Sleep processes exert a predominant influence on the 24-h profile of heart rate variability

Adverse cardiovascular events are known to exhibit 24-h variations with a peak incidence in the morning hours and a nonuniform distribution during the night. The authors examined whether these 24-h variations could be related to circadian or sleep-related changes in heart rate (HR) and in HR variability (HRV). To differentiate the effect of circadian and sleep-related influences, independent of posture and of meal ingestion, seven normal subjects were studied over 24 h, once with nocturnal sleep from 2300 to 0700 h and once after a night of sleep deprivation followed by 8 h of daytime sleep from 0700 to 1500 h. The subjects were submitted to constant conditions (continuous enteral nutrition and bed rest). HRV was calculated every 5 min using two indexes: the standard deviation of normal R-R intervals (SDNN) and the ratio of low-frequency to low-frequency plus high-frequency power. Sleep processes exerted a predominant influence on the 24-h profiles of HR and HRV, with lowest HRV levels during slow wave sleep, high levels during REM sleep and intrasleep awakenings, and abrupt increases in HR at each transition from deeper sleep to lighter sleep or awakenings. The circadian influence was smaller, except for SDNN, which displayed a nocturnal increase of 140% whether the subjects slept or not. This study demonstrates that 24-h variations in HR and HRV are little influenced by the circadian clock andare mainly sleep-stage dependent. The results suggest an important role for exogenous factors in the morning increase in cardiovascular events. During sleep, the sudden rises in HR at each transition from deeper sleep to lighter sleep or awakenings might precipitate the adverse cardiac events.     

Acute effects of stretching exercise on the heart rate variability in subjects with low flexibility levels

The study investigated the heart rate (HR) and heart rate variability (HRV) before, during, and after stretching exercises performed by subjects with low flexibility levels. Ten men (age: 23 ± 2 years; weight: 82 ± 13 kg; height: 177 ± 5 cm; sit-and-reach: 23 ± 4 cm) had the HR and HRV assessed during 30 minutes at rest, during 3 stretching exercises for the trunk and hamstrings (3 sets of 30 seconds at maximum range of motion), and after 30 minutes postexercise. The HRV was analyzed in the time ('SD of normal NN intervals' [SDNN], 'root mean of the squared sum of successive differences' [RMSSD], 'number of pairs of adjacent RR intervals differing by >50 milliseconds divided by the total of all RR intervals' [PNN50]) and frequency domains ('low-frequency component' [LF], 'high-frequency component' [HF], LF/HF ratio). The HR and SDNN increased during exercise (p < 0.03) and decreased in the postexercise period (p = 0.02). The RMSSD decreased during stretching (p = 0.03) and increased along recovery (p = 0.03). At the end of recovery, HR was lower (p = 0.01), SDNN was higher (p = 0.02), and PNN50 was similar (p = 0.42) to pre-exercise values. The LF increased (p = 0.02) and HF decreased (p = 0.01) while stretching, but after recovery, their values were similar to pre-exercise (p = 0.09 and p = 0.3, respectively). The LF/HF ratio increased during exercise (p = 0.02) and declined during recovery (p = 0.02), albeit remaining higher than at rest (p = 0.03). In conclusion, the parasympathetic activity rapidly increased after stretching, whereas the sympathetic activity increased during exercise and had a slower postexercise reduction. Stretching sessions including multiple exercises and sets acutely changed the sympathovagal balance in subjects with low flexibility, especially enhancing the postexercise vagal modulation.     

Circadian and ultradian rhythms in heart rate variability.

AIM: Heart rate variability (HRV) patterns reflect the changing effect of sympathetic and parasympathetic modulation of the autonomic nervous system. While overall and circadian heart rate (HR) and HRV are well characterized by traditional measures, there is currently no method to measure ultradian cycles of HR and HRV. MATERIALS AND METHODS: HR/HRV for each 2-min interval was calculated using normal-to-normal interbeat intervals from overnight polysomnographic ECGs in 113 subjects, aged 58+/-10 years (65 male, 48 female). HR, SDNN2, high-frequency power (HF) and the LF (low-frequency power)/HF ratio were plotted. A curve-fitting algorithm, developed in MatLab, identified cyclic patterns of HR/HRV and extracted parameters to characterize them. Results were compared for older vs. younger patients, males vs. females, with vs. without severe sleep apnea, and for the upper and lower half of sleep efficiency. RESULTS: Ultradian patterns for different HR/HRV indices had variable correspondences with each other and none could be considered surrogates. Differences were seen for all comparison groups, but no one marker was consistently different across comparisons. CONCLUSION: Each HR/HRV parameter has its own rhythm, and the correspondence between these rhythms varies greatly across subjects. Quantification of ultradian patterns of HRV is feasible and could provide new insights into autonomic physiology.     

