血糖调节异常者胰岛素抵抗及胰岛β细胞功能研究

目的研究胰岛素抵抗和胰岛β细胞功能与中国人血糖调节异常(IGR)的关系。方法根据口服葡萄糖耐量试验(OGTT)将209例受试者分为正常糖耐量(NGT)组、空腹血糖受损(IFG)组、糖耐量减退(IGT)组、IFG/IGT组和糖尿病(DM)患者组,用胰岛素敏感指数(ISI-COM)评价胰岛素抵抗(IR),用调整β细胞功能指数(modifiedβcell function index,MBCI)评价β细胞功能,并用早期胰岛分泌指数(△I30/△G30)评价急性期胰岛分泌功能,OGTT胰岛素曲线下面积评价二相期胰岛素分泌功能。结果IGR各组与DM组ISI-COM较NGT组有显著降低,差异有统计学意义(P0.01),而IGR各组间差异无统计学意义(P0.05)。IFG组和IGT组β细胞功能较NGT组显著降低,差异有统计学意义(P0.01),而IFG/IGT组与DM组间差异无统计学意义(P0.05)。各病例组早期胰岛分泌功能亦较NGT组有显著性降低,差异有统计学意义(P0.01),IGT组与IFG组间差异也有统计学意义(P0.01)。结论IGR各阶段均存在不同程度的IR和β细胞功能异常,其中IFG和IGT有不同的发病机制和过程,提示对于不同糖代谢异常的患者需要不同的治疗方式,以延缓血糖代谢异常的进展。     

老年人不同糖耐量状态胰岛素抵抗和胰岛β细胞功能的研究

目的观察老年人群中空腹血糖受损(IFG)、糖耐量受损(IGT)和糖调节受损(IFG/IGT)三种不同糖耐量状态下的胰岛素抵抗(IR)和胰岛β细胞功能的变化,了解其发病机制。方法筛选60~75岁的IFG40例,IGT60例,IGT/IFG40例,正常糖耐量(NGT)70例。HOMA-IR评价胰岛素抵抗,HBC I和I30/G30分别评价基础及糖负荷后早期胰岛β细胞功能。结果(1)HOMA-IR:IFG、IFG/IGT和IGT组明显高于NGT组,P<0.01,IFG/IGT组高于IFG和IGT组,P<0.01;(2)HBC I:IFG组和IFG/IGT组明显低于NGT和IGT组,P<0.01;(3)I30/G30:IGT组和IFG/IGT组明显低于NGT组及IFG组,P<0.01。结论老年人群IFG主要表现基础状态下β细胞功能受损伴有胰岛素抵抗,IGT主要表现为早期胰岛素分泌缺陷,IFG/IGT胰岛β细胞早期胰岛素分泌功能受损更明显,胰岛素抵抗更严重。     

Differences in cardiovascular risk factors, insulin resistance, and insulin secretion in individuals with normal glucose tolerance and in subjects with impaired glucose regulation: the Telde Study

OBJECTIVE: To assess the cardiovascular risk profile, the degree of insulin resistance, and beta-cell secretion in a cohort of subjects with different categories of impaired glucose regulation (IGR): impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and combined IFG/IGT. RESEARCH DESIGN AND METHODS: We studied 902 nondiabetic subjects between 30 and 80 years of age, recruited from a cross-sectional population-based study in Telde, Gran Canaria Island, Spain. Categories of glucose tolerance were defined according to 2003 modified American Diabetes Association criteria. Risk factors for cardiovascular disease, the presence of the metabolic syndrome, and indirect measures of both insulin resistance and beta-cell function were analyzed. RESULTS: A total of 132 (14.6%) participants had isolated IFG, 59 (6.5%) isolated IGT, and 48 (5.3%) combined IFG/IGT. Groups with normal glucose tolerance (NGT) and combined IFG/IGT had, respectively, the most favorable and unfavorable levels of cardiovascular risk factors, metabolic syndrome rates, and measures of insulin resistance. Subjects with IFG and IGT showed an intermediate profile between NGT and IFG/IGT categories. We found no significant differences between IFG and IGT in cardiovascular risk factors, metabolic syndrome prevalence, or insulin resistance. The IFG group exhibited a more impaired insulin secretion than those with IGT or IFG/IGT. CONCLUSIONS: Individuals with IGR, especially those with IFG/IGT, have increased values of cardiovascular risk factors and higher indexes of insulin resistance. Groups with isolated IFG and isolated IGT present similar cardiovascular risk profiles. Subjects with IFG are characterized by more defective beta-cell function than other forms of IGR.     

