Associations of glucose control with insulin sensitivity and pancreatic beta-cell responsiveness in newly presenting type 2 diabetes.

We examined the ability of indices of insulin sensitivity and pancreatic beta-cell responsiveness to explain interindividual variability of clinical measures of glucose control in newly presenting type 2 diabetes. Subjects with newly presenting type 2 diabetes (n = 65; 53 males and 12 females; age, 54 +/- 1 yr; body mass index, 30.5 +/- 0.7 kg/m(2); mean +/- SE) underwent an insulin-modified iv glucose tolerance test to determine minimal model-derived insulin sensitivity (S(I)), glucose effectiveness, first-phase insulin secretion, and disposition index. Subjects also underwent a standard meal tolerance test (MTT) to measure fasting/basal (M(0)) and postprandial (M(I)) pancreatic beta-cell responsiveness. Stepwise linear regression used these indices to explain interindividual variability of fasting and postprandial plasma glucose and insulin concentrations and glycated hemoglobin (HbA(1C)). All measures of pancreatic beta-cell responsiveness (M(0), M(I), and first-phase insulin secretion) were negatively correlated with fasting plasma glucose (P < 0.01) and positively correlated with fasting plasma insulin (FPI) and insulin responses to MTT (P < 0.05). S(I) demonstrated negative correlation with FPI (P < 0.001) but failed to correlate with any glucose variable. M(I) followed by disposition index (composite index of insulin sensitivity and pancreatic beta-cell responsiveness) were most informative in explaining interindividual variability. It was possible to explain 70-80% interindividual variability of fasting plasma glucose, FPI, HbA(1C), and insulin responses to MTT, and only 25-40% interindividual variability of postprandial glucose. In conclusion, postprandial insulin deficiency is the most powerful explanatory factor of deteriorating glucose control in newly presenting type 2 diabetes. Indices of insulin sensitivity and pancreatic beta-cell responsiveness explain fasting glucose and HbA(1C) well but fail to explain postprandial glucose.     

Plasma dipeptidyl peptidase-IV activity in patients with type-2 diabetes mellitus correlates positively with HbAlc levels, but is not acutely affected by food intake

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide are incretin hormones, secreted in response to meal ingestion. The incretin hormones stimulate insulin secretion and are essential for the maintenance of normal plasma glucose concentrations. Both incretin hormones are metabolized quickly by the enzyme dipeptidyl peptidase-IV (DPP-IV). It is well known that type-2 diabetic patients have an impaired incretin effect. Therefore, the aim of the present study was to investigate plasma DPP-IV activity in the fasting and the postprandial state in type-2 diabetic patients and control subjects. DESIGN: The study included two protocols. Protocol one involved 40 fasting type-2 diabetic patients (28 men); age 61 +/- 1.4 (mean +/- s.e.m.) years; body mass index (BMI) 31 +/- 0.6 kg/m(2); HbAlc 7.2 +/- 0.2%; and 20 matched control subjects (14 men) were studied. Protocol two involved eight type-2 diabetic patients (six men); age 63 +/- 1.2 years; BMI 33 +/- 0.5 kg/m(2); HbAlc 7.5 +/- 0.4%; eight matched control subjects were included. METHODS: In protocol one, fasting values of DPP-IV activity were evaluated and in protocol two, postprandial DPP-IV activity during a standard meal test (566 kcal) was estimated. RESULTS: Mean fasting plasma DPP-IV activity (expressed as degradation of GLP-1) was significantly higher in this patient group compared with the control subjects (67.5 +/- 1.9 vs 56.8 +/- 2.2 fmol GLP-1/h (mean +/- s.e.m.); P=0.001). In the type-2 diabetic patients, DPP-IV activity was positively correlated to FPG and HbAlc and negatively to the duration of diabetes and age of the patients. No postprandial changes were seen in plasma DPP-IV activity in any of the groups. CONCLUSIONS: Plasma DPP-IVactivity increases in the fasting state and is positively correlated to FPG and HbAlc levels, but plasma DPP-IV activity is not altered following meal ingestion and acute changes in plasma glucose.     

Genetic polymorphisms in peroxisome proliferator-activated receptor gamma are associated with Type 2 diabetes mellitus and obesity in the Korean population.

