ASAT/ALAT ratio (presumed liver lesion). Surprisingly, the Total Cholesterol/Triglycerides ratio was increased only after six weeks of fructose supplementation, predicting a higher LDL presence and thus a higher risk of developing cardiovascular disease. This risk was no longer present after twelve weeks of a fructose enriched diet.

Conclusion

On young Wistar rats, six weeks of fructose supplementation is sufficient to induce signs of metabolic syndrome. After twelve weeks of fructose enriched diet, rats are insulin resistant. This model enabled us to study longitudinally the early development of type 2 diabetes.

Relationship between serum concentrations of persistent organic pollutants and markers of insulin resistance in a cohort of women with a history of gestational diabetes mellitus

The aim of the present study was to assess the relationship between serum concentrations of several persistent organic pollutants and insulin resistance markers in a cohort of women with a history of gestational diabetes mellitus. ∑POPs was computed as the sum of individual serum POP concentrations. No statistically significant associations were found between levels of any POP and fasting glucose. However, polychlorinated biphenyl (PCB) congeners 138 and 180 were positively associated with 2-h glucose levels and PCB 180 also with fasting immunoreactive insulin (IRI). We also found a positive association of p,p'- dichlorodiphenyldichloroethylene (p,p'- DDE), PCBs (138, 153, and 180), hexachlorobenzene, and ∑POPs with 2-h IRI. Serum concentrations of PCBs (138, 153, and 180), hexachlorobenzene, and ∑POPs were also positively associated with homeostasis model assessment (HOMA2-IR) levels. Moreover, p,p'- DDE, PCBs (138, 153 and 180), hexachlorobenzene, and ∑POPs were negatively associated with Insulin Sensitivity Index (ISI-gly) levels. No significant association was found between glycated hemoglobin and the concentrations of any POP. The removal of women under blood glucose lowering treatment from the models strengthened most of the associations previously found for the whole population. Our findings suggest that exposure to certain POPs is a modifiable risk factor contributing to insulin resistance.

ZHENG May Contribute to Obesity Phenotypes Based on Body Composition: A Pilot Study on the Traditional Chinese Medicine Approach

Objective. Obesity therapy needs new approaches to complement current phenotyping systems. This study aims to assess associations between the Traditional Chinese Medicine (TCM) ZHENG and obesity phenotypes. Methods. We assessed medical history and habitual physical activity and measured body composition, fasting plasma glucose and insulin, and lipids. We collected TCM data through face-to-face interview. ZHENG elements (essentials and locations) were identified by TCM practitioner. Primary ZHENG was assessed by cluster analysis. Results. In 140 consecutive subjects enrolled in a university clinic (body mass index (BMI): 39.9 ± 5.8 kg/m2), ZHENG essentials were identified as “QiXu,” “Re,” “YinXu,” and “TanShi” (totally 86.8%). Locations were “Shen,” “Wei,” “Pi,” and “Gan” (totally 91.8%). Four types of primary ZHENG were identified: A (37.1% of subjects), B (16.5%), C (35.7%), and D (10.7%). Subjects in type D showed elevated BMI, total fat mass (FM), FM index, trunk FM, and less physical activity, as compared with others. Subjects in type B changed regional body composition (reduced trunk FM% and elevated appendicular FM%). Biological parameters did not differ across primary ZHENG clusters. Conclusions. Obesity phenotypes based on body composition differ according to ZHENG in obese patients. This study is a first step toward understanding the contribution of TCM to obesity phenotyping.

Contribution of 24 obesity-associated genetic variants to insulin resistance, pancreatic beta-cell function and type 2 diabetes risk in the French population

CONTEXT

Obesity is the major determinant of type 2 diabetes (T2D), presumably through its effect on insulin resistance. Genome-wide association studies reported many single-nucleotide polymorphisms (SNPs) that increase obesity risk and body mass index (BMI), but their impact on T2D-related traits and risk is unclear.

OBJECTIVE

We aimed at analyzing the effect of 24 obesity risk alleles, separately and in combination, on variation of both insulin resistance and β-cell dysfunction, and on T2D risk.

DESIGN

We genotyped 24 obesity-associated SNPs and calculated an obesity genotype score (sum of the obesity risk alleles per individual). We analyzed the contribution of each SNP and this score to the variation of four metabolic indices: homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of the pancreatic β-cell function (HOMA-B), insulin sensitivity index (ISI) and insulinogenic index (II) (in up to 8050 nondiabetic French individuals) and to T2D risk (in 2077 T2D cases and 3085 controls).

