Long-term Effects of Water-soluble Corn Bran Hemicellulose on Glucose Tolerance in Obese and Non-obese Patients: Improved Insulin Sensitivity and Glucose Metabolism in Obese Subjects

We examined the effect of soluble corn bran hemicellulose (CBH, 10g/day) on glucose control and serum insulin in three groups: patients with impaired glucose tolerance (IGT) with (20 subjects) or without (8 subjects) obesity and with healthy non-obese controls (10 subjects). Long-term supplementation (6 months) with CBH decreased the post oGTT curve for patients with impaired mild Type II diabetes, but not that for the controls. Hemoglobin A_1c decreased significantly during CBH supplementation in the obese patients, while the fasting glucose level decreased in all three groups, although not significantly. A decreased serum insulin response by oGTT was found in those patients with IGT.

The improved oGTT result was associated with improved insulin release and perhaps with peripheral insulin sensitivity. These findings suggest that CBH at a low dose might contribute to glycemic control and would play a useful role in treating Type II diabetes patients.     

Earlier Menarche Is Associated with Lower Insulin Sensitivity and Increased Adiposity in Young Adult Women

Objective

We aimed to assess whether age at menarche was associated with insulin sensitivity in young adult women.

Methods

We studied 54 healthy young women aged 20–30 years. Participants were grouped according to age at menarche: Early (≤11.0 years; n=13), Average (>12.0 and ≤13.0 years; n=28), and Late (≥14.0 years, n=13). Primary outcome was insulin sensitivity measured using intravenous glucose tolerance tests and Bergman’s minimal model. Body composition was assessed using whole-body dual-energy X-ray absorptiometry.

Results

Earlier menarche was associated with lower insulin sensitivity (p=0.015). There was also a continuous increase in adiposity with younger age at menarche, which was associated with increased weight (p=0.001), BMI (p=0.002), total body fat (p=0.049), and truncal fat (p=0.020). Stratified analyses showed that insulin sensitivity in Early women (5.5 x10^-4·min^-1(mU/l)) was lower than in Average (8.0 x10^-4·min^-1(mU/l), p=0.021) and Late (8.6 x10^-4·min^-1(mU/l), p=0.033) groups. Early women (weight=66.1 kg; BMI=24.1 kg/m²) were considerably heavier and fatter than Average (59.0 kg, p=0.004; 21.4 kg/m², p=0.002) and Late (57.0 kg, p=0.001; 20.8 kg/m², p=0.0009) women.

Conclusions

Early menarche is associated with lower insulin sensitivity and increased adiposity in young adulthood, potentially increasing the risk of type 2 diabetes and the metabolic syndrome later in life.     

Vertebral Bone Marrow Fat Is Positively Associated With Visceral Fat and Inversely Associated With IGF‐1 in Obese Women

Recent studies have demonstrated an important physiologic link between bone and fat. Bone and fat cells arise from the same mesenchymal precursor cell within bone marrow, capable of differentiation into adipocytes or osteoblasts. Increased BMI appears to protect against osteoporosis. However, recent studies have suggested detrimental effects of visceral fat on bone health. Increased visceral fat may also be associated with decreased growth hormone (GH) and insulin‐like growth factor 1 (IGF‐1) levels which are important for maintenance of bone homeostasis. The purpose of our study was to assess the relationship between vertebral bone marrow fat and trabecular bone mineral density (BMD), abdominal fat depots, GH and IGF‐1 in premenopausal women with obesity. We studied 47 premenopausal women of various BMI (range: 18–41 kg/m², mean 30 ± 7 kg/m²) who underwent vertebral bone marrow fat measurement with proton magnetic resonance spectroscopy (1H‐MRS), body composition, and trabecular BMD measurement with computed tomography (CT), and GH and IGF‐1 levels. Women with high visceral fat had higher bone marrow fat than women with low visceral fat. There was a positive correlation between bone marrow fat and visceral fat, independent of BMD. There was an inverse association between vertebral bone marrow fat and trabecular BMD. Vertebral bone marrow fat was also inversely associated with IGF‐1, independent of visceral fat. Our study showed that vertebral bone marrow fat is positively associated with visceral fat and inversely associated with IGF‐1 and BMD. This suggests that the detrimental effect of visceral fat on bone health may be mediated in part by IGF‐1 as an important regulator of the fat and bone lineage.     