2型糖尿病内脏脂肪含量与胰岛β细胞功能及胰岛素抵抗的关系研究

目的:研究2型糖尿病患者内脏脂肪含量与胰岛β细胞功能及胰岛素抵抗的关系。方法:对65例初诊2型糖尿病患者采用256 CT平脐经L4、5水平进行扫描并测量皮下及内脏脂肪含量,并以BMI不同进行分组,即体重正常组、超重组、肥胖组。采用稳态模式评估法(HOMA)计算胰岛素抵抗指数、胰岛B细胞分泌功能,测量入组患者的相关人体指标、空腹血生化检查指标。结果:超体重组、肥胖组患者腰围、体重指数(body mass index, BMI)、甘油三酯(triglyceride, TG)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol, LDL-C)、空腹血糖,(fasting blood-glucose, FBG)、空腹胰岛素(fasting insulin, FINS)INS、稳态模型胰岛素抵抗指数(Homeostatic Model Assessment for Insulin Resistance, HOMA-IR)、胰岛β细胞功能指数(Homeostasis model assessment-β,HOMA-β)指标肥胖组、超重组均明显高于正常体重组(P0.05),超体重组、肥胖组内脏脂肪含量、内脏脂肪面积、皮下脂肪含量、脂肪总含量、脂肪百分比,超重组、肥胖组均明显高于正常体重组(P0.05),且肥胖组各项指标明显高于超重组(P0.05)。多元回归分析显示腹部脂肪总含量、内脏脂肪含量、皮下脂肪含量、内脏脂肪面积、BMI与胰岛素抵抗呈正相关,而其中内脏脂肪含量及面积关系最密切。结论:内脏脂肪含量是2型糖尿病胰岛素抵抗及B细胞功能变化的独立影响因素。     

Dependency of the metabolic effect of sc-injected human regular insulin on intra-abdominal fat in patients with type 2 diabetes.

Ten patients with type 2 diabetes were enrolled in an isoglycemic glucose clamp study to determine the impact of intra-abdominal fat, subcutaneous abdominal fat and total abdominal fat on the metabolic effect of a single bolus (0.2 IU/kg) of sc-injected human regular insulin. The maximum metabolic effect associated highly and negatively with intra-abdominal fat (r = - 0.72, p < 0.02) and with the homeostasis model assessment insulin resistance score (HOMA, r = - 0.71, p < 0.03). Likewise, the total metabolic effect of sc-injected insulin correlated strongly and negatively with intra-abdominal fat (r = - 0.77, p < 0.01), HOMA (r = - 0.74, p < 0.02) and HbA (1c) (r = - 0.70, p < 0.03). Stepwise multiple regression analyses showed that the highest metabolic effect was only significantly predicted by intra-abdominal fat, indicating a high negative correlation with the maximum effect (beta = - 0.72) whereas time to maximum metabolic effect showed a strong (beta = 0.72) and positive correlation with HOMA. In combination with the HOMA, it is intra-abdominal fat, and not subcutaneous abdominal fat, which explains 50 - 75 % of the variability of the effect of sc human regular insulin in patients with type 2 diabetes.     