RESULTS

We found a highly significant effect of the obesity genotype score on increased insulin resistance adjusted for age and gender (β=0.02; P-value=7.16 × 10(-9) for HOMA-IR). Individually, we identified nominal or significant association between increased insulin resistance and risk alleles in FAIM2, FTO, GNPDA2, MC4R, NPC1, PTER and SH2B1. Most signals, including the obesity genotype score and FTO SNP, were also associated with increased β-cell function (β=0.01; P-value=1.05 × 10(-6) and β=0.04; P-value=3.45 × 10(-4), respectively). In our T2D case-control study, only the obesity genotype score and the well-known FTO locus significantly contributed to T2D risk (OR=1.03; P-value=9.99 × 10(-3) and OR=1.15; P-value=9.46 × 10(-4), respectively). Adjustment for BMI abolished all significant associations.

CONCLUSIONS

Genetic predisposition to obesity contributes to increased insulin resistance and to its compensation through increased β-cell function, and weakly increases the T2D risk. These associations are mediated by BMI.

Sex differences in lipid profiles in relation to the progression of glucose abnormalities

BACKGROUND

In the present study, we investigated the role of changes in blood lipids in the abolition of the lower cardiovascular risk associated with the female gender in individuals with type 2 diabetes mellitus (T2DM).

METHODS

An oral glucose tolerance test (OGTT) was performed in 1091 consecutive patients (478 men and 613 women) and patients were divided into groups as follows: (i) those with normal glucose tolerance (NGT; n = 589); (ii) those with pre-diabetes (pre-T2DM), who were further divided into those with impaired fasting glucose (IFG; n = 212), impaired glucose tolerance (IGT; n = 84), and both IFG and IGT (IFG/IGT; n = 102); and (iii) those with T2DM (n = 104). Total cholesterol, triglycerides, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), apolipoprotein (apo) A-I, apoB, and the apoB:apoA-I ratio were determined in each patient. Differences in lipids between the different groups were assessed using Student's t-test.

RESULTS

Significantly higher triglyceride levels and an apoB:apoA-I ratio were found in NGT men (P < 0.0001), along with lower HDL-C and apoA-I (P < 0.0001). Men in the pre-T2DM group maintained a higher apoB:apoA-I ratio (P < 0.05) and lower HDL-C (P < 0.0001) compared with women. In the T2DM group, only HDL-C was lower in men compared with women (P < 0.05).

CONCLUSIONS

The progression of glucose intolerance from NGT to pre-T2DM and T2DM exhibits striking sex differences regarding the lipid profile. The data demonstrate a worsening of plasma lipid composition in women who become diabetic. This could explain, at least in part, the loss of the more favorable cardiovascular risk normally associated with NGT women.

Selection of the appropriate method for the assessment of insulin resistance

Insulin resistance is one of the major aggravating factors for metabolic syndrome. There are many methods available for estimation of insulin resistance which range from complex techniques down to simple indices. For all methods of assessing insulin resistance it is essential that their validity and reliability is established before using them as investigations. The reference techniques of hyperinsulinaemic euglycaemic clamp and its alternative the frequently sampled intravenous glucose tolerance test are the most reliable methods available for estimating insulin resistance. However, many simple methods, from which indices can be derived, have been assessed and validated e.g. homeostasis model assessment (HOMA), quantitative insulin sensitivity check index (QUICKI). Given the increasing number of simple indices of IR it may be difficult for clinicians and researchers to select the most appropriate index for their studies. This review therefore provides guidelines and advices which must be considered before proceeding with a study.

Flavonoid-rich cocoa consumption affects multiple cardiovascular risk factors in a meta-analysis of short-term studies

A growing body of evidence suggests that the consumption of foods rich in polyphenolic compounds, particularly cocoa, may have cardioprotective effects. No review, however, has yet examined the effect of flavonoid-rich cocoa (FRC) on all major cardiovascular risk factors or has examined potential dose-response relationships for these effects. A systematic review and meta-analysis of randomized, controlled trials was performed to evaluate the effect of FRC on cardiovascular risk factors and to assess a dose-response relationship. Inclusion and exclusion criteria as well as dependent and independent variables were determined a priori. Data were collected for: blood pressure, pulse, total cholesterol, HDL cholesterol, LDL cholesterol, TG, BMI, C-reactive protein, flow-mediated vascular dilation (FMD), fasting glucose, fasting insulin, serum isoprostane, and insulin sensitivity/resistance indices. Twenty-four papers, with 1106 participants, met the criteria for final analysis. In response to FRC consumption, systolic blood pressure decreased by 1.63 mm Hg (P = 0.033), LDL cholesterol decreased by 0.077 mmol/L (P = 0.038), and HDL cholesterol increased by 0.046 mmol/L (P = 0.037), whereas total cholesterol, TG, and C-reactive protein remained the same. Moreover, insulin resistance decreased (HOMA-IR: -0.94 points; P < 0.001), whereas FMD increased (1.53%; P < 0.001). A nonlinear dose-response relationship was found between FRC and FMD (P = 0.004), with maximum effect observed at a flavonoid dose of 500 mg/d; a similar relationship may exist with HDL cholesterol levels (P = 0.06). FRC consumption significantly improves blood pressure, insulin resistance, lipid profiles, and FMD. These short-term benefits warrant larger long-term investigations into the cardioprotective role of FRC.

