Insulin resistance, beta-cell function, and glucose tolerance in Brazilian adolescents with obesity or risk factors for type 2 diabetes mellitus

A study of ghrelin and leptin levels and their relationship to metabolic profiles in obese and lean Saudi women with polycystic ovary syndrome (PCOS)

BACKGROUND

Polycystic ovary syndrome (PCOS) is considered as one of the most frequently encountered hormonal pathologies in women during their reproductive years. Leptin and ghrelin, peptide hormones with adipostatic and orexigenic effect, respectively, seem to be involved in the metabolic changes that occur in PCOS. The aim of this study was to determine serum ghrelin and leptin levels in obese and lean Saudi women with PCOS and to investigate their relationship to the metabolic profiles in these women.

METHODS

This study was conducted as a prospective, observational, cross-sectional, case-control study, at the Department of Obstetrics and Gynecology, Al-Noor Hospital, Makkah, Kingdom of Saudi Arabia. The study population included 252 women [130 women with PCOS (diagnosed according to the Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus, 2003) and 122 normo-ovulatory women as matched controls] attending the outpatient Gynecology Clinic. Demographic details were recorded, blood was extracted following overnight fast and serum was used for the determination of serum ghrelin and leptin levels and other hormonal and biochemical parameters including total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, glucose, and insulin. Insulin resistance and sensitivity were calculated as HOMA-IR and HOMA-S.

RESULTS

No significant differences in ghrelin (P = 0.1830) and leptin (P = 0.8329) levels were detected between the PCOS and control groups. However, ghrelin levels were significantly lower; and leptin levels were significantly higher in obese PCOS patients in comparison with lean patients (P = 0.0001 for both). In the PCOS group, there were significant correlations between ghrelin and leptin levels with Body Mass Index (BMI), waist-hip ratio, total cholesterol, triglycerides, HDL, LDL and insulin levels. Multiple regression analysis demonstrated that insulin was the main determinant for ghrelin (R2 = 0.316) and leptin (R2 = 0.352) levels (P = 0.0001 for both).

CONCLUSIONS

Although serum ghrelin and leptin levels were found to be normal in women with PCOS; yet, there is a relationship, possibly linked to obesity, hyperinsulinemia and insulin resistance between these levels and metabolic profile of Saudi PCOS.

Lower body mass index is associated with a higher risk of giant cell arteritis: a systematic review and meta-analysis

OBJECTIVE

To characterize the possible association between body mass index (BMI) and risk of giant cell arteritis (GCA).

METHODS

We conducted a systematic review of observational studies (case-control or cohort study) that (I) reported BMI of patients with GCA prior to the diagnosis of GCA compared with subjects without GCA and (II) provided relative risk (RR), odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) from its regression analysis. Meta-analysis of the included studies was then performed to estimate the pooled effect using generic variance method of DerSimonian and Laird.

RESULTS

Three studies encompassing 141 patients with GCA and 85,736 controls met our eligibility criteria and were included in the data analyses. We demonstrated a statistically significant inverse relationship between BMI and risk of subsequent development of GCA as the risk increased by 8% when BMI was reduced by 1.0 kg/m(2) (pooled OR of 0.92/kg/m(2); 95% CI, 0.88-0.96).

CONCLUSIONS

Our study demonstrated a statistically significant inverse relationship between BMI and risk of subsequent development GCA. The pathophysiologic link behind this negative correlation is not well-characterized and further investigation is required.

Homeostatic model assessment indices in evaluation of insulin resistance and secretion in hemodialysis patients

Background

Some previous observations suggest that insulin resistance and glucose metabolism disturbances are frequent complications of chronic kidney disease. However, there are no conclusive studies on other indices of the effectiveness of insulin action in end-stage renal disease (ESRD) patients, including chronically hemodialysed (HD) ones.

Material/Methods

The groups comprised 33 non-diabetic ESRD hemodialysed patients and 33 healthy controls matched for age, sex, and body mass index (BMI). In both groups, HOMA-%B, HOMA-%S, HOMA-IR indices, and DI were calculated using HOMA1 and HOMA2 as measures of insulin resistance. The indices were also assessed in subgroups divided according to BMI.