The significance of impaired fasting glucose versus impaired glucose tolerance: importance of insulin secretion and resistance

OBJECTIVE: The American Diabetes Association recommended substituting 2hBS (glycemia at the second hour of an oral glucose tolerance test [OGTT]) for fasting blood glucose (FBS) in screening for glucose intolerance. It is debated whether these tests measure the same abnormality and relate to defective insulin secretion or resistance. This study examines the diagnostic effectiveness of FBS versus 2hBS and their relationship with insulin secretion and resistance. RESEARCH DESIGN AND METHODS: Based on history or physical findings suggesting glucose intolerance, we enrolled 398 unselected subjects admitted to a general Internal Medicine ward. After 5 days of a weight-maintaining diet, FBS, 2hBS, and insulin were measured during OGTT. The homeostatic model assessment was used to assess beta-cell function and insulin resistance. RESULTS: Excluding 19 patients with diabetes (5%), we identified 284 subjects with normal glucose tolerance (NGT), 22 with isolated impaired fasting glucose (IFG), 59 with isolated impaired glucose tolerance (IGT), and 14 with associated IFG/IGT. The sensitivity of FBS in predicting 2hBS was 19%, specificity 93%. Positive and negative predictive values were 39% and 83%, respectively. Insulin resistance was absent in NGT and IFG and markedly elevated in IGT and IFG/IGT, whereas defective insulin release was significant only in isolated IFG. CONCLUSIONS: In unselected patients, elevated FBS depends primarily on defective insulin secretion, and impaired 2hBS on insulin resistance. Because these tests measure different alterations, they are useful in combination.     

Contributions of beta-cell dysfunction and insulin resistance to the pathogenesis of impaired glucose tolerance and impaired fasting glucose

Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) are intermediate states in glucose metabolism that exist between normal glucose tolerance and overt diabetes. Epidemiological studies demonstrate that the two categories describe distinct populations with only partial overlap, suggesting that different metabolic abnormalities characterize IGT and IFG. Insulin resistance and impaired beta-cell function, the primary defects observed in type 2 diabetes, both can be detected in subjects with IGT and IFG. However, clinical studies suggest that the site of insulin resistance varies between the two disorders. While subjects with IGT have marked muscle insulin resistance with only mild hepatic insulin resistance, subjects with IFG have severe hepatic insulin resistance with normal or near-normal muscle insulin sensitivity. Both IFG and IGT are characterized by a reduction in early-phase insulin secretion, while subjects with IGT also have impaired late-phase insulin secretion. The distinct metabolic features present in subjects with IFG and IGT may require different therapeutic interventions to prevent their progression to type 2 diabetes.     

Different mechanisms for impaired fasting glucose and impaired postprandial glucose tolerance in humans

OBJECTIVE: To compare the pathophysiology of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) in a more comprehensive and standardized fashion than has hitherto been done. RESEARCH DESIGN AND METHODS: We studied 21 individuals with isolated IFG (IFG/normal glucose tolerance [NGT]), 61 individuals with isolated IGT (normal fasting glucose [NFG]/IGT), and 240 healthy control subjects (NFG/NGT) by hyperglycemic clamps to determine first- and second-phase insulin release and insulin sensitivity. Homeostasis model assessment (HOMA) indexes of beta-cell function (HOMA-%B) and insulin resistance (HOMA-IR) were calculated from fasting plasma insulin and glucose concentrations. RESULTS: Compared with NFG/NGT, IFG/NGT had similar fasting insulin concentrations despite hyperglycemia; therefore, HOMA-IR was increased approximately 30% (P < 0.05), but clamp-determined insulin sensitivity was normal (P > 0.8). HOMA-%B and first-phase insulin responses were reduced approximately 35% (P < 0.002) and approximately 30% (P < 0.02), respectively, but second-phase insulin responses were normal (P > 0.5). NFG/IGT had normal HOMA-IR but approximately 15% decreased clamp-determined insulin sensitivity (P < 0.03). Furthermore, HOMA-%B was normal but both first-phase (P < 0.0003) and second-phase (P < 0.0001) insulin responses were reduced approximately 30%. IFG/NGT differed from NFG/IGT by having approximately 40% lower HOMA-%B (P < 0.012) and approximately 50% greater second-phase insulin responses (P < 0.005). CONCLUSIONS: Since first-phase insulin responses were similarly reduced in IFG/NGT and NFG/IGT, we conclude that IFG is due to impaired basal insulin secretion and preferential resistance of glucose production to suppression by insulin, as reflected by fasting hyperglycemia despite normal plasma insulin concentrations and increased HOMA-IR, whereas IGT mainly results from reduced second-phase insulin release and peripheral insulin resistance, as reflected by reduced clamp-determined insulin sensitivity.     

