Association of obesity and distribution of obesity with glucose tolerance and cardiovascular risk factors in the elderly.

The association of obesity and fat distribution with glucose tolerance and cardiovascular risk factor levels were investigated in a population-based study in East Finland including 396 non-diabetic men and 673 women aged from 65 to 74 years. Obese men and women (BMI greater than 27 kg/m2) had higher levels (P less than 0.001) of fasting and 2 h plasma glucose and insulin as well as total triglycerides and diastolic blood pressure, and lower levels of HDL cholesterol than normal weight men and women. Central fat distribution (the highest vs. the lowest tertile of waist-hip ratio) was associated independently of obesity with high fasting glucose (5.7 vs. 5.5 mmol/l in non-obese subjects, 5.9 vs. 5.7 mmol/l in obese subjects, P less than 0.05) and insulin levels (13.7 vs. 10.6 mU/l in non-obese subjects, 18.4 vs. 15.6 mU/l in obese subjects, P less than 0.01) and with adverse changes (P less than 0.05) in lipid and lipoprotein levels (triglycerides: 1.59 vs. 1.41 mmol/l in non-obese subjects, 1.92 vs. 1.69 mmol/l in obese subjects; HDL cholesterol: 1.33 vs. 1.43 mmol/l in non-obese subjects, 1.20 vs. 1.32 mmol/l in obese subjects). There were no marked differences in metabolic aberrations related to obesity between men and women. However, the association between waist-hip ratio and risk factors was non-linear in men whereas it was linear in women. In conclusion, obesity per se rather than its distribution was a more significant determinant of glucose and insulin as well as total triglyceride and HDL cholesterol levels in elderly subjects.     

Hypertension in obese children: fasting serum insulin levels are closely correlated with blood pressure

The relationship between blood pressure and anthropometric or metabolic factors was studied in 324 obese children aged 9.5 +/- 1.8 years (mean +/- standard deviation). Obese children had a significantly higher blood pressure than non-obese children (systolic blood pressure: 121 +/- 14 mmHg in obese children vs 112 +/- 11 mmHg in non-obese children, P less than 0.001; diastolic blood pressure: 72 +/- 9 mmHg in obese children vs 66 +/- 7 mmHg in non-obese children, P less than 0.001). When the obese children were divided into hypertensive and normotensive groups, there was a significant difference in fasting serum insulin levels between the two groups (19.3 +/- 9.3 microU/ml in the hypertensive group vs 13.0 +/- 6.1 microU/ml in the normotensive group), and a close correlation between fasting serum insulin levels and systolic blood pressure was demonstrated (r = 0.63, P less than 0.001). However, there was no significant correlation between blood pressure and the degree of obesity itself or the waist-to-hip ratio in the obese children. There was no significant correlation between blood pressure and fasting plasma glucose, serum total cholesterol, or triglycerides levels in the obese children. Moreover, the correlation between fasting insulin levels and blood pressure was shown to be independent of the degree of obesity or waist-to-hip ratio and age by multiple regression analysis. These results indicate that hyperinsulinemia itself may play an important role in the pathogenesis of hypertension in obese children.     

Serum Insulin Level Versus Blood Pressure: A Cross-sectional,Case-controlled Study in Non-obese,Middleaged Japanese Subjects with Normal Glucose Tolerance