Glucose Tolerance and Weight Loss in Obese Women with Obstructive Sleep Apnea

Background

The association of obstructive sleep apnea (OSA) with glucose intolerance and the beneficial effect of lifestyle intervention have been poorly investigated in women particularly before menopausal status. The study explored 1) whether OSA is associated with impaired glucose homeostasis in obese non diabetic premenopausal and menopausal women and 2) the effects of a 3- month lifestyle intervention on glucose homeostasis in OSA women.

Design and Methods

We consecutively recruited 98 obese women (39 premenopausal) from those referred for a weight loss intervention. Ambulatory nocturnal polysomnography, body composition, oral glucose tolerance test, insulin sensitivity and β cell function were assessed before and after intervention.

Results

41% of premenopausal and 64% of menopausal women had OSA which was associated with worse glucose homeostasis before menopausal status. Mean and minimal nocturnal oxygen saturation (SaO₂) was associated with neck/height ratio (NHR), independently of total and central obesity. Mean and minimal nocturnal SaO₂ and NHR were correlated with insulin sensitivity and fasting glucose. In multivariate analyses, nocturnal mean SaO₂ was negatively and independently correlated with fasting glucose (p<0.0001) and NHR with insulin sensitivity (p<0.0001). In OSA women, the intervention induced a 5% weight reduction and a significant increase in minimal nocturnal SaO₂, insulin sensitivity and β cell function. Changes in fasting glucose and insulin sensitivity were associated with those in minimal nocturnal SaO₂ (p<0.05) and not with weight loss.

Conclusions

In obese women, glucose homeostasis worsens due to nocturnal hypoxia and increased neck circumference through mechanisms partially independent of obesity. OSA is more clearly associated with glucose intolerance in premenopausal than in menopausal women. In OSA women, the improvement of nocturnal hypoxia induced by lifestyle modifications is associated with that of glucose homeostasis.     

Fat Distribution and Insulin Sensitivity in Postmenopausal Women: Influence of Hormone Replacement

Objective: To examine cross‐sectionally the influence of hormone replacement therapy (HRT) on the relationship between body composition and insulin sensitivity (Si). Research Methods and Procedures: Subjects were 57 early postmenopausal white women, 33 receiving HRT and 24 controls. Body composition was estimated using DXA and computed tomography scans at the abdomen and mid‐thigh. Si was assessed by a frequently sampled intravenous glucose tolerance test with minimal model analysis. Results: Compared with nonusers, HRT users had lower visceral adipose tissue, fasting serum glucose, and fasting insulin. Total body fat and unadjusted Si did not differ between groups. Visceral adipose tissue mass (VATM) was the only body‐fat compartment significantly associated with Si (r² = 0.43, p < 0.0001) in a model including total‐body fat, upper‐trunk fat, subcutaneous abdominal fat mass, leg fat, and mid‐thigh low‐density lean tissue. Lean body mass was positively correlated with Si among HRT users and tended to be negatively correlated among nonusers. HRT status also affected the relationship between VATM and Si such that, relative to nonusers, HRT users had lower Si across lower VATM levels, but higher Si across higher VATM. Discussion: These results suggest that in postmenopausal women, VATM is uniquely related to Si. HRT affects the relationship between VATM and Si and between lean body mass and Si. These interactions should be considered in future studies.     