Coronary artery calcification in type 2 diabetes and insulin resistance: the framingham offspring study

OBJECTIVE: To assess risk for subclinical coronary atherosclerosis using electron beam- computed tomography in subjects with or without insulin resistance and with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT/impaired fasting glucose [IFG]) or type 2 diabetes. RESEARCH DESIGN AND METHODS: We categorized glucose tolerance by type 2 diabetes therapy (diagnosed diabetes) or with an oral glucose tolerance test (OGTT) (IFG, IGT, and OGTT-detected diabetes) and insulin resistance as an elevated fasting insulin level, in subjects attending the fifth examination (1991-1995) of the Framingham Offspring Study. A representative subset of subjects without clinical atherosclerosis was selected for electron beam computed tomography in 1998-1999 from age- and sex-stratified quintiles of the Framingham risk score. The presence of subclinical atherosclerosis was defined as the upper quartile of the Agatston score distribution (score > 170). We assessed risk for subclinical atherosclerosis using multivariable logistic regression. RESULTS: Of 325 subjects aged 31-73 years, 51% were men, 11.2% had IFG/IGT, and 9.9% had diabetes (2.8% with diagnosed diabetes); 14.5% had insulin resistance. Compared with NGT, subjects with IFG/IGT tended to be more likely (adjusted odds ratio 1.5, 95% CI 0.7-3.4) and those with diabetes were significantly more likely (2.7, 1.2-6.1) to have subclinical coronary atherosclerosis. In age- and sex-adjusted models, subjects with insulin resistance were more likely to have subclinical atherosclerosis than those without insulin resistance (2.1, 1.01-4.2), but further risk factor adjustment weakened this association. In adjusted models including insulin resistance, diabetes remained associated with risk for subclinical atherosclerosis (2.8, 1.2-6.7); diagnosed diabetes (6.0, 1.4-25.2) had a larger effect than OGTT-detected diabetes (2.1, 0.8-5.5). CONCLUSIONS: Individuals with diabetes have an elevated burden of subclinical coronary atherosclerosis. Aggressive clinical atherosclerosis prevention is warranted, especially in diagnosed diabetes.     

Abnormal glucose tolerance and increased risk for cardiovascular disease in Japanese-Americans with normal fasting glucose

OBJECTIVE: To compare the American Diabetes Association (ADA) fasting glucose and the World Health Organization (WHO) oral glucose tolerance test (OGTT) criteria for diagnosing diabetes and detecting people at increased risk for cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS: Study subjects were 596 Japanese-Americans. Fasting insulin, lipids, and C-peptide levels; systolic and diastolic blood pressures (BPs); BMI (kg/m2); and total and intra-abdominal body fat distribution by computed tomography (CT) were measured. Study subjects were categorized by ADA criteria as having normal fasting glucose (NFG), impaired fasting glucose (IFG), and diabetic fasting glucose and by WHO criteria for a 75-g OGTT as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetic glucose tolerance (DGT). RESULTS: Of 503 patients with NFG, 176 had IGT and 20 had DGT These patients had worse CVD risk factors than those with NGT . The mean values for NGT, IGT, and DGT, respectively, and analysis of covariance P values, adjusted for age and sex, are as follows; intra-abdominal fat area by CT 69.7, 95.0, and 101.1 cm2 (P < 0.0001); total CT fat area 437.7, 523.3, and 489.8 cm2 (P < 0.0001); fasting triglycerides 1.40, 1.77, and 1.74 mmol/l (P = 0.002); fasting HDL cholesterol 1.56, 1.50, and 1.49 mmol/l (P = 0.02); C-peptide 0.80, 0.90, 0.95 nmol/l (P = 0.002); systolic BP 124.9, 132.4, and 136.9 mmHg (P = 0.0035); diastolic BP 74.8, 77.7, and 78.2 mmHg (P = 0.01). CONCLUSIONS: NFG patients who had IGT or DGT had more intra-abdominal fat and total adiposity; higher insulin, C-peptide, and triglyceride levels; lower HDL cholesterol levels; and higher BPs than those with NGT. Classification by fasting glucose misses many Japanese-Americans with abnormal glucose tolerance and less favorable cardiovascular risk profiles.     