To assess the relationship between blood pressure (BP) and serum insulin level in nonobese (body mass index (BMI) ≤ 27 kg m^?2), middle-aged (40–64 years of age) Japanese subjects with normal glucose tolerance, a three-phase study protocol was designed. First, the responses of plasma glucose and serum insulin to an oral glucose load were compared between 40 patients with untreated essential hypertension and 40 age-, sex- and BMI-matched normotensive control subjects. Second, the glucose and insulin responses to an i.v. glucose load were evaluated in 7 non-obese hypertensive, 7 non-obese normotensive and 7 obese hypertensive subjects. Third, BP and serum lipid profile were compared between 21 hyperinsulinaemic (serum insulin level (while fasting, after glucose loading, or both) > 2 SDs higher than the mean) and 21 age-, sex- and BMI-matched normoinsulinaemic subjects (serum insulin level within 1 SD of the mean). The glucose and insulin responses to the oral glucose load were comparable between the hypertensive and normotensive groups. Similarly, the glucose and insulin responses to the i.v. glucose load were comparable between the non-obese hypertensive and normotensive groups, whereas the mean AUC_insulin in the obese hypertensive group was significantly greater (p < 0.01) than that in either of the non-obese groups. The respective mean values for systolic and diastolic BPs did not differ between the hyperinsulinaemic and normoinsulinaemic groups. The mean serum triglyceride and HDL cholesterol concentrations were significantly higher (p < 0.01) and lower (p < 0.05), respectively, in the hyperinsuslinaemic than in the normoinsulinaemic group. The results suggest no association between serum insulin level and BP in non-obese, middle-aged, Japanese subjects with normal glucose tolerance.     

Insulin secretion and body composition in obesity

Plasma immunoreactive insulin levels were measured before and for 6 hr following a 100 g oral glucose load in ten normal volunteers and 17 grossly obese subjects. Eleven of the obese had an abnormal glucose tolerance, five of whom were overt diabetics. Twelve of the obese were restudied after significant weight reduction (thinned obese). Eight thinned obese subjects were also restudied 6–12 mo after completion of the weight reduction protocol. Body composition was measured in each subject prior to testing. Obesity was associated with hyperinsulinemia in the fasting state and in response to oral glucose. The obese diabetics demonstrated a delay and an impairment of insulin secretion in response to glucose. After weight reduction, elevated fasting plasma insulin levels fell in all. Insulin response to oral glucose was not different in the thinned obese with normal glucose tolerance from that observed in the normal volunteers. There was significant correlation between both fasting plasma insulin and total measurable insulin following the glucose load, and total body fat in the obese and thinned obese nondiabetics, but not in the obese overt diabetics. There was, however, significant correlation between fasting plasma insulin levels and total body fat in the diabetics who had a normal fasting blood sugar. These data indicate that the hyperinsulinemia of obesity is clearly related to the increase in total body fat. Carbohydrate intolerance occurs in those obese individuals with a limited pancreatic insulin secretory reserve, which fails to compensate for the increase in total body fat.     

肥胖患者运动血压与血糖、血浆胰岛素水平的关系

目的　探讨肥胖患者运动血压与血糖、血浆胰岛素水平的关系。方法　选取完成次极量踏车运动试验的 49例肥胖患者 (Obesity)及 45例体重正常的对照组 (Control) ,比较其静态血压 (RBP)、运动血压 (PBP)及空腹和口服 75克葡萄糖 2小时后血糖、血浆胰岛素水平。并分析肥胖组中合并运动性高血压 (PBP1)与运动血压正常者 (PBP2 )的血糖、胰岛素水平。结果　静态下两组血压无显著差异 ,负荷试验后达到运动性高血压标准者 ,肥胖组 2 1/ 49例 (42 8% ) ,对照组 8/ 45例 (17 8% ) ,P <0 0 1;运动后肥胖组的收缩压与舒张压均较对照组升高 ,特别是收缩压升高更明显 ;两组空腹血糖无显著差异 ,肥胖组的空腹胰岛素、餐后 2小时血糖及胰岛素均明显高于对照组 ;肥胖组中伴运动性高血压者的餐后 2小时血糖、胰岛素水平均高于不伴运动性高血压的肥胖患者。结论　肥胖患者血压、血糖升高可能与胰岛素水平升高有关     