Serum insulin-like growth factor binding protein-1: an improvement over other simple indices of insulin sensitivity in the assessment of subjects with normal glucose tolerance

Background

Insulin resistance is associated with an increased risk of cardiovascular disease and diabetes. It can be assessed using complex reference techniques, such as clamp or frequently sampled intravenous glucose tolerance test (FSIVGTT). Therefore, simple indices derived from fasting insulin and glucose concentrations have been proposed. The aim of this study is to assess fasting serum insulin-like growth factor binding protein-1 (IGFBP-1) as a simple index of insulin sensitivity compared with other simple indices and FSIVGTT.

Methods

Fasting serum IGFBP-1, fasting plasma insulin (FPI), homeostasis model assessment (HOMA-IR), quantitative insulin check index (QUICKI), fasting glucose to insulin ratio (FGIR), Raynaud and insulin glycaemic index (ISI-gly) were correlated with FSIVGTT (Si) in 22 subjects with normal glucose tolerance (NGT) and nine with impaired fasting glucose (IFG).

Results

In NGT individuals, IGFBP-1 correlated more strongly with Si than did any other index both before ( r = 0.76) and after ( r = 0.79) natural logarithm (ln) transformation. In subjects with IFG, IGFBP-1 was weakly correlated with Si before and after ln-transformation ( r = 0.55, r = 0.56, respectively), but ISI-gly was the index most strongly correlated with Si ( r = 0.77, r = 0.85, respectively).

Conclusions

In subjects with NGT, fasting serum IGFBP-1 could be used as a simple reliable marker of insulin sensitivity. For more accurate estimation of insulin sensitivity in normal subjects and those with IFG, ln-transformation is preferred over raw data.

Metabolic profile in sons of women with polycystic ovary syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder with strong familial aggregation. It has been demonstrated that parents and brothers of PCOS women exhibit insulin resistance and related metabolic defects. However, metabolic phenotypes in sons of PCOS women have not been described.

OBJECTIVE

Our objective was to assess the metabolic profiles in sons of women with PCOS during different stages of life: early infancy, childhood, and adulthood.

DESIGN

Eighty sons of women with PCOS (PCOS(S)) and 56 sons of control women without hyperandrogenism (C(S)), matched for age, were studied. In early infancy, glucose and insulin were determined in the basal sample. In children and adults, a 2-h oral glucose tolerance test was performed with measurements of glucose and insulin. Adiponectin, leptin, C-reactive protein, SHBG, and serum lipids were determined in the basal sample during the three periods.

RESULTS

During early infancy, PCOS(S) showed higher weight (P = 0.038) and weight sd score (P = 0.031) than C(S). During childhood, weight (P = 0.003), body mass index (BMI) (P < 0.001), BMI sd score (P < 0.001), waist circumference (P = 0.001), total cholesterol (P = 0.007), and low-density lipoprotein cholesterol (P = 0.022) were higher in PCOS(S) compared with C(S), but after adjusting for BMI, these differences were nonsignificant. During adulthood, PCOS(S) exhibited higher weight (P = 0.022), BMI (P = 0.046), and waist circumference (P = 0.028) than C(S). Fasting insulin (P = 0.030), homeostasis model assessment for insulin resistance (P = 0.034), total cholesterol (P = 0.043), low-density lipoprotein cholesterol (P = 0.034), and 2-h insulin (P = 0.006) were also significantly higher and insulin sensitivity index composite significantly lower in PCOS(S) than in C(S) (P = 0.003). After adjusting for BMI, only 2-h insulin and insulin sensitivity index composite remained significantly different.

CONCLUSIONS

This study indicates that sons of PCOS women exhibit higher body weight from early infancy. In addition, insulin resistance became evident as the subjects got older, which may place them at risk for the development of type 2 diabetes and cardiovascular disease.