The relationship between endothelial dysfunction and oxidative stress in diabetes and prediabetes

Objective: Diabetes mellitus is associated with endothelial dysfunction and oxidative stress (OS). The aim of the present study was to determine whether increased OS and impaired endothelial function, are present in early states of diabetes, such as impaired glucose tolerance (IGT) and impaired fasting glucose (IFG). Methods: Brachial artery flow‐mediated dilatation (FMD) and nitrate‐induced dilatation were measured in 133 subjects with carbohydrate abnormalities (45 IGT, 44 IFG and 44 Type 2 diabetes mellitus) and in 46 subjects with normal glucose tolerance (NGT). Waist circumference, body mass index, blood pressure and fasting lipid profiles were obtained, and glucose and insulin values in response to a 75‐g oral glucose load were also measured. Plasma malondialdehyde (MDA) and superoxide dismutase (SOD) activity were determined. Results: Patients with diabetes and prediabetes had a higher plasma MDA concentration, but a lower plasma SOD activity than the NGT group (p = 0.006) and SOD activity was positively associated with FMD (p = 0.039). FMD were significantly reduced in the groups of subjects with abnormal carbohydrate metabolism compared with the NGT group (p = 0.035). Among the subjects with diabetes and prediabetes, FMD showed a negative correlation with fasting glucose and/or plasma glucose level at 120 min after oral glucose tolerance test (p = 0.028). Conclusions: The results showed that endothelial dysfunction and increased OS were present in subjects with IGT and IFG, indicating endothelial damage in these stages.     

Insulin secretion and insulin sensitivity pattern is different in isolated impaired glucose tolerance and impaired fasting glucose: the risk factor in Impaired Glucose Tolerance for Atherosclerosis and Diabetes study

OBJECTIVE: Isolated impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) are two risk categories for type 2 diabetes. This study compared both categories with respect to the degree of insulin secretion abnormalities and insulin resistance. RESEARCH DESIGN AND METHODS: This is a crossover comparison of a population at high risk for type 2 diabetes. The subjects were recruited from the Risk Factor in Impaired Glucose Tolerance for Atherosclerosis and Diabetes (RIAD) study. They underwent a 75-g oral glucose tolerance test, with measurement of specific insulin, C-peptide, proinsulin, and free fatty acids at baseline and every 30 min after load for 2 h. Factor analysis was performed to evaluate the importance of insulin resistance and secretion abnormalities in both categories. RESULTS: All categories of prediabetic hyperglycemia had a higher cardiovascular risk factor level when adjusted for sex, age, and BMI compared to control subjects with normal glucose tolerance. Subjects with isolated IFG were more insulin resistant than those with IGT. By contrast, subjects with isolated IGT exhibited a more severe deficit in early- and late-phase insulin secretion versus IFG subjects. As shown with factor analysis, in IFG the insulin resistance factor explained 28.4% of the variance, whereas in IGT the insulin secretion factor was dominant, explaining 31.1% of the total variance. CONCLUSIONS: Our cross-sectional data from the RIAD study demonstrate that isolated IFG and isolated IGT are different with respect to the degree of insulin resistance and anomalies in insulin secretion, and that subjects with IGT exhibit a deficit in the early and late phases of insulin secretion. This finding may be important for a differential approach in primary prevention of type 2 diabetes.     

From Pre-Diabetes to Type 2 Diabetes in Obese Youth: Pathophysiological characteristics along the spectrum of glucose dysregulation

OBJECTIVE

Impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) are considered pre-diabetes states. There are limited data in pediatrics in regard to their pathophysiology. We investigated differences in insulin sensitivity and secretion among youth with IFG, IGT, and coexistent IFG/IGT compared with those with normal glucose tolerance (NGT) and type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 24 obese adolescents with NGT, 13 with IFG, 29 with IGT, 11 with combined IFG/IGT, and 30 with type 2 diabetes underwent evaluation of hepatic glucose production ([6,6-²H₂]glucose), insulin-stimulated glucose disposal (R_d, euglycemic clamp), first- and second-phase insulin secretion (hyperglycemic clamp), body composition (dual-energy X-ray absorptiometry), abdominal adiposity (computed tomography), and substrate oxidation (indirect calorimetry).