肥胖对2型糖尿病患者临床特征及心脏结构功能的影响

目的 探讨肥胖对2型糖尿病患者心脏结构和功能的影响. 方法 符合WHO1999年糖尿病诊断标准的住院2型糖尿病患者270例.根据2000年亚太地区肥胖诊断标准将所有患者分为非肥胖组和肥胖组.使用M型超声心动图检测升主动脉内径(AOD)、左房内径(LAD)、左室收缩期内径(LVDs)、左室舒张期内径(LVDd)、室间隔厚度(IVS)、左室后壁厚度(LVPW)、左室短轴缩短率(FS)、射血分数(EF),采用多普勒超声检测二尖瓣E峰与A峰比值(E/A). 结果 (1)肥胖组体质量、体表面积、舒张压、空腹胰岛素、餐后胰岛素、空腹C肽、胰岛素抵抗指数(HOMA-IR)及三酰甘油高于非肥胖组,非肥胖组糖化血红蛋白及空腹血糖高于肥胖组;(2)肥胖组LAD.IVS、LVPW、左心室质量及E/A比值＜1的发生率高于非肥胖组;(3)多元逐步回归分析:非肥胖组EF与体质量指数呈负相关;肥胖组EF与收缩压呈正相关,与胆固醇、左心室质量(LVM)、空腹胰岛素呈负相关.结论 肥胖糖尿病患者存在明显左心肥大、左心舒张功能异常,与胰岛素抵抗、高三酰甘油血症并存.     

肥胖与非肥胖老年高血压患者血清生长激素水平比较及相关因素分析

目的比较肥胖与非肥胖老年高血压患者血清生长激素（GH）水平的差异,探讨其与心血管危险因素的相关性。方法根据体质量指数（BMI）及腰围（WC）,将80例老年高血压患者分为肥胖组及非肥胖组,测定WC、GH、空腹血糖（FPG）、空腹胰岛素（FINS）、血脂、纤维蛋白原（Fb）、收缩压（SBP）、舒张压（DBP）,C反应蛋白（CRP）,计算胰岛素抵抗指数（HOMA—IR）。结果（1）肥胖组GH、高密度脂蛋白胆固醇（HDL—C）低于非肥胖组,两者差异均有统计学意义（P〈0．05或P〈0．01）;（2）肥胖组FPG、FINS、三酰甘油（TG）、低密度脂蛋白胆固醇（LDL—C）、Fb、SBP、DBP、CRP、HOMA—IR高于非肥胖组,2组差异均有统计学意义（P〈0．05或P〈0．01）;（3）GH与HDL—C呈正相关,与WC、BMI、HOMA—IR、TG、TC、CRP、Fb及年龄呈负相关。结论肥胖的患者GH水平下降,并与心血管危险因素密切相关,GH水平降低可能预示心血管疾病的高风险。     

Insulin secretion and peripheral insulin sensitivity in obese children. Evidence of deficient glucose-stimulated early insulin release despite hyperinsulinemia.

Insulin secretion and peripheral insulin sensitivity were studied in 19 grossly-obese girls and 17 age-matched non-obese girls by means of the intravenous glucose tolerance test (IVGTT) and the simulated early insulin response test (SERT) respectively. SERT measures the fall in fasting blood glucose after a short infusion of insulin, performed so as to simulate the early phase of insulin release to the acute stimulus of an intravenous glucose load (ERex). In the IVGTT, the obese girls showed significantly increased early insulin response (ERend) in comparison with the non-obese girls. The glucose disappearance rate (KG) was similar in the two groups, although four obese girls had borderline low values. In the SERT, the rise in plasma insulin caused a much smaller decrease in blood glucose in the obese girls, than in the reference girls over the whole range of insulin levels studied. The relationship between insulin sensitivity and insulin secretion of each subject was evaluated from the plot of the ERex/ERend ratio vs blood glucose decrement. This showed that the hyperinsulinemia of the obese girls did not match the degree of peripheral resistance.     