Results

Mean fasting plasma glucose concentrations were lower in ESRD patients than in healthy persons (82.4±10.4 vs. 93.9±11.6, p=0.001). Fasting serum insulin concentrations were similar in both groups (median 6.8 vs. 6.0 mU/l, p=0.698). HOMA1-%B values were higher in ESRD patients than controls (median 137.1 vs. 81.6, p=0.002). HOMA1-%S (median 75.6 vs. 71.5) and HOMA1-IR (median 1.3 vs. 1.4) values were not significantly different (p=0.264 and p=0.189, respectively). DI1 levels were higher for HD patients than for healthy subjects (median 1.16 vs. 0.53, p<0.001). In subgroup analysis, all statistically significant differences were restricted mainly to persons with BMI <25 kg/m². Similar results as for the HOMA1 model were obtained for HOMA2.

Conclusions

1. HOMA beta-cell function is strongly correlated with HOMA insulin resistance in HD patients. 2. In non-diabetic ESRD hemodialysed patients, the HOMA indices and DI may be useful and important models in interpretation of glucose metabolism disturbances.

Impact of family history of diabetes on β-cell function and insulin resistance among Chinese with normal glucose tolerance

OBJECTIVE

This study investigated the impact of family history of diabetes (FHD) on β-cell function among Chinese with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

A multistage, stratified, cluster random sampling method was used to select a provincially representative sample from Fujian Province. Eventually, a total of 1,183 subjects were entered into the analysis. Several indexes were used to assess the function of β cells, including homeostasis model assessment (HOMA) of insulin resistance (IR), HOMA of β cells, insulinogenic index (IGI), and disposition index.

RESULTS

Overweight, increased body mass index, higher low-density lipoprotein cholesterol, and higher total cholesterol (TC) were the dominant features of positive FHD (FHD(+)). The FHD(+) subjects had lower insulin sensitivity (P<0.05). FHD(+) subjects showed higher risk of IR after adjusting for other risk factors (odds ratio 1.523 [1.272-2.009]). However, there was no significant difference in insulin secretion between the two groups. With the use of the multiple linear regression model, waist circumference (WC) and triglycerides (TGs) were found to be independent risk factors of the decline of insulin sensitivity in FHD(+) subjects, and insulin sensitivity declined significantly (P<0.05) with the increase of WC and TGs. In addition, the offspring of fathers with diabetes (PT2D) were much older and had higher TC than those of mothers with diabetes (MT2D). After adjusting for gender of the parents, there was no difference between MT2D and PT2D on insulin sensitivity.

CONCLUSIONS

Inheritance if diabetes is associated with the decline of insulin sensitivity. In addition, insulin sensitivity declined with increasing WC and TG in FHD(+) subjects.

Is acanthosis nigricans a reliable indicator for risk of type 2 diabetes in obese children and adolescents? A systematic review

Obesity and type 2 diabetes is becoming a major health problem affecting children and adolescents in the United States. This article reviews the current literature examining the association between the presence of acanthosis nigricans (AN) and risk for developing type 2 diabetes mellitus (T2DM) in obese children and adolescents. Ethnicity, family history of diabetes, and emergence of obesity are contributing factors for development of hyperinsulinemia, and insulin resistance, and ensuing visible changes on skin which is known as the AN. The purpose of this review was to assess the validity of AN as an early indicator of T2DM. Nineteen articles that were published from 1994 to 2010 were included for this review and reported an association between AN, hyperinsulinemia, and hyperglycemia. Nurses and advanced nurse practitioners working with children and adolescents have a tremendous role in identifying the risk factors, counseling, role modeling, and referring them to available community resources to promote healthy living. Early initiatives focusing on lifestyle changes may halt the progress, chronicity, and burden of T2DM in children and adolescents.

Study of beta-cell function (by HOMA model) in metabolic syndrome

INTRODUCTION

The clustering of cardiovascular risk factors is termed the metabolic syndrome (MS), which strongly predict risk of diabetes and cardiovascular disease. Many studies implicate insulin resistance (IR) in the development of diabetes, but ignore the contribution of beta-cell dysfunction. Hence, we studied beta-cell function, as assessed by HOMA model, in subjects with MS.

MATERIALS AND METHODS

We studied 50 subjects with MS diagnosed by IDF criteria and 24 healthy age- and sex-matched controls. Clinical evaluation included anthropometry, body fat analysis by bioimpedance, biochemical, and insulin measurement. IR and secretion were calculated by HOMA model.