血清网膜素-1 与绝经后女性冠心病的相关性

目的：网膜素是最近发现的脂肪因子,肥胖或2 型糖尿病（diabetes mellitus, DM）患者血清网膜素-1 较正常者明显降低。本 次研究主要为观察绝经后女性血清网膜素-1 水平与冠心病的相关性。方法：选取我院心内科住院有心绞痛症状,并行冠脉造影的 105 例绝经后女性患者。依据冠脉造影结果分为冠心病组(67 例)和对照组例（3）,常规收集临床资料,包括年龄、体重指数（body mass index, BMI）、吸烟史、高血压病史、糖尿病史及血液生化和血脂指标;酶联免疫吸附剂测定(enzyme linked immunosorbent assay, ELISA)法检测血清网膜素-1 浓度。结果：冠心病组血清网膜素-1 水平显著低于对照组（205.62± 73.31 vs 401.64± 146.79, P<0.001）。单因素logistic回归分析示吸烟、高血压病史、糖尿病史、高脂血症史、网膜素-1 水平降低是冠心病组的独立危险因素 (P<0.05)。多因素logistic 回归分析示血清网膜素-1 水平降低是冠心病组的独立危险因素(P<0.001)。结论：绝经后女性血清网膜素 -1 水平下降是冠心病的独立危险因素,可能可成为绝经后女性冠心病的预测指标。     

血清网膜素-1与绝经后女性冠心病的相关性

目的：网膜素是最近发现的脂肪因子,肥胖或2型糖尿病（diabetesmellitus,DM）患者血清网膜素-1较正常者明显降低。本次研究主要为观察绝经后女性血清网膜素-1水平与冠心病的相关性。方法：选取我院心内科住院有心绞痛症状,并行冠脉造影的105例绝经后女性患者。依据冠脉造影结果分为冠心病组（67例）和对照组例（3）,常规收集临床资料,包括年龄、体重指数（bodvmassindex,BMI）、吸烟史、高血压病史、糖尿病史及血液生化和血脂指标;酶联免疫吸附剂测定（enzymelinkedimmunosorbentassay,ELISA）法检测血清网膜素-1浓度。结果：冠心痛组血清网膜素-1水平显著低于对照组（205．62±73．31vs401．64±146．79．P〈0．001）。单因素logistic回归分析示吸烟、高血压痛史、糖尿病史、高脂血症史、网膜素-1水平降低是冠心病组的独立危险因素（P〈0．05）。多因素logistic回归分析示血清网膜素-1水平降低是冠心病组的独立危险因素（P〈0．001）。结论：绝经后女性血清网膜素-1水平下降是冠心痛的独立危险因素,可能可成为绝经后女性冠心病的预测指标。     

Visceral Fat Accumulation Is Associated with Colorectal Cancer in Postmenopausal Women

Background

Obesity is a known risk factor for colorectal cancer (CRC), and emerging data suggest that this association is mediated by visceral fat rather than total body fat. However, there is a lack of studies evaluating the association between visceral fat area and the prevalence of CRC.

Methods

To investigate the relationship between visceral adiposity and prevalence of CRC, data of 497 women diagnosed with CRC and 318 apparently healthy women were analysed and data of well-balanced 191 pairs of women with CRC and healthy women matched based on propensity scores were additionally analysed. Diagnosis of CRC was confirmed by colonoscopy and histology. Metabolic parameters were assessed, along with body composition, using computed tomography.

Results

The median visceral fat area was significantly higher in the CRC group compared with the control group before and after matching. The prevalence of CRC increased significantly with increasing visceral fat tertiles after matching (p for trend <0.01). A multivariate analysis showed that mean visceral fat area of individuals in the 67^th percentile or greater group was associated with an increased prevalence of CRC (adjusted odds ratio: 1.80; 95% confidence interval: 1.12–2.91 before matching and adjusted odds ratio: 2.96; 95% confidence interval: 1.38–6.33) compared with that of individuals in the 33^th percentile or lower group.

Conclusion

Thus, we conclude that visceral fat area is positively associated with the prevalence of CRC. Although we could not determine the causality, visceral adiposity may be associated with the risk of CRC. Further prospective studies are required to determine the benefits of controlling visceral obesity for reducing CRC risk.     