Plasma catecholamine levels and lipid mobilization induced by yohimbine in obese and non-obese women

Oral yohimbine administration (0.2 mg/kg) induced lipid mobilization (increase in plasma non-esterified fatty acids, NEFA) in fasting non-obese women (body mass index BMI = 20.2 +/- 0.5, age 35.5 +/- 2.7 years) without significant action on plasma glucose, insulin levels, heart rate or blood pressure during the time-course of the experiment (240 min). Plasma norpinephrine (but not epinephrine) concentrations were increased (100 percent) after oral yohimbine administration. Oral administration of propranolol (40 mg, 60 min before yohimbine) reduced the lipid-mobilizing action of yohimbine (70 percent) during the 60 min following its administration and then totally suppressed its effect until the end of the experimental period (180 min). In fasting obese women (BMI = 36.4 +/- 2.1, age 37 +/- 3.6 years), yohimbine provoked an increase in plasma NEFA levels which was not markedly different from that observed in non-obese subjects. It had no significant effect on plasma glucose, insulin levels, heart rate or blood pressure. Plasma norepinephrine increased in the same proportions. The lipid-mobilizing effect of yohimbine in women is mainly attributable to the increase in synaptic norepinephrine with a resultant increment in lipolysis by beta-adrenergic agonism. In the standard fasting conditions (12 hours) the blockade of the antilipolytic fat cell alpha 2-adrenoceptors seems to be a minor component of the lipomobilizing effect of yohimbine. Morever, when compared with non-obese women, the lipomobilizing effect of yohimbine is not enhanced in obese women.     

Heterogeneous relationship of early insulin response and fasting insulin level with development of non-insulin-dependent diabetes mellitus in non-diabetic Japanese subjects with or without obesity.

The aim of this study was to investigate the association of insulin secretion and insulin resistance with the development of non-insulin-dependent diabetes mellitus (NIDDM) in obese (body mass index (BMI) > or = 25 kg/m2) and non-obese Japanese. Subjects were selected from persons participating a health survey, and a 100 g oral glucose tolerant test was performed. A total of 1604 non-diabetic subjects were followed for 2-8 years (mean 4.5 years). The fasting insulin level and the homeostasis model insulin resistance index (HOMA-R = fasting glucose [mmol/l] x fasting insulin [microU/ml]/22.5) were used as the index of insulin resistance, and insulinogenic index (the ratio of increment of insulin to that of blood glucose 30 min after glucose load) as a measure of early insulin response. Cox's proportional hazards analysis in the whole group showed that BMI, fasting blood glucose (FBG) and 2-h blood glucose (2-h BG) were positive predictors, and age and insulinogenic index were negative predictors of diabetes. Sex, family history, fasting insulin level and HOMA-R were not predictive of developing diabetes. In subgroup analysis, the same variables as in the whole group were predictors in non-obese, whereas only FBG and 2-h BG predicted diabetes in obese subjects. Fasting insulin level and HOMA-R were not predictive of diabetes both in non-obese and obese subjects. Eleven obese subjects, who developed diabetes despite a normal initial insulinogenic index, had significantly higher BMI, fasting insulin level and HOMA-R, compared with 258 obese subjects who did not develop diabetes. We conclude that most cases of diabetes in Japanese begin with decreased insulin secretion, but a small group of diabetes patients may start with insulin resistance, especially obese subjects.     