Fatness, fitness, and insulin sensitivity among 7- to 9-year-old children

Objective: The purpose of this study was to examine the relationships among fatness and aerobic fitness on indices of insulin resistance and sensitivity in children. Research Design and Methods: A total of 375 children (193 girls and 182 boys) 7 to 9 years of age were categorized by weight as normal‐weight, overweight, or obese and by aerobic fitness based on a submaximal physical working capacity test (PWC). Fasting blood glucose (GLU) and insulin (INS) were used to calculate various indices of insulin sensitivity (GLU/INS), the homeostasis model assessment (HOMA), and the quantitative insulin sensitivity check index (QUICKI). Surrogate measures of pancreatic β cell function included the insulinogenic index (INS/GLU) and the HOMA estimate of pancreatic β‐cell function (HOMA %B). Results: Insulin sensitivity and secretion variables were significantly different between the normal‐weight children and the overweight and obese subjects. Fasting insulin (FI), HOMA, QUICKI, and INS/GLU were significantly different between the overweight and obese subjects. Likewise, the high fitness group possessed a better insulin sensitivity profile. In general, the normal‐weight–high fit group possessed the best insulin sensitivity profile and the obese‐unfit group possessed the worst insulin sensitivity profile. Several significant differences existed among the six fat‐fit groups. Of particular note are the differences within BMI groups by fitness level and the comparison of values between the normal‐weight–unfit subjects and the overweight and obese subjects with high fitness. Conclusions: The results indicate that aerobic fitness attenuates the difference in insulin sensitivity within BMI categories, thus emphasizing the role of fitness even among overweight and obese children.     

Exercise and diet induced weight loss improves measures of oxidative stress and insulin sensitivity in adults with characteristics of the metabolic syndrome

Obesity and insulin resistance (IR) increase the risk for coronary heart disease; however, much of this risk is not attributable to traditional risk factors. We sought to determine whether weight loss associated with supervised aerobic exercise beneficially alters biomarkers of oxidative stress and whether these alterations are associated with improvements in measures of insulin resistance. Twenty-five sedentary and overweight to obese [body mass index (BMI) = 33.0 +/- 0.8 kg/m(2)] individuals, with characteristics of the metabolic syndrome, participated in a 4- to 7-mo weight loss program that consisted of energy restriction (reduced by approximately 500 kcal/day) and supervised aerobic exercise (5 days/wk, 45 min/day at 60% Vo(2 max); approximately 375 kcal/day). IR and insulin sensitivity were assessed by the calculation of the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI), respectively. Oxidative stress was assessed by oxidized LDL (oxLDL), myeloperoxidase (MPO), and low- and high- density lipoprotein (LDL and HDL) lipid hydroperoxide concentrations in serum. Indexes for antioxidative status included apolipoprotein A1 (apoA1) concentrations and paraoxonase-1 (PON1) activity and protein concentrations. Exercise- and diet-induced weight loss ( approximately 10%) significantly (P < 0.05) increased insulin sensitivity and reduced IR, oxLDL, and LDL lipid hydroperoxides but did not alter HDL lipid hydroperoxides or MPO concentrations. Lifestyle modification impacted systemic antioxidative status by increasing apoA1 concentrations and reducing serum PON1 protein and activity. Changes in oxidative stress were not associated with alterations in HOMA or QUICKI. Diet- and exercise-induced weight loss ( approximately 10%) improves measures of insulin sensitivity and beneficially alters biomarkers of oxidative status.     

Moderate effect of duodenal-jejunal bypass surgery on glucose homeostasis in patients with type 2 diabetes

Gastric bypass surgery causes resolution of type 2 diabetes (T2DM), which has led to the hypothesis that upper gastrointestinal (UGI) tract diversion, itself, improves glycemic control. The purpose of this study was to determine whether UGI tract bypass without gastric exclusion has therapeutic effects in patients with T2DM. We performed a prospective trial to assess glucose and β-cell response to an oral glucose load before and at 6, 9, and 12 months after duodenal-jejunal bypass (DJB) surgery. Thirty-five overweight or obese adults (BMI: 27.0 ± 4.0 kg/m(2)) with T2DM and 35 sex-, age-, race-, and BMI-matched subjects with normal glucose tolerance (NGT) were studied. Subjects lost weight after surgery, which was greatest at 3 months (6.9 ± 4.9%) with subsequent regain to 4.2 ± 5.3% weight loss at 12 months after surgery. Glycated hemoglobin (HbA(1c)) decreased from 9.3 ± 1.6% before to 7.7 ± 2.0% at 12 months after surgery (P < 0.001), in conjunction with a 20% decrease in the use of diabetes medications (P < 0.05); 7 (20%) subjects achieved remission of diabetes (no medications and HbA(1c) <6.5%). The area under the curve after glucose ingestion was ~20% lower for glucose but doubled for insulin and C-peptide at 12 months, compared with pre-surgery values (all P < 0.01). However, the β-cell response was still 70% lower than subjects with NGT (P < 0.001). DJB surgery improves glycemic control and increases, but does not normalize the β-cell response to glucose ingestion. These findings suggest that altering the intestinal site of delivery of ingested nutrients has moderate therapeutic effects by improving β-cell function and glycemic control.     