Rosiglitazone Improves Glucose Metabolism in Obese Adolescents With Impaired Glucose Tolerance: A Pilot Study

Impaired glucose tolerance (IGT) is a prediabetic state fueling the rising prevalence of type 2 diabetes mellitus (T2DM) in adolescents with marked obesity. Given the importance of insulin resistance, the poor β‐cell compensation and the altered fat partitioning as underlying defects associated with this condition, it is crucial to determine the extent to which these underlying abnormalities can be reversed in obese adolescents. We tested, in a pilot study, whether rosiglitazone (ROSI) restores normal glucose tolerance (NGT) in obese adolescents with IGT by improving insulin sensitivity and β‐cell function. In a small randomized, double‐blind, placebo (PLA)‐controlled study, lasting 4 months, 21 obese adolescents with IGT received either ROSI (8 mg daily) (n = 12, 5M/7F, BMI z‐score 2.44 ± 0.11) or PLA (n = 9, 4M/5F, BMI z‐score 2.41 ± 0.09). Before and after treatment, all subjects underwent oral glucose tolerance test (OGTT), hyperinsulinemic‐euglycemic clamp, magnetic resonance imaging, and ¹H NMR assessment. After ROSI treatment, 58% of the subjects converted to NGT compared to 44% in the PLA group (P = 0.528). Restoration of NGT was associated with a significant increase in insulin sensitivity (P < 0.04) and a doubling in the disposition index (DI) (P < 0.04), whereas in the PLA group, these changes were not significant. The short‐term use of ROSI appears to be safe in obese adolescents with IGT. ROSI restores NGT by increasing peripheral insulin sensitivity and β‐cell function, two principal pathophysiological abnormalities of IGT.     

TAZ Is a Negative Regulator of PPARγ Activity in Adipocytes and TAZ Deletion Improves Insulin Sensitivity and Glucose Tolerance

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Impact of Visceral Fat on Blood Pressure and Insulin Sensitivity in Hypertensive Obese Women

Objective: The relationship among body fat distribution, blood pressure, serum leptin levels, and insulin resistance was investigated in hypertensive obese women with central distribution of fat. Research Methods and Procedures: We studied 74 hypertensive women (age, 49.8 ± 7.5 years; body mass index, 39.1 ± 5.5 kg/m²; waist-to-hip ratio, 0.96 ± 0.08). All patients were submitted to 24-hour blood pressure ambulatory monitoring (24h-ABPM). Abdominal ultrasonography was used to estimate the amount of visceral fat (VF). Fasting blood samples were obtained for serum leptin and insulin determinations. Insulin resistance was estimated by homeostasis model assessment insulin resistance index (HOMA-r index). Results: Sixty-four percent of the women were postmenopausal, and all patients showed central distribution of fat (waist-to-hip ratio > 0.85). The VF correlated with systolic 24h-ABPM values (r = 0.28, p = 0.01) and with HOMA-r index (r = 0.27; p = 0.01). VF measurement (7.5 ± 2.3 vs. 5.9 ± 2.2 cm, p < 0.001) and the systolic 24h-ABPM (133 ± 14.5 vs. 126 ± 9.8 mm Hg, p = 0.04), but not HOMA-r index, were significantly higher in the postmenopausal group (n = 48) than in the premenopausal group (n = 26). No correlations were observed between blood pressure levels and HOMA-r index, leptin, or insulin levels. In the multiple regression analysis, visceral fat, but not age, body fat mass, or HOMA-r index, correlated with the 24h-ABPM (p = 0.003). Discussion: In centrally obese hypertensive women, the accumulation of VF, more often after menopause, is associated with higher levels of blood pressure and insulin resistance. The mechanism through which VF contributes to higher blood pressure levels seems to be independent of leptin or insulin levels.     