Obesity worsens cardiovascular risk profiles independently of hyperinsulinaemia

OBJECTIVE: To investigate whether human obesity is characterized by a worse cardiovascular risk profile (than no obesity) even in the absence of hyperinsulinaemia. SUBJECTS AND DESIGN: A total of 367 healthy subjects (247 nonobese and 120 obese) with normal glucose tolerance and without family history of diabetes mellitus. INTERVENTIONS: A 75-g oral glucose tolerance test was performed in all participants. MAIN OUTCOME MEASURES: Anthropometry, blood pressure, fasting plasma lipids and urate, plasma glucose and insulin concentrations at fasting, 1 h and 2 h after oral glucose load. RESULTS: In a multivariate linear regression analysis, body mass index was strongly related to all cardiovascular risk factors, independently of sex, age and plasma insulin. When risk factors were compared in 37 normoinsulinaemic obese subjects (plasma insulin within one standard deviation of the mean values observed in the 247 nonobese subjects), and in 37 sex- and age-matched normoinsulinaemic nonobese subjects, we found that plasma glucose levels were similar in the two groups, whereas plasma triglyceride (1.50 +/- 0.13 vs. 1.13 +/- 0.08 mmol L-1; mean +/- SE), low-density lipoprotein cholesterol (3.42 +/- 0.25 vs. 2.77 +/- 0.18 mmol L-1) and urate (290 +/- 12 vs. 255 +/- 12 mumol L-1) levels were significantly higher, and plasma high-density lipoprotein cholesterol concentrations were lower (1.27 +/- 0.04 vs. 1.46 +/- 0.06 mmol L-1) in obese than in nonobese subjects with normal plasma insulin levels (P < 0.01). Also systolic (132 +/- 2 vs. 124 +/- 2 mmHg) and diastolic (86 +/- 1 vs. 81 +/- 1 mmHg) blood pressure values were significantly higher in normoinsulinaemic obese subjects than in normoinsulinaemic nonobese individuals (P < 0.001). CONCLUSIONS: These results suggest that in human obesity a worse cardiovascular risk profile is found (than in the nonobese) independently of the presence of hyperinsulinaemia.     

Plasma islet amyloid polypeptide levels in obesity, impaired glucose tolerance and non-insulin-dependent diabetes mellitus.

We examined the response of plasma islet amyloid polypeptide (IAPP) to an oral glucose load in non-obese and obese subjects with normal glucose tolerance or impaired glucose tolerance (IGT), and in non-obese patients with non-insulin-dependent diabetes mellitus (NIDDM). Plasma IAPP response to intravenous glucagon injection in NIDDM patients was also studied. Plasma IAPP concentration was determined by a sensitive and specific radioimmunoassay. Basal levels of plasma IAPP in non-obese subjects with normal glucose tolerance, IGT and NIDDM were not significantly different from each other. Non-obese subjects with IGT showed delayed and higher plasma IAPP response to oral glucose load compared to normal non-obese subjects. In NIDDM patients, IAPP response to glucose was delayed and lower when compared to normal non-obese subjects. Basal levels of plasma IAPP in normal obese subjects and obese subjects with IGT were significantly higher than those in normal non-obese subjects. Plasma IAPP response to glucose load in these obese subjects was higher than that in normal non-obese subjects. Plasma IAPP response was decreased in diabetic patients treated with diet, oral hypoglycemic agents and insulin in that order. We conclude that the secretion of IAPP is reduced with progression of NIDDM, although it appears to be rather augmented in IGT compared to normal non-obese subjects.     

Peripheral hyperinsulinemia of simple obesity: pancreatic hypersecretion or impaired insulin metabolism?

Insulin and C-peptide levels in peripheral blood in the fasting state and after an oral glucose load were measured in 65 nondiabetic, obese subjects and 65 age- and sex-matched nondiabetic normal weight subjects. Fasting insulin and C-peptide levels were significantly higher in obese than in nonobese subjects, whereas 1 and 2 h after the oral glucose load only insulin concentrations were significantly higher in the obese subjects. C-peptide to insulin molar ratios, as well as the relation between the incremental areas of the two peptides, were used as relative measures of hepatic insulin extraction. In the fasting state the ratios between C-peptide and insulin were similar in obese and nonobese subjects, whereas after glucose they were significantly lower in the obese individuals. Similarly, the relations between C-peptide and insulin incremental areas were significantly lower in obese than in nonobese subjects. The comparison of the corresponding plasma levels and areas of C-peptide and insulin after glucose showed that for the same C-peptide value, the insulin value was higher in the obese group. Last, in obese subjects the parameter used as an estimate of hepatic removal of insulin after oral glucose inversely correlated with the fasting insulin concentration and the insulin incremental area after glucose. These results suggest that in obesity peripheral hyperinsulinemia depends on pancreatic hypersecretion of insulin in the fasting state and impaired hepatic insulin metabolism after oral glucose loading.     

Microalbuminuria and other cardiovascular risk factors in nondiabetic subjects.