RESULTS

Subjects with MS had more IR (HOMA-IR) than controls (3.35 ± 3.14 vs. 1.76 ± 0.53, P = 0.029) and secreted less insulin (HOMA-S) than controls (66.80 ± 69.66 vs. 144.27 ± 101.61, P = 0.0003), although plasma insulin levels were comparable in both groups (10.7 ± 10.2 vs. 8.2 ± 2.38, P = 0.44). HOMA-IR and HOMA-S were related with number of metabolic abnormalities. HOMA-IR was positively associated with body mass index, waist hip ratio, body fat mass, and percent body fat. HOMA-S was negatively associated with waist hip ratio, fasting plasma glucose and total cholesterol and positively with basal metabolic rate. Percent body fat was an independent predictor of HOMA-IR and waist hip ratio of HOMA-S in multiple regression analysis.

CONCLUSIONS

Subjects with MS have increased IR and decreased insulin secretion compared with healthy controls. Lifestyle measures have been shown to improve IR, insulin secretion, and various components and effects of MS. Hence, there is an urgent need for public health measures to prevent ongoing epidemic of diabetes and cardiovascular disease.

Gender-specific association of serum uric acid with metabolic syndrome and its components in juvenile obesity

BACKGROUND

Hyperuricemia has been implicated in the pathogenesis of obesity and related metabolic abnormalities. Studies on the association between serum uric acid (sUA) and metabolic syndrome (MetS) in juvenile obesity are scant. The effect of gender has not been evaluated.

METHODS

sUA (uricase method), anthropometric and biochemical indices were measured in gender-stratified children/adolescents consisting of 113 overweight/obese and 71 lean individuals.

RESULTS

In males, sUA was significantly elevated in overweight as well as obese patients. sUA was strongly associated with obesity indices and reflected sexual development, decreases in high density lipoprotein-cholesterol, and moderately, the number of MetS components. Waist circumference (WC) and Tanner stage explained 40% of sUA variability. Controlling for body mass index (BMI) and other MetS components, sUA was associated with abdominal obesity, explaining 30% of variability in WC. In females, sUA was significantly increased in obesity, high blood pressure (BP), and MetS and corresponded with the number of MetS components, indices of glucose metabolism, triglycerides (TG), and the atherogenecity index. Insulin-resistance (IR) (homeostasis model assessment; HOMA) and high BP explained 29% of sUA variability, whereas sUA, while controlling for BMI, age, and other MetS components, was associated with hypertriglyceridemia, hyperglycemia, high BP, and abdominal obesity. IR mediated the associations with high TG and glucose.

CONCLUSIONS

The association between sUA and MetS components in juvenile obesity is gender-specific, with females being related more closely and to more metabolic abnormalities. It may explain why, despite its lower concentrations, sUA is an independent predictor of mortality from all causes and from vascular diseases exclusively in females. Our findings may help in identifying metabolic abnormalities which may possibly be targeted by reducing sUA in males and females.

Hypermethylation of hepatic Gck promoter in ageing rats contributes to diabetogenic potential

AIMS/HYPOTHESIS

Hepatic glucokinase (GCK) is a key enzyme in glucose utilisation. Downregulation of its activity is associated with insulin resistance and type 2 diabetes mellitus. However, it is unknown whether hepatic Gck expression is influenced by age and is involved in ageing-mediated diabetes, and whether the degree of methylation of the hepatic Gck promoter is correlated with the transcription of Gck. To address the question, we evaluated hepatic Gck transcription and promoter methylation in young (14 weeks), adult (40 weeks) and aged (80 weeks) rats.

METHODS

Hepatic glycogen, Gck expression and the kinase activity of GCK were measured in three age groups. The CpG methylation status was determined by both bisulphite direct sequencing and clone sequencing of the PCR amplificates of Gck promoter. The causal relationship between Gck methylation and mRNA expression was confirmed by treating rat primary hepatocytes with 5-aza-2'-deoxycytidine (5-Aza-CdR).

RESULTS

We have shown an age-associated decline in hepatic glycogen, Gck expression levels and the kinase activity of hepatic GCK. The eleven CpG sites studied displayed age-related progressive methylation changes in hepatic Gck promoter, which were confirmed by two methods: direct and clone sequencing. After 5-Aza-CdR treatment of rat primary hepatocytes, there was a fourfold increase in Gck expression.

CONCLUSIONS/INTERPRETATION

Our results demonstrate that an age-related increase in methylation is negatively associated with hepatic Gck expression, suggesting that DNA methylation could be involved in increasing age-dependent susceptibility to hepatic insulin resistance and diabetes. Thus, the epigenetic modification of the hepatic Gck promoter may represent an important marker for diabetogenic potential during the ageing process.