Hepatic steatosis and low cardiorespiratory fitness in youth with type 2 diabetes

The purpose of this study was to examine the association between cardiorespiratory fitness, ectopic triglyceride accumulation, and insulin sensitivity among youth with and without type 2 diabetes. Subjects included 137 youth ages 13-18 years including 27 with type 2 diabetes, 97 overweight normoglycemic controls, and 13 healthy weight normoglycemic controls. The primary outcome measure was cardiorespiratory fitness defined as peak oxygen uptake indexed to fat free mass. Secondary outcomes included liver and muscle triglyceride content determined by (1)H-magnetic resonance spectroscopy and insulin sensitivity determined by frequently sampled intravenous glucose tolerance test. Despite similar measures of adiposity, peak oxygen uptake was 11% lower (38.9 ± 7.9 vs. 43.9 ± 6.1 ml/kgFFM/min, P = 0.002) and hepatic triglyceride content was nearly threefold higher (14.4 vs. 5.7%, P = 0.001) in youth with type 2 diabetes relative to overweight controls. In all 137 youth, cardiorespiratory fitness was negatively associated with hepatic triglyceride content (r = -0.22, P = 0.02) and positively associated with insulin sensitivity (r = 0.29, P = 0.002) independent of total body and visceral fat mass. Hepatic triglyceride content was also negatively associated with insulin sensitivity (r = -0.35, P < 0.001), independent of adiposity, sex, age, and peak oxygen uptake. This study demonstrated that low cardiorespiratory fitness and elevated hepatic triglyceride content are features of type 2 diabetes in youth. Furthermore, cardiorespiratory fitness and hepatic triglyceride are associated with insulin sensitivity in youth. Taken together, these data suggest that cardiorespiratory fitness and hepatic steatosis are potential clinical biomarkers for type 2 diabetes among youth.     

Measuring aerobic cycling power as an assessment of childhood fitness

The emergence of obesity, insulin resistance, and type 2 diabetes in children requires a rational, effective public health response. Physical activity remains an important component of prevention and treatment for obesity, type 2 diabetes, and insulin resistance. Studies in adults show cardiovascular fitness to be more important than obesity in predicting insulin resistance. We recently demonstrated that a school-based fitness intervention in children who are overweight could improve cardiovascular fitness, body composition, and insulin sensitivity, but it remains unclear whether accurate assessment of fitness could be performed at the school or outside of an exercise laboratory. To determine whether new methodology using measurement of cycling power could estimate cardiovascular aerobic fitness (as defined by VO2max) in middle school children who were overweight. Thirty-five middle school children (mean age 12 +/- 0.4 years) who were overweight underwent testing on a power sensor-equipped Cycle Ops indoor cycle (Saris Cycling Group, Fitchburg, WI) as well as body composition by dual x-ray absorptiometry and VO2max by treadmill determination. Insulin sensitivity was also estimated by fasting glucose and insulin. Maximal heart rate (MHR) was determined during VO2max testing, and power produced at 80%MHR was recorded. Spearman's rank correlation was performed to evaluate associations. Mean power determined on the indoor cycle at 80% of MHR was 129 +/- 77 watts, and average power at 80% MHR divided by total body weight was 1.5 +/- 0.5. A significant correlation between watts and total body weight was seen for VO2max (P = 0.03), and significant negative correlation was seen between watts/total body weight and fasting insulin (P < 0.05). Among middle school children who were overweight, there was a significant relationship between the power component of fitness and cardiovascular aerobic fitness (measured by VO2max). This more accessible and less intimidating field-based measure of power may prove useful in predicting changes in cardiovascular fitness. Thus, accurate assessment of childhood aerobic fitness may be achievable by measurement of power, possibly within the school environment, at substantially less cost and effort than laboratory-based measurements.     