RESULTS

Adolescents with NGT, pre-diabetes, and type 2 diabetes had similar body composition and abdominal fat distribution. R_d was lower (P = 0.009) in adolescents with type 2 diabetes than in those with NGT. Compared with adolescents with NGT, first-phase insulin was lower in those with IFG, IGT, and IFG/IGT with further deterioration in those with type 2 diabetes (P < 0.001), and β-cell function relative to insulin sensitivity (glucose disposition index [GDI]) was also lower in those with IFG, IGT, and IFG/IGT (40, 47, and 47%, respectively), with a further decrease (80%) in those with type 2 diabetes (P < 0.001). GDI was the major determinant of fasting and 2-h glucose levels.

CONCLUSIONS

Obese adolescents who show signs of glucose dysregulation, including abnormal fasting glucose, glucose intolerance or both, are more likely to have impaired insulin secretion rather than reduced insulin sensitivity. Given the impairment in insulin secretion, they are at high risk for progression to type 2 diabetes. Further deterioration in insulin sensitivity or secretion may enhance the risk for this progression.Pre-diabetes, defined as the presence of elevated fasting glucose, abnormal glucose tolerance, or both, is associated with an enhanced risk for development of type 2 diabetes in adults (1), but there are limited data to define the significance in children. A recent change in the definition of the abnormal fasting glucose to a lower level (100–125 mg/dl) has increased the prevalence of pre-diabetes in both adults and youth (2–4). It is unclear from the literature what role a defect in insulin secretion or an abnormality of insulin sensitivity might play in the impairment of glucose regulation, leading to glucose intolerance or elevated fasting plasma glucose.Epidemiological studies suggest that subjects with impaired fasting glucose (IFG) have lower insulin sensitivity and higher insulin secretion (5,6) based largely on fasting indexes of insulin sensitivity and an oral glucose tolerance (OGTT)–derived single index of insulin secretion (5). Adult studies reveal similar or lower insulin sensitivity in subjects with impaired glucose tolerance (IGT) compared with those with IFG who have lower insulin secretion (7,8). These studies are contrasted with clamp studies in Pima Indians showing similar insulin sensitivity in subjects with IFG and IGT but lower insulin secretion in those with fasting dysglycemia (9).Pediatric data are limited. In overweight Latino children with a family history of type 2 diabetes (10), children with impaired versus normal fasting glucose had no significant differences in insulin sensitivity or acute insulin response. However, the glucose disposition index (GDI), or insulin secretion relative to insulin sensitivity, was significantly reduced (15% lower) in children with IFG. A more recent study in obese adolescents revealed that subjects with IFG had decreased glucose sensitivity of first-phase insulin secretion and liver insulin sensitivity, whereas those with IGT had more severe degrees of peripheral insulin resistance compared with subjects with normal glucose tolerance (NGT) (11). We recently demonstrated that insulin secretion relative to insulin sensitivity shows a significantly declining pattern: highest in youth with NGT, intermediate in youth with IGT, and lowest in youth with type 2 diabetes (12).In an attempt to clarify the controversy concerning the metabolic derangements in the different categories of the pre-diabetes state, the aims of the present study were to 1) to investigate the metabolic characteristics of insulin sensitivity and secretion in obese youth, with IFG versus IGT, of similar body composition and abdominal adiposity and 2) to compare them not only with those with NGT but also with children with type 2 diabetes.     

探讨糖尿病前期患者血浆IL-18、PAI-1水平变化与胰岛素抵抗的相关性

目的探讨血浆白细胞介素-18(IL-18)、纤溶酶原激活物抑制物-1(PAI-1)水平变化与Ⅱ型糖尿病发病危险因素的关系.方法 设立健康人对照(NGT)组、糖耐量减低( IGT )组、空腹血糖受损合并糖耐量减低(IFG/IGT)组,每组各100例.测定各受试者血浆 IL-18、PAI-1、血清空腹胰岛素、空腹血糖、餐后2 h血糖,应用稳态模型评估法评价胰岛素抵抗(HOMA-IR).结果 IGT组、IFG/IGT组血浆 IL-18、PAI-1 水平均高于NGT组(P<0.01).IFG/IGT组血浆 IL-18、PAI-1 水平均高于IGT组(P<0.05).相关分析显示IL-18、PAI-1 水平与空腹血糖、餐后2 h血糖、HOMA-IR呈正相关(P<0.01).结论血浆 IL-18、PAI-1 水平升高可能是加重糖尿病前期患者胰岛素抵抗的危险因素;在糖尿病前期,IL-18、PAI-1可能参与了Ⅱ型糖尿病的发生、发展.     