The association between urinary albumin:creatinine ratio and other cardiovascular risk factors such as age, blood pressure, obesity, glycemic indices, insulin and lipid profile was examined in a population in a Chinese community consisting of 795 men (mean age 35.8 +/- 8.8 yr) and 538 women (mean age 37.9 +/- 8.9 yr) with a normal glucose tolerance defined by WHO criteria. Men with a urinary albumin:creatinine ratio above the 90th percentile had higher systolic and diastolic blood pressures, fasting plasma glucose, 2-h glucose after a 75 g oral glucose load, and fasting serum insulin. Women with high urinary albumin:creatinine values had higher systolic and diastolic blood pressures, body mass index, waist-hip ratio, fasting insulin and triglycerides. Multivariate analysis showed that only systolic blood pressure and fasting glucose in men, and diastolic blood pressure and fasting insulin in women, independently contributed to urinary albumin:creatinine. When the effect of blood pressure was eliminated by excluding subjects with systolic blood pressure > 140 and diastolic > 90 mm Hg, only fasting insulin was associated with urinary albumin:creatinine in women. No associations were found for men. We conclude that microalbuminuria may be a marker for cardiovascular disease only because of its association with blood pressure in men, while in women, there is an additional independent association with fasting serum insulin.     

Serum 25-hydroxyvitamin D is associated with insulin resistance independently of obesity in children ages 5–17

AimTo determine the association of vitamin D with insulin resistance and obesity in children.MethodsA total of 92 obese and 58 non-obese children aged 5–17 years were evaluated. Data were collected related to anthropometric (weight, height), and biochemical parameters (fasting plasma glucose, serum insulin, serum 25-hydroxyvitamin D, lipid profile, vitamin B12, parathormone) and physical examination (blood pressure, acanthosis nigricans, stria, lipomastia). Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA). HOMA-IR = fasting insulin level (μU/ml) × fasting glucose (mg/dL)/405. A HOMA-IR value >2.5 was defined as insulin resistance.ResultsAccording to the US Endocrine Society classification, vitamin D deficiency (0−20 ng/ml) was determined at significantly higher rates in the obese group than in the control group (p < 0.001). The rate of subjects with a vitamin D level of 20−30 ng/ml was significantly lower in the obese group than in the control group (p < 0.001) Within the obese group a statistically significant difference was determined between the insulin resistant and non-insulin resistant groups in respect of serum 25-hydroxyvitamin D levels (p = 0.001) and vitamin B12 levels (p = 0.001). A significant negative correlation was determined between serum 25-hydroxyvitamin D and HOMA-IR (r=−0.256, p = 0.016) and insulin (r = −0.258, p = 0.015). The systolic blood pressure (p = 0.001) and diastolic blood pressure (p = 0.003) values were significantly different in the control and obese groups. A statistically significant difference was determined between the control and obese groups in terms of the levels of insulin, HOMA-IR, HbA1c, cortisol, LDL, total cholesterol, HDL, triglyceride, hemoglobin, MCV, MPV, and calcium.ConclusionThe prevalence of vitamin D deficiency was higher in obese children compared to normal-weight and overweight children. Serum 25(OH)D levels showed a negative correlation with insulin and HOMA-IR. Serum 25(OH)D is associated with insulin resistance independently of obesity.     

The relationship between very-low-density lipoprotein lipid and measures of carbohydrate metabolism in children with different lipoprotein profiles: Bogalusa Heart Study