Effects of Serum Calcium and Magnesium on Heart Rate Variability in Adult Women

The present study was designed to evaluate the association of serum calcium (Ca) and magnesium (Mg) levels with heart rate variability (HRV). One hundred and sixteen adult women were recruited in this cross-sectional study. Serum Ca and Mg levels were measured, and HRV in each time and frequency domain was recorded for 5?min. Mean heart rate and standard deviation of the normal to normal interval (SDNN) and root mean square of differences of successive RR interval (RMSSD) in time domain and total power (TP), low-frequency power (LF), high-frequency power (HF), and LF/HF ratio in frequency domain were compared according to the tertiles of serum Ca and Mg levels and Ca/Mg ratio. The associations between serum Ca and Mg levels and Ca/Mg ratio with HRV were evaluated using regression analyses. Mean heart rate tended to increase from the lowest to the highest tertile of Ca levels (p?=?0.081), whereas it decreased significantly with higher Mg levels (p?=?0.026). Increasing SDNN value was observed from the lowest to the highest tertile of Mg levels (p?=?0.009). SDNN value decreased significantly from the lowest to the highest tertile of Ca/Mg ratio (p?=?0.030). Participants in the lowest tertile of Ca/Mg ratio had significantly higher TP and LF values compared to those in the middle and highest tertiles (p?<?0.05). Decreasing SDNN, TP, and LF values were significantly associated with higher Ca/Mg ratios (p?<?0.05). Associations of serum Mg level and Ca/Mg ratio with HRV could be one of the mechanisms involved in cardiovascular diseases.     

Seven days of aerobic exercise training improves conduit artery blood flow following glucose ingestion in patients with type 2 diabetes

The vasodilatory effects of insulin account for up to 40% of insulin-mediated glucose disposal; however, insulin-stimulated vasodilation is impaired in individuals with type 2 diabetes, limiting perfusion and delivery of glucose and insulin to target tissues. To determine whether exercise training improves conduit artery blood flow following glucose ingestion, a stimulus for increasing circulating insulin, we assessed femoral blood flow (FBF; Doppler ultrasound) during an oral glucose tolerance test (OGTT; 75 g glucose) in 11 overweight or obese (body mass index, 34 ± 1 kg/m2), sedentary (peak oxygen consumption, 23 ± 1 ml·kg?1·min?1) individuals (53 ± 2 yr) with non-insulin-dependent type 2 diabetes (HbA1c, 6.63 ± 0.18%) before and after 7 days of supervised treadmill and cycling exercise (60 min/day, 60-75% heart rate reserve). Fasting glucose, insulin, and FBF were not significantly different after 7 days of exercise, nor were glucose or insulin responses to the OGTT. However, estimates of whole body insulin sensitivity (Matsuda insulin sensitivity index) increased (P < 0.05). Before exercise training, FBF did not change significantly during the OGTT (1 ± 7, -7 ± 5, 0 ± 6, and 0 ± 5% of fasting FBF at 75, 90, 105, and 120 min, respectively). In contrast, after exercise training, FBF increased by 33 ± 9, 39 ± 14, 34 ± 7, and 48 ± 18% above fasting levels at 75, 90, 105, and 120 min, respectively (P < 0.05 vs. corresponding preexercise time points). Additionally, postprandial glucose responses to a standardized breakfast meal consumed under "free-living" conditions decreased during the final 3 days of exercise (P < 0.05). In conclusion, 7 days of aerobic exercise training improves conduit artery blood flow during an OGTT in individuals with type 2 diabetes.     

Prevalence of insulin resistance in a young adult population. Relationship with weight status

AimTo estimate the prevalence of insulin resistance using both the Homeostatic Model Assessment (HOMA) index and basal insulinemia, and to analyze its relationship to overweight, as measured by body mass index (BMI) and waist circumference (WC).Patients and methodsA series of 118 non-diabetic young adults aged 18 and 19 years attending a primary care health center were studied. They were contacted by telephone, and their BMI, WC, HOMA and basal insulinemia were measured, among other parameters.ResultsHOMA values ≥ P90 (HOMA ≥3.15) were found in 9.3% of the sample (50% in the obesity group). Insulinemia ≥ P90 (16,9) was found in 11%. Based on BMI, 17.8% were overweight (26.5% of men, 11.6% of women), and 6.8% were obese (6.1% of men, 7.2% of women). Based on WC, 5.71% were obese when waist was measured at the midpoint and 15.38%, when measured at the iliac crest. HOMA was found to be significantly correlated to weight increase, BMI, WC, systolic blood pressure, triglycerides, and blood glucose, while correlation was only found between insulinemia and increased WC and decreased high lipoprotein cholesterol (HDL) levels.ConclusionIn this young adult sample, increased BMI and WC were associated to increased insulin resistance. High HOMA values were found in 9.3% of subjects.     