Infection with Soil-Transmitted Helminths Is Associated with Increased Insulin Sensitivity

Objective

Given that helminth infections have been shown to improve insulin sensitivity in animal studies, which may be explained by beneficial effects on energy balance or by a shift in the immune system to an anti-inflammatory profile, we investigated whether soil-transmitted helminth (STH)-infected subjects are more insulin sensitive than STH-uninfected subjects.

Design

We performed a cross-sectional study on Flores island, Indonesia, an area with high prevalence of STH infections.

Methods

From 646 adults, stool samples were screened for Trichuris trichiura by microscopy and for Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, and Strongyloides stercoralis by qPCR. No other helminth was found. We collected data on body mass index (BMI, kg/m²), waist-to-hip ratio (WHR), fasting blood glucose (FBG, mmol/L), insulin (pmol/L), high sensitive C-reactive protein (ng/ml) and Immunoglobulin E (IU/ml). The homeostatic model assessment for insulin resistance (HOMAIR) was calculated and regression models were used to assess the association between STH infection status and insulin resistance.

Results

424 (66%) participants had at least one STH infection. STH infected participants had lower BMI (23.2 vs 22.5 kg/m², p value = 0.03) and lower HOMAIR (0.97 vs 0.81, p value = 0.05). In an age-, sex- and BMI-adjusted model a significant association was seen between the number of infections and HOMAIR: for every additional infection with STH species, the HOMAIR decreased by 0.10 (p for linear trend 0.01). This effect was mainly accounted for by a decrease in insulin of 4.9 pmol/L for every infection (p for trend = 0.07).

Conclusion

STH infections are associated with a modest improvement of insulin sensitivity, which is not accounted for by STH effects on BMI alone.     

Weight Loss Is Associated With Increased Serum 25‐Hydroxyvitamin D in Overweight or Obese Women

Low circulating concentrations of vitamin D metabolites have been associated with increased risk for several diseases and clinical conditions. Large observational studies and surveys have shown that obesity is independently associated with lower serum 25‐hydroxyvitamin D (25(OH)D) concentration. Few studies have examined the effect of weight loss on serum 25(OH)D concentration. The purpose of this study was to prospectively examine the effect of weight loss on serum 25(OH)D concentration. Data were collected from 383 overweight or obese women who participated in a 2‐year clinical trial of a weight‐loss program, in which 51% (N = 195) lost at least 5% of baseline weight by 24 months, 18% (N = 67) lost 5–10%, and 33% (N = 128) lost >10%. Women who did not lose weight at 24 months had an increase in serum 25(OH)D of 1.9 (9.7) ng/ml (mean (SD)); 25(OH)D increased by 2.7 (9.1) ng/ml for those who lost 5–10% of baseline weight; and 25(OH)D increased by 5.0 (9.2) ng/ml for those who lost >10% of baseline weight (P = 0.014). At baseline, 51% (N = 197) of participants met or exceeded the recommended serum concentration of 20 ng/ml. By study end, 64% (N = 230) of overweight or obese women met this goal, as well as 83% (N = 20) of those whose weight loss achieved a normal BMI. These findings suggest that weight loss, presumably associated with a reduction in body fat, is associated with increased serum 25(OH)D concentration in overweight or obese women.     

Glucose Tolerance and Insulin Response in Atherosclerosis

Oral glucose tolerance tests were carried out on 51 men with atherosclerotic peripheral vascular disease, none of whom were known diabetics or had suffered recent myocardial infarction. The plasma insulin and blood sugar responses were compared with 47 age and sex-matched controls. There was no significant difference in obesity between the two groups. The patient group showed an increased plasma insulin response with a delay in return to fasting levels, and the blood sugar response was similar. These results suggest that hyperinsulinaemia and hyperglycaemia are often associated with atherosclerosis, and may have a role in its aetiology.     

Serum LBP Is Associated with Insulin Resistance in Women with PCOS

Introduction

Lipopolysaccharide-binding protein (LBP) is closely associated with many metabolic disorders. However, no study has been done to explore the relationship between LBP and polycystic ovary syndrome (PCOS). The objective of this study was to investigate whether the serum LBP level is elevated and associated with insulin resistance (IR) in PCOS.