The relationship of VLDL lipid (cholesterol and triglycerides) levels to fasting and postglucose plasma glucose, plasma glucose, insulin, and free fatty acid (FFA) levels were examined in four subgroups of children (n = 311, ages 6 to 18 years) from a total biracial population whose earlier beta- or pre-beta-lipoprotein cholesterol levels (or both) were in the extreme quintiles or quartiles. High beta-lipoprotein cholesterol strata with or without elevated pre-beta-lipoprotein cholesterol showed significantly high levels of FFA and glucose response (mean, 30 and 60 minutes) to oral glucose load, whereas postglucose insulin responses were markedly higher in the high pre-beta-lipoprotein cholesterol strata. VLDL triglycerides related closely with fasting plasma glucose levels (r = 0.53 to 0.60, P less than 0.001) and to a lesser extent with postglucose plasma glucose response (r = 0.37 to 0.44, P less than 0.001) in all cases. For insulin and FFA, however, correlations were significant only in certain subgroups. Similar relationships were noted for VLDL cholesterol. Measurements relating to carbohydrate tolerance, age, and race accounted for 35% to 48% of the variability in VLDL lipid values. Surprisingly, fasting plasma glucose showed the highest partial regression coefficient for VLDL lipid in all subgroups except high pre-beta-lipoprotein cholesterol and low beta-lipoprotein cholesterol category, in which age was the major predictor variable. These results demonstrate that subtle abnormalities in the above-mentioned metabolic interrelationships are established early in life.     

Plasma islet amyloid polypeptide (Amylin) levels and their responses to oral glucose in Type 2 (non-insulin-dependent) diabetic patients

Summary Fasting plasma islet amyloid polypeptide concentrations and their responses to an oral glucose load were determined in non-diabetic control subjects and patients with abnormal glucose tolerance in relation to the responses of insulin or C-peptide. Plasma islet amyloid polypeptide was measured by radioimmunoassay. In the non-diabetic control subjects, fasting plasma islet amyloid polypeptide was 6.4±0.5 fmol/ml (mean ± SEM) and was about 1/7 less in molar basis than in insulin. The fasting islet amyloid polypeptide level rose in obese patients and fell in patients with Type 1 (insulin-dependent) diabetes mellitus. In non-obese patients with impaired glucose tolerance and Type 2 (non-insulin-dependent) diabetic patients without insulin therapy, the level was equal to that of the control subjects, but a low concentration of islet amyloid polypeptide relative to insulin or C-peptide was observed in the non-obese Type 2 diabetic group. The patterns of plasma islet amyloid polypeptide responses after oral glucose were similar to those of insulin or C-peptide. However, compared to non-obese patients, a hyper-response of islet amyloid polypeptide relative to C-peptide was noted in obese patients who had a hyper-response of insulin relative to C-peptide. This study suggests that basal hypo-secretion of islet amyloid polypeptide relative to insulin exists in non-obese Type 2 diabetes and that circulating islet amyloid polypeptide may act physiologically with insulin to modulate the glucose metabolism.     

Elevated plasma levels of alpha-melanocyte stimulating hormone (alpha-MSH) are correlated with insulin resistance in obese men

OBJECTIVE: The role of alpha-melanocyte stimulating hormone (MSH) in obesity has been well-documented. However, circulating alpha-MSH concentrations in obese men and their relationship with clinical indicators of obesity and glucose metabolism have not as yet been evaluated. METHODS: We measured the plasma concentrations of alpha-MSH in 15 obese and 15 non-obese male subjects. The relationship of the plasma concentrations of alpha-MSH with body mass index (BMI), body fat mass (measured by bioelectric impedance), body fat distribution (measured by computed tomography), insulin levels, insulin resistance (assessed by the glucose infusion rate (GIR) during an euglycemic hyperinsulinemic clamp study) and with the serum concentrations of leptin and TNF-alpha were also evaluated. RESULTS: In obese men, the plasma alpha-MSH concentrations were significantly increased compared with those in non-obese men (P< 0.02). The plasma levels of alpha-MSH were positively correlated with BMI (r= 0.560, P< 0.05), fasting insulin levels (r=0.528, P< 0.05) and with visceral fat area (r=0.716, P<0.01), but negatively correlated with GIR (r= -0.625, P< 0.02) in obese male subjects. There were significant correlations between plasma concentrations of alpha-MSH and visceral fat area (r=0.631, P< 0.02), and GIR (r = -0.549, P< 0.05) in non-obese male subjects. Circulating concentrations of alpha-MSH were not significantly correlated with the serum concentrations of leptin and TNF-alpha in both obese and non-obese men. CONCLUSION: Circulating concentrations of alpha-MSH are significantly increased and correlated with insulin resistance in obese men.     