减少样本量的静脉葡萄糖耐量试验检测胰岛素抵抗状态

目的运用减少样本量的静脉葡萄糖耐量试验（frequently sampled intravenous glucose tolerance test,FSIGT）对不同糖耐量受试者的胰岛素抵抗状态进行检测。方法2008年6月—2009年6月,我们选取了160例不同糖耐量状态的非糖尿病患者,分为正常糖耐量组（NGT）、空腹血糖异常组（IFG）、糖耐量减退组（IGT）及（IFG＋IGT）组,通过口服糖耐量试验评价其糖耐量状态,运用基于Bergman最小模型技术的减少样本量的FSIGT评价受试者的胰岛素抵抗程度。结果4组对象的年龄、体质指数（BMI）、腰臀比（WHR）、收缩压、舒张压、吸烟史和血脂参数各组间比较差异无统计学意义（P〉0.05）,各组由FSIGT获得的胰岛素抵抗指数（FSIGT-ISI）值显示,虽IFG、IGT及IFG＋IGT组均低于NGT组,但仅IGT组其值显著低于NGT组,具有统计学意义（P〈0.05）。结论应用FSIGT进行人群中胰岛素抵抗状态检测,对于IGT的筛查、早期诊断糖尿病及尽早采取预防措施具有重要的指导意义。     

糖耐量受损者胰岛素抵抗和β细胞功能的研究

目的　探讨糖耐量受损 (IGT)患者胰岛素抵抗、β细胞功能和相关的代谢改变。 方法　对 6 4例血糖正常者 (NGT)和 97例IGT患者进行口服葡萄糖耐量试验 (OGTT)、胰岛素释放试验 ,并测定其血脂、血压、体重指数 (BMI)和腰臀比值 (WHR)。结果　与NGT组比较 ,IGT组空腹胰岛素水平、OGTT后胰岛素曲线下面积显著升高 (P <0 0 5 ) ;胰岛素敏感指数、初期胰岛素分泌指数明显降低 (P <0 0 1) ;胰岛素敏感指数依次与腰臀比值、BMI、甘油三脂 (TG)、高密度脂蛋白 胆固醇 (HDL C)、空腹血糖和舒张压相关 ;IGT患者TG、舒张压、收缩压、BMI和腰臀比值明显增高 ,HDL C明显降低。结论　IGT患者存在胰岛素抵抗和 β细胞功能异常并伴有多种代谢紊乱。     

Plasma retinol-binding protein-4 concentrations are elevated in human subjects with impaired glucose tolerance and type 2 diabetes

OBJECTIVE: The dysregulation of adipokines is closely associated with the pathogenesis of insulin resistance and type 2 diabetes. Retinol-binding protein-4 (RBP4), a new adipokine, was recently reported to provide a link between obesity and insulin resistance. Here, we examined the relation between plasma RBP4 concentrations and various metabolic parameters in humans. RESEARCH DESIGN AND METHODS: An enzyme-linked immunosorbent assay was developed to measure human RBP4 plasma concentrations, which were then compared with various parameters related to insulin resistance in subjects with normal glucose tolerance (NGT; n = 57), impaired glucose tolerance (IGT; n = 48), and type 2 diabetes (n = 49). RESULTS: Plasma RBP4 concentrations were higher in the IGT and type 2 diabetic groups than in the NGT group (median 18.9 [range 11.2-45.8], 20.9 [9.9-48.5], and 18.1 microg/ml [9.3-30.5], respectively). However, no difference was found between plasma RBP4 concentrations in the IGT and type 2 diabetic groups. Plasma RBP4 concentrations were found to be associated with sex, waist circumference, fasting plasma glucose, and insulin resistance. Of these, sex and fasting plasma glucose levels were found to be independent determinants of plasma RBP4 concentration. CONCLUSIONS: Plasma RBP4 concentrations were found to be elevated in subjects with IGT or type 2 diabetes and to be related to various clinical parameters known to be associated with insulin resistance.     