Participants and Design

In this cross-sectional study, 117 PCOS patients and 121 age-matched controls were recruited. Hyperinsulinemic-euglycemic clamp was performed with an expression of M value for insulin sensitivity. Fasting serum samples were collected to detect LBP, lipids, insulin, sex hormones and high sensitive C reactive protein (hs-CRP). Pearson’s correlation and multiple linear regression was used to analyze the associations between M value and LBP level.

Settings

The study was performed in a clinical research center.

Results

Compared with controls, PCOS subjects had a significantly higher LBP concentration (33.03±14.59 vs. 24.35±10.31 μg/ml, p<0.001), and lower M value (8.21±3.06 vs. 12.31±1.72 mg/min/kg, p<0.001). Both in lean and overweight/obese individuals, serum LBP level was higher in PCOS subjects than that in controls. M value was negatively correlated with body mass index (BMI), fasting serum insulin, triglycerides, low-density lipoprotein cholesterol (LDL-c), free testosterone, high sensitive C reactive protein (hs-CRP) and LBP, whereas positively correlated with high-density lipoprotein cholesterol (HDL-c) and sex hormone binding globulin (SHBG). Serum LBP level was associated with M value after adjusting for BMI, fasting serum insulin, SHBG, as well as hs-CRP.

Conclusion

Serum LBP level significantly is elevated in PCOS, and is independently associated with IR in PCOS.     

Oxidative Stress in Severely Obese Persons Is Greater in Those With Insulin Resistance

The postprandial state seems to have a direct influence on oxidative status and insulin resistance. We determined the effect of an increase in plasma triglycerides after a high‐fat meal on oxidative stress in severely obese patients with differing degrees of insulin resistance. The study was undertaken in 60 severely obese persons who received a 60‐g fat overload with a commercial preparation. Measurements were made of insulin resistance, the plasma activity of various antioxidant enzymes, the total antioxidant capacity (TAC) and the plasma concentration of thiobarbituric acid reactive substances (TBARS). The patients with greater insulin resistance had a lower plasma superoxide dismutase (SOD) activity (P < 0.05) and a greater glutathione peroxidase (GSH‐Px) activity (P < 0.05). The high‐fat meal caused a significant reduction in SOD activity and an increase in the plasma concentration of TBARS in all the patients. Only the patients with lower insulin resistance experienced a significant increase in plasma catalase activity (2.22 ± 1.02 vs. 2.93 ± 1.22 nmol/min/ml, P < 0.01), remaining stable in the patients with greater insulin resistance. These latter patients had a reduction in plasma TAC (6.92 ± 1.93 vs. 6.29 ± 1.80 mmol/l, P < 0.01). In conclusion, our results show a close association between the degree of insulin resistance and markers of oxidative stress, both before and after a high‐fat meal. The postprandial state causes an important increase in oxidative stress, especially in severely obese persons with greater insulin resistance. However, we are unable to determine from this study whether there is first an increase in oxidative stress or in insulin resistance.     

Chromium Effects on Glucose Tolerance and Insulin Sensitivity in Persons at Risk for Diabetes Mellitus