Glucose tolerance, plasma lipoproteins and tissue lipoprotein lipase activities in body builders

Oral glucose tolerance, insulin binding to erythrocyte receptors, serum lipids, and lipoproteins, and lipoprotein lipase activities of adipose tissue and skeletal muscle were measured in nine body builders (relative body weight (RBW) 118 +/- 4%), eight weight-matched (RBW 120 +/- 5%) and seven normal-weight controls (RBW 111 +/- 3%). The body builders had 50% higher relative muscle mass of body weight (% muscle) and 50% smaller relative body fat content (% fat) than the two other groups (P less than 0.005). Maximal aerobic power was comparable in the three groups. In the oral glucose tolerance test (OGTT), blood glucose levels, and plasma insulin levels were lower (P less than 0.05) in the body builders than in weight-matched controls. Insulin binding to erythrocytes was similar in each group. On the basis of multiple linear regression analysis, 87% of the variation in plasma insulin response could be explained by body composition (% muscle and % fat) and VO2max. Plasma total cholesterol, low-density lipoprotein (LDL) cholesterol, and very low-density lipoprotein (VLDL) triglyceride concentrations were significantly lower in the body builders than in weight-matched controls. In comparison with the normal-weight group, the body builders had a lower total cholesterol level. High density lipoprotein (HDL) cholesterol, its subfractions (HDL2 and HDL3 cholesterol) and lipoprotein lipase (LPL) activities of adipose tissue and skeletal muscle were comparable in all three groups. Partial correlation analysis showed a positive relationship between plasma total triglyceride, total cholesterol and LDL cholesterol on the other hand and the % fat on the other.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of resistance training on patients with metabolic syndrome--significance of changes in muscle fiber size and muscle fiber distribution

People who are afflicted with "metabolic syndrome" exhibit multiple coronary disease risk factors such as insulin resistance, hypertension, hyperlipidemia, or obesity. Twenty-six volunteers (13 women and 13 men) with such disease risk factors (56 ± 5 years) participated in a 14-week resistance training program. Given the fact that resistance training may improve cardiometabolic parameters, the fasting total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, insulin, glucose value, homeostatic model assessment (HOMA) index, and blood pressure and body mass index (BMI) were measured before and after the training intervention. In addition, muscle biopsies from the vastus lateralis muscle of 11 of the men and 5 of the women were analyzed to determine whether changes in the muscle morphology influence the cardiometabolic parameters. Resistance training resulted in a significant increase in fasting HDL for the entire group (from 44.35 ± 9.43 to 48.57 ± 10.96 mg·dl(-1), p = 0.016). No other blood parameter changed significantly. No change was observed in the HOMA index, blood pressure, or BMI. The muscle fiber type distribution did not change, but a significant hypertrophy of muscle fibers was evident (an increase of the ellipse minor axis of 67.3 ± 16.6 to 72.1 ± 12.3 μm, p = 0.004). Moderate intensity resistance training, as was performed in our study, induces hypertrophic impulses but does not seem to have a clear positive influence on cardiometabolic risk factors. However, 2 sessions of moderate intensity resistance training per week can enhance the fasting HDL cholesterol in middle-aged subjects.     

Insulin resistance in adolescents with Down syndrome: a cross-sectional study

Background

The prevalence of diabetes mellitus is higher in individuals with Down syndrome (DS) than in the general population; it may be due to the high prevalence of obesity presented by many of them. The aim of this study was to evaluate the insulin resistance (IR) using the HOMA (Homeostasis Model Assessment) method, in DS adolescents, describing it according to the sex, body mass index (BMI) and pubertal development.

Methods

15 adolescents with DS (8 males and 7 females) were studied, aged 10 to 18 years, without history of disease or use of medication that could change the suggested laboratory evaluation. On physical examination, the pubertal signs, acanthosis nigricans (AN), weight and height were evaluated. Fasting plasma glucose and insulin were analysed by the colorimetric method and RIA-kit LINCO, respectively. IR was calculated using the HOMA method. The patients were grouped into obese, overweight and normal, according to their BMI percentiles. The EPIINFO 2004 software was used to calculate the BMI, its percentile and Z score.