血糖调节异常者血脂代谢的初步研究

目的初步评价血糖调节受损患者血脂代谢异常情况。方法检测糖耐量正常(NGT)、单纯空腹血糖异常(IFG)、单纯糖耐量异常(IGT)、空腹血糖异常合并糖耐量异常(IFG IGT)和糖尿病(DM)患者空腹血糖和餐后2 h血糖及空腹血清总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、载脂蛋白A-I(apo A-I)和载脂蛋白B(apo B)水平,计算非高密度脂蛋白胆固醇(non-HDL-C)和血浆致动脉硬化指数(AIP),比较各组间血清脂质成分的差异。结果IFG组血清TC、LDL-C、non-HDL-C和apo B水平较NGT组明显升高(P<0.01),而TG、HDL-C、AIP差异无统计学意义(P>0.05)。IGT组血清TC、TG、LDL-C、non-HDL-C、apo A-I、apo B和AIP水平较NGT组显著升高(P<0.01),前6项指标与IFG IGT组差异无统计学意义(P>0.05)。IFG IGT组与NGT组比较,各指标差异均有统计学意义(P<0.01);HDL-C、non-HDL-C和AIP水平与IFG组比较差异有统计学意义(P<0.01)。DM组表现出典型的DM性脂代谢紊乱伴AIP水平显著异常。non-HDL-C和apo B间存在良好的相关性(P<0.01)。结论血糖调节受损者不同程度的存在血脂代谢异常,主要表现为TC、TG、LDL-C、non-HDL-C和apo B水平的升高和HDL-C、apo A-I的降低,伴不同程度AIP水平的改变。     

不同糖代谢水平血清脂联素与胰岛素抵抗及血管舒张功能相关性研究

目的 研究不同糖代谢水平人群的血清脂联素与胰岛素抵抗、血管舒张功能的相关性.方法 体检人群中经口服葡萄糖耐量试验(OGTT)筛选出糖耐量正常(NGT)17例,空腹血糖调节受损(IFG)22例,糖耐量受损(IGT)23例、2型糖尿病(T2DM)21例,检测血清脂联素(APN)水平;用HOMA-IR和HOMA-β指数分别评价胰岛素抵抗指数、B细胞功能指数;采用高分辨率血管外超声检测血流介导的内皮依赖性血管舒张功能(EDVD)和硝酸甘油介导的内皮非依赖性血管舒张功能(EIVD).结果 在NGT,IFG,IGT,DM组,APN和EDVD水平依次降低;HOMA-IR逐渐增高.校正了年龄、性别、体质量指数、腰臀比后,APN与HOMA-IR呈负相关(r=-0.353,P<0.01),与EDVD和EIVD呈正相关(r分别为0.391,0.375,P<0.01),APN与HOMA-β无关(P>0.05);EDVD与HOMA-IR无关(P>0.05).多元逐步回归分析以APN为应变量,HOMA-IR进入方程(P<0.01);以EDVD为应变量,APN进入方程(P<0.05)HOMA-IR未进人方程.结论 T2DM 前期已经存在APN降低、胰岛素抵抗、血管内皮功能损害.APN与胰岛素抵抗负相关;与血管内皮功能正相关.APN与内皮依赖性血管舒张功能的关系独立于胰岛素抵抗.

Abstract：

Objective To study the correlation between serum adiponectin along with insulin resistanee and vascular dilation function in patients with different rates of glucose metabolism.Method A total of 83 patients aged 50-65 years,including 17 with normal glucose tolerance(NGT),22 with impaired fasting glucose (IFG),23 with impaired glucose tolerance(IGT)and 21 with diabetes(DM)were enrolled. Serum adiponectin was measured,and homeostasis model assessment for insulin resistance index (HOMA-IR)and B cell function index were used to evaluate the function of insulin secretion before and during oral glucose tolerance test(OGTr).The brachial artery responses to flow-mediated endothelium-dependent vascular dilation(EDVD)and nitroglycerin-mediated vascular dilation (EIVD) were evaluated by using the vascular ultrasound with high resolution.Results The serum adiponectin and EDVD decreased that the degrees of reduction from slightness to greatness were in turn from NGT,IFG,IGT to DM,whereas,the insulin resistance index (HOMA-IR) increased just in reverse order.Adiponectin was negatively associated with HOMA-IR(r=-0.353,P<0.01)but positively associated with EDVD and EIVD(rl=0.391,r2=0.375,P<0.01),and was not associated with HOMA-B.On the other hand,EDVD was not associated with HOMA-IR(P>0.05).In a multiple regression analysis with a stepwise manner to predict adiponectin concentration and EDVD.HOMA-IR was supposed to predict adiponectin concentration.Meanwhile APN but not HOMA-IR was used to predict EDVD(P<0.05).Condusions The decrease in serum adiponectin,endothelial dysfunction and insulin resistance can be observed in the early stage of impaired glucose metabolism. Serum adiponectin concentration appears to be associated with vascular function and insulin resistance.The association between serum adiponectin concentration and vascular function seems to be independence from its link with insulin resistance index.     