体重指数和腰围与代谢综合征发生风险的比较研究

目的 比较体重指数、腰围与代谢综合征发生风险的相关性.方法 554例人选者(男316例,女238例),按照体重指数和腰围被分为周围肥胖组192例、腹部肥胖组135例和混合肥胖组237例,7年后进行随访.结果 共随访到520例.周围肥胖组代谢综合征累积发生率26.3%(49/186),腹部肥胖组代谢综合征累积发生率41.7%(50/120),混合肥胖组代谢综合征累积发生率43.0%(92/214).腹部肥胖组和混和肥胖组代谢综合征累积发生率显著高于周围肥胖组(X2分别为7.825和12.082,均P＜0.01),且基线时舒张压、甘油三酯、空腹血糖、空腹胰岛素及稳态模型评估法胰岛素抵抗指数(HOMA-IR)也显著高于前者(均P＜0.05).以有或无代谢综合征分组后基线资料比较,代谢综合征组无论男女,腰围和腰臀比均高于非代谢综合征组(P＜0.01和P＜0.05),体重指数在两组无统计学差异,并且代谢综合征组空腹血糖、空腹胰岛素和HOMA-IR显著高于非代谢综合征组(均P＜0.05).Logistic回归显示,与代谢综合征发生风险相关的因素主要为腰围(P=0.021)、腰臀比(P=0.009)、HOMA-IR(P=0.004).结论 腹部脂肪堆积及胰岛素抵抗是代谢综合征发生的两个重要因素,腰围比体重指数与代谢综合征的发生风险关系更密切.     

Effects of hyperglycaemia and hyperinsulinaemia on plasma amino acid levels in obese subjects with normal glucose tolerance

OBJECTIVE: To investigate the effects of hyperglycaemia and hyperinsulinaemia on amino acid disposal in human obesity. DESIGN: Four sequential experimental conditions: (1) overnight fasting; (2) hyperglycaemia with hyperinsulinaemia (2 h hyperglycaemic clamp at 11 mmol/l); (3) hyperglycaemia with basal insulin (1 h hyperglycaemic clamp during somatostatin infusion), (4) hyperglycaemia with resuming hyperinsulinaemia (1 h hyperglycaemic clamp after somatostatin discontinuation). SUBJECTS: Seven non-obese and seven obese non-diabetic, normo-insulinaemic subjects. MEASUREMENTS: Glucose infused to maintain steady-state hyperglycaemia. Plasma insulin, glucagon, free fatty acid and amino acid concentrations in the last 20 min of the four experimental conditions. Net rates of plasma amino acid disappearance and appearance (micromol/l per hour), calculated as the slopes of the regression of amino acid concentration on time. RESULTS: The amount of glucose infused to maintain hyperglycaemia was reduced by nearly 50% in obese subjects. During hyperinsulinaemia, FFA suppression was lower in obese subjects. In all experimental conditions plasma amino acid levels were slightly, non-significantly higher in obese than in non-obese subjects. In both groups plasma amino acids decreased slightly with ongoing fasting, decreased remarkably during hyperglycaemia-hyperinsulinaemia, rose promptly when insulin concentration was suppressed by somatostatin infusion, and declined again after somatostatin discontinuation. Also the time-course of plasma branched-chain amino acids, which paralleled that of total amino acids, was similar in the two groups. The net rates of amino acid disappearance from plasma did not differ in obese and non-obese subjects both at fasting and during hyperglycaemia-hyperinsulinaemia. Also plasma amino acid appearance during hyperglycaemia with basal insulin was not different in the two groups. CONCLUSION: The net traffic of amino acids to and from plasma in relation to insulin drive and prevailing glucose is not impaired in obese subjects with normal glucose tolerance, in spite of a decreased insulin sensitivity of glucose and lipid metabolism.