Results

Five patients were adults (Tanner V or presence of menarche), 9 pubertal (Tanner II – IV) and 1 prepubertal (Tanner I). No one had AN. Two were obese, 4 overweight and 9 normal. Considering the total number of patients, HOMA was 1.7 ± 1.0, insulin 9.3 ± 4.8 μU/ml and glucose 74.4 ± 14.8 mg/dl. The HOMA values were 2.0 ± 1.0 in females and 1.5 ± 1.0 in males. Considering the nutritional classification, the values of HOMA and insulin were: HOMA: 3.3 ± 0.6, 2.0 ± 1.1 and 1.3 ± 0.6, and insulin: 18.15 ± 1.6 μU/ml, 10.3 ± 3.5 μU/ml and 6.8 ± 2.8 μU/ml, in the obese, overweight and normal groups respectively. Considering puberty, the values of HOMA and insulin were: HOMA: 2.5 ± 1.3, 1.4 ± 0.6 and 0.8 ± 0.0, and insulin: 13.0 ± 5.8 μU/ml, 7.8 ± 2.9 μU/ml and 4.0 ± 0.0 μU/ml, in the adult, pubertal and prepubertal groups respectively.

Conclusion

The obese and overweight, female and adult patients showed the highest values of HOMA and insulin.     

Insulin resistance and whole body energy homeostasis in obese adolescents with fatty liver disease

Obese adolescents are at risk of developing NAFLD and type 2 diabetes. We measured noninvasively the IHF content of obese adolescents to ascertain whether it is associated with insulin resistance and abnormal energy homeostasis. IHF content, whole body energy homeostasis, insulin sensitivity, and body composition were measured using localized hepatic (1)H-MRS, indirect calorimetry, fasting-derived and 3-h-OGTT-derived surrogate indexes (HOMA2 and WBISI), and DEXA, respectively, in 54 obese adolescents (24 female and 30 male, age 13 +/- 2 yr, BMI >99th percentile for their age and sex). NAFLD (defined as IHF content >5% wet weight) was found in 16 individuals (30%) in association with higher ALT (P < 0.006), Hb A(1c) (P = 0.021), trunk fat content (P < 0.03), and lower HDL cholesterol (P < 0.05). Individuals with NAFLD had higher fasting plasma glucose (89 +/- 8 vs. 83 +/- 9 mg/dl, P = 0.01) and impaired insulin sensitivity (HOMA2 and WBISI, P < 0.05). Meanwhile, parameters of insulin secretion were unaffected. Their reliance on fat oxidation in the fasting state was lower (RQ 0.83 +/- 0.08 vs. 0.77 +/- 0.05, P < 0.01), and their ability to suppress it during the oral glucose challenge was impaired (P < 0.05) vs. those with normal IHF content. When controlling for trunk fat content, the correlation between IHF content and insulin sensitivity was weakened, whereas the correlation with fasting lipid oxidation was maintained. In conclusion, NAFLD is common in childhood obesity, and insulin resistance is present in association with increased trunk fat content. In contrast, the rearrangement of whole body substrate oxidation in these youngsters appeared to be an independent feature.     

Acute exercise and training alter blood lipid and lipoprotein profiles differently in overweight and obese men and women

Our purpose was to elucidate effects of acute exercise and training on blood lipids-lipoproteins, and high-sensitivity C-reactive protein (hsCRP) in overweight/obese men (n = 10) and women (n = 8); age, BMI, body fat percentage, and VO(2)max were (mean ± SEM): 45 ± 2.5 years, 31.9 ± 1.4 kg·m(-2), 41.1 ± 1.5%, and 25.2 ± 1.3 mlO(2)·kg(-1)·min(-1). Before exercise training subjects performed an acute exercise session on a treadmill (70% VO(2)max, 400 kcal energy expenditure), followed by 12 weeks of endurance exercise training (land-based or aquatic-based treadmill): 3 sessions·week(-1), progressing to 500 kcal·session(-1) during which subjects maintained accustomed dietary habits. After training, the acute exercise session was repeated. Blood samples, obtained immediately before and 24 h after acute exercise sessions, were analyzed for serum lipids, lipoproteins, and hsCRP adjusted for plasma volume shifts. Exercise training increased VO(2)max (+3.67 mlO(2)·kg(-1)·min(-1), P < 0.001) and reduced body weight (-2.7 kg, P < 0.01). Training increased high-density lipoprotein (HDL) and HDL(2b)-cholesterol (HDL-C) concentrations (+3.7 and +2.4 mg·dl(-1), P < 0.05) and particle numbers (+588 and +206 nmol·l(-1), P < 0.05) in men. In women despite no change in total HDL-C, subfractions shifted from HDL(3)-C (-3.2, P < 0.01) to HDL(2b)-C (+3.5, P < 0.05) and HDL(2a)-C (+2.2 mg·dl(-1), P < 0.05), with increased HDL(2b) particle number (+313 nmol·l(-1), P < 0.05). Training reduced LDL(3) concentration and particle number in women (-1.6 mg·dl(-1) and -16 nmol·l(-1), P < 0.05). Acute exercise reduced the total cholesterol (TC): HDL-C ratio in men (-0.16, P < 0.01) and increased hsCRP in all subjects (+0.05 mg·dl(-1), P < 0.05), regardless of training. Training did not affect acute exercise responses. Our data support the efficacy of endurance training, without dietary intervention, to elicit beneficial changes in blood lipids-lipoproteins in obese men and women.     