ObjectiveTo investigate the effects of daily chromium picolinate supplementation on serum measures of glucose tolerance and insulin sensitivity in patients at high risk for type 2 diabetes mellitus.MethodsWe conducted a randomized, double-blind, placebo-controlled, modified cross-over clinical trial with 6-month sequences of intervention and placebo followed by a 6-month postintervention assessment. Adult patients with impaired fasting glucose, impaired glucose tolerance, or metabolic syndrome were enrolled. Participants received 6-month sequences of chromium picolinate or placebo at 1 of 2 dosages (500 or 1000 mcg daily). Primary outcome measures were change in fasting plasma glucose, 2-hour plasma glucose during oral glucose tolerance testing, fasting and 2-hour insulin, and homeostasis model assessment of insulin resistance (HOMA-IR). Secondary outcomes included anthropometric measures, blood pressure, endothelial function, hemoglobin A_1c, lipids, and urinary microalbumin.ResultsFifty-nine participants were enrolled. No changes were seen in glucose level, insulin level, or HOMA-IR (all P > .05) after 6 months of chromium at either dosage level (500 mcg or 1000 mcg daily) when compared with placebo. None of the secondary outcomes improved with either chromium dosage compared with placebo (P > .05).ConclusionsChromium supplementation does not appear to ameliorate insulin resistance or impaired glucose metabolism in patients at risk for type 2 diabetes and thus is unlikely to attenuate diabetes risk. (Endocr Pract. 2011;17:16-25)     

Insulin Sensitivity Determines the Effectiveness of Dietary Macronutrient Composition on Weight Loss in Obese Women

Objective: To determine whether macronutrient composition of a hypocaloric diet can enhance its effectiveness and whether insulin sensitivity (Si) affects the response to hypocaloric diets. Research Methods and Procedures: Obese nondiabetic insulin‐sensitive (fasting insulin < 10 μU/mL; n = 12) and obese nondiabetic insulin‐resistant (fasting insulin > 15 μU/mL; n = 9) women (23 to 53 years old) were randomized to either a high carbohydrate (CHO) (HC)/low fat (LF) (60% CHO, 20% fat) or low CHO (LC)/high fat (HF) (40% CHO, 40% fat) hypocaloric diet. Primary outcome measures after a 16‐week dietary intervention were: changes in body weight (BW), Si, resting metabolic rate, and fasting lipids. Results: Insulin‐sensitive women on the HC/LF diet lost 13.5 ± 1.2% (p < 0.001) of their initial BW, whereas those on the LC/HF diet lost 6.8 ± 1.2% (p < 0.001; p < 0.002 between the groups). In contrast, among the insulin‐resistant women, those on the LC/HF diet lost 13.4 ± 1.3% (p < 0.001) of their initial BW as compared with 8.5 ± 1.4% (p < 0.001) lost by those on the HC/LF diet (p < 0.04 between two groups). These differences could not be explained by changes in resting metabolic rate, activity, or intake. Overall, changes in Si were associated with the degree of weight loss (r = ?0.57, p < 0.05). Discussion: The state of Si determines the effectiveness of macronutrient composition of hypocaloric diets in obese women. For maximal benefit, the macronutrient composition of a hypocaloric diet may need to be adjusted to correspond to the state of Si.     

Effect of Oral Glucose Administration on Rebound Growth Hormone Release in Normal and Obese Women: The Role of Adiposity,Insulin Sensitivity and Ghrelin

Context

Metabolic substrates and nutritional status play a major role in growth hormone (GH) secretion. Uncovering the mechanisms involved in GH secretion following oral glucose (OG) administration in normal and obese patients is a pending issue.

Objective

The aim of this study was to investigate GH after OG in relation with adiposity, insulin secretion and action, and ghrelin secretion in obese and healthy women, to further elucidate the mechanism of GH secretion after OG and the altered GH secretion in obesity.

Participants and Methods

We included 64 healthy and obese women. After an overnight fast, 75 g of OG were administered; GH, glucose, insulin and ghrelin were obtained during 300 minutes. Insulin secretion and action indices and the area under the curve (AUC) were calculated for GH, glucose, insulin and ghrelin. Univariate and multivariate linear regression analyses were employed.

Results

The AUC of GH (μg/L•min) was lower in obese (249.8±41.8) than in healthy women (490.4±74.6), P=0.001. The AUC of total ghrelin (pg/mL•min) was lower in obese (240995.5±11094.2) than in healthy women (340797.5±37757.5), P=0.042. There were significant correlations between GH secretion and the different adiposity, insulin secretion and action, and ghrelin secretion indices. After multivariate analysis only ghrelin AUC remained a significant predictor for fasting and peak GH.