Metabolic characteristics in individuals with impaired glucose homeostasis

We sought to clarify whether impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or both (IFG/IGT) represent the most severe impairment in insulin resistance (IR) and insulin secretion. Among the 159 Chinese subjects, 21 were diagnosed as having IFG, 103 as having IGT and 35 as having both. IR and beta-cell function were assessed using homeostatic model assessment (HOMA) and an insulin-suppression test (IST). No differences were evident between the groups in blood pressure, body mass index, plasma insulin fasting levels and lipid profiles. However, plasma 2-h insulin levels were higher in the IGT and IFG/IGT groups. Beta-cell functions were not different between these groups. But, the result of glucose tolerance was different, in which the IFG/IGT and IFG groups displayed higher insulin sensitivity than IGT via HOMA instead of no difference via IST in the three patient groups.     

Impaired glucose tolerance is a risk factor for cardiovascular disease, but not impaired fasting glucose. The Funagata Diabetes Study.

OBJECTIVE: To determine whether the new category of impaired fasting glucose (IFG) recently proposed by the Expert Committee of the American Diabetes Association is a risk factor for cardiovascular disease. RESEARCH DESIGN AND METHODS: Death certificates and residence transfer documents from the cohort population consisting of participants of the diabetes prevalence study in Funagata, Yamagata prefecture, Japan, 1990-1992, were analyzed up through the end of 1996. First, the cohort population was classified into three groups: normal glucose tolerance (NGT) (n = 2,016), impaired glucose tolerance (IGT) (n = 382), and diabetic (n = 253). Then the same population was reclassified into normal fasting glucose (NFG), IFG, and diabetic. The cumulative survival rates among the groups were compared using the classical life-table method, and age-adjusted analyses, the person-year method, and Cox's proportional hazard model were adopted. RESULTS: At the end of seven observed years, the cumulative survival rates from cardiovascular disease of IGT and diabetes were 0.962 and 0.954, respectively, both significantly lower than that of NGT (0.988). The Cox's proportional hazard model analysis showed that the hazard ratio of IGT to NGT on death from cardiovascular disease was 2.219 (95% CI 1.076-4.577). However, the cumulative survival rate of IFG from cardiovascular disease was 0.977, not significantly lower than that of NFG (0.985). The Cox's hazard ratio of IFG to NFG on death from cardiovascular disease was 1.136 (0.345-3.734), which was not significant either. CONCLUSIONS: IGT was a risk factor for cardiovascular disease, but IFG was not.     

Predictors of changes in glucose tolerance status in obese youth

OBJECTIVE: Type 2 diabetes in obese youth is an emerging problem. The metabolic and anthropometric predictors of change in glucose tolerance status in obese youth are unknown. RESEARCH DESIGN AND METHODS: A total of 117 obese children and adolescents were studied by performing an oral glucose tolerance test (OGTT) at baseline and after approximately 2 years. Data from both OGTTs and changes in weight were examined to identify youth at highest risk for developing diabetes and the factors that have the strongest impact on glucose tolerance. RESULTS: Eighty-four subjects had normal glucose tolerance (NGT) and 33 impaired glucose tolerance (IGT) at baseline. Eight subjects (all of whom had IGT at baseline) developed type 2 diabetes, whereas 15 subjects with IGT reverted to NGT. In this cohort, severe obesity, impaired glucose tolerance, and African-American background emerged as the best predictors of developing type 2 diabetes, whereas fasting glucose, insulin, and C-peptide were nonpredictive. Changes in insulin sensitivity, strongly related to weight change, had a significant impact on the 2-h glucose level on the follow-up study. CONCLUSIONS: Severely obese children and adolescents with IGT, particularly of African-American descent, are at very high risk for developing type 2 diabetes over a short period of time. Parameters derived from an OGTT and not fasting samples can serve as predictors of changes in glucose tolerance.