Obesity in type 2 diabetes: prevalence, treatment trends and dilemmas

This retrospective observational study investigated the prevalence of obesity in persons with type 2 diabetes, trends in obesity resulting from the duration and treatment of diabetes, and treatment-related changes in HbA1c and body mass index (BMI). Data on 1773 type 2 diabetics (802 men and 971 women) were obtained from the CroDiabNET registry. Follow-up included the analysis of patients' age, disease duration, diabetes treatment, BMI and HbA1c values. A significantly higher rate of overweight and obesity was found in persons with type 2 diabetes as compared to the general population. A significant decrease in BMI was observed in the groups treated by diet, and in those treated by oral hypoglycaemic agents (p < 0.05), regardless of their pharmacotherapeutic group, in contrast to a significant increase in BMI observed in the groups treated with insulin (alone or in combination with oral hypoglycaemic agents) (p < 0.05). Persons with type 2 diabetes lost weight only during the first years of the disease, while with diabetes duration and insulin treatment they regained weight. A significant increase in HbA1c was observed in the groups treated with sulfonylureas (p < 0.05), whereas all other groups revealed either a significant decrease (p < 0.05) or no change in HbA1c. Our findings suggest the necessity of an integrated approach to managing type 2 diabetic patients that would simultaneously address both diabetes and obesity. Good glycaemic control is imperative and diabetes treatment should not be postponed. Because of a possible concomitant weight gain, aggressive weight control measures should be applied concurrently in order to achieve maximum treatment benefit.     

Lipoprotein Profiles in Class III Obese Caucasian and African American Women with Nonalcoholic Fatty Liver Disease

Triglyceride content in the liver is regulated by the uptake, production and elimination of lipoproteins, and derangements in these processes contribute to nonalcoholic fatty liver disease (NAFLD). Previous studies show a direct relationship between intrahepatic fat and production of apolipoprotein B100 (apoB100) containing particles, VLDL and LDL, but little consensus exists regarding changes in lipoprotein production in the development of simple steatosis (SS) versus nonalcoholic steatohepatitis (NASH). Further, ethnic variations in lipoproteins among SS and NASH are unknown as is how such variations might contribute to the differential prevalence of disease among Caucasians versus African Americans. In this study, we assessed plasma lipoprotein profiles by nuclear magnetic resonance (NMR) spectroscopy in 70 non-diabetic class III obese females recruited from the surgical weight loss clinic. Of these, 51 females were stratified by biopsy-staged NAFLD severity (histologically normal, SS, or NASH). NASH females displayed increased circulating triglycerides and increased VLDL particle number and size relative to those with histologically normal livers, while total and large LDL concentration decreased in SS versus NASH and correlated with increased insulin resistance (via HOMA2-IR). When Caucasian women were examined alone (n = 41), VLDL and triglycerides increased between normal and SS, while total LDL and apoB100 decreased between SS and NASH along with increased insulin resistance. Compared to Caucasians with SS, African American women with SS displayed reduced triglycerides, VLDL, and small LDL and a more favorable small to large HDL ratio despite having increased BMI and HOMA2-IR. These findings suggest that ApoB100 and lipoprotein subclass particle number and size can delineate steatosis from NASH in obese Caucasian females, but should be interpreted with caution in other ethnicities as African Americans with SS display relatively improved lipoprotein profiles. This may reflect variation in the relationship between dyslipidemia and NAFLD progression across gender and ethnicity.