AIMS: We examined whether the common polymorphisms of the peroxisome proliferator-activated receptor-gamma (PPARgamma) gene are associated with Type 2 diabetes or obesity in the Korean population. METHODS: We genotyped two common PPARgamma polymorphisms (Pro12Ala and 161C > T) and examined their association with the clinical phenotypes found in 684 patients with Type 2 diabetes mellitus and 291 non-diabetic control subjects. RESULTS: The 12Ala allele was less frequent in the Type 2 diabetic patients than in the non-diabetic control subjects (0.036 vs. 0.053, P = 0.024). The allele frequencies of the 161C > T polymorphism did not differ between the control and Type 2 diabetic group (0.158 vs. 0.173). In the non-diabetic controls, those with the T allele had lower BMI and fasting serum triglyceride (TG) concentrations than those with the C/C homozygote (22.7 +/- 2.9 vs. 23.8 +/- 3.2 kg/m2, P = 0.002; 1.45 +/- 0.81 vs. 1.65 +/- 0.83 mmol/l, P = 0.03, respectively). The 12Ala-161T haplotype was associated with a decreased risk for Type 2 diabetes (OR = 0.47, P = 0.009), whereas the 12Pro-161T haplotype was associated with lower BMI and lower fasting serum TG (22.5 +/- 2.8 vs. 23.7 +/- 3.2 kg/m2, P = 0.004; 1.41 +/- 0.87 vs. 1.64 +/- 0.79 mmol/l, P = 0.02, respectively). CONCLUSIONS: The PPARgamma 12Ala allele was associated with a reduced risk of Type 2 diabetes, whereas the PPARgamma 161T allele was associated with lower BMI and fasting serum TG concentrations in the Korean subjects. The subjects with 12Ala-161T haplotypes had a reduced risk of Type 2 diabetes.     

Gastric bypass alters the dynamics and metabolic effects of insulin and proinsulin secretion.

AIMS: Hyperproinsulinaemia is associated with obesity and is a risk factor for Type 2 diabetes. We explored the dynamics of proinsulin and insulin and postprandial effects on glucose and lipids in subjects who had undergone gastric bypass (GBP) surgery compared with morbidly obese (MO) subjects and normal weight control subjects (NW). METHODS: Subjects free from diabetes were recruited: 10 previously MO subjects [body mass index (BMI) +/- sd, 34.8 +/- 6.2 kg/m2] who had undergone GBP surgery, 10 MO subjects (BMI 44 +/- 3.1 kg/m2) and 12 NW control subjects (BMI 23.2 +/- 2.4 kg/m2). After an overnight fast, a standard meal (2400 kJ) was ingested and glucose, proinsulin, insulin free fatty acids and triglycerides were determined up to 180 min. RESULTS: Fasting proinsulin was similar in the GBP group and NW control subjects, but threefold increased in MO subjects (P < 0.05). Postprandial AUC for glucose was similar in the three groups and AUC for proinsulin was high in MO, intermediate in the GBP group and lowest in NW control subjects (P for trend = 0.020). Postprandial proinsulin at 60 min was similar in the GBP group and MO subjects and twofold higher than in NW control subjects. Postprandial proinsulin at 180 min was normal in the GBP group, but fivefold increased in MO subjects (P = 0.008). Insulin increased rapidly at 30 min in the GBP group and was normal at 90 min, whereas insulin was still increased at 90-180 min in the MO subjects (P < 0.001). CONCLUSIONS: MO subjects, free from diabetes, have elevated proinsulin concentrations in the fasting as well as the postprandial phase. After GBP surgery markedly lower fasting and postprandial proinsulin concentrations were observed, although BMI was higher compared with NW control subjects.     

Factors predicting the blood glucose lowering effect of a 30-day very low calorie diet in obese Type 2 diabetic patients.

OBJECTIVE: To identify factors which predict the blood glucose lowering effect of monotherapy with a 30-day very low calorie diet (VLCD) in obese Type 2 diabetic patients. A responder was a priori defined as a patient with a fasting plasma glucose (FPG) level < 10 mmol/l on day 30. RESEARCH DESIGN AND METHODS: In 17 obese patients (BMI 37.6 +/- 5.6 (mean +/- SD) kg/m(2)) with Type 2 diabetes, all blood glucose lowering medication (including insulin) was discontinued on day -1 followed by a 30-day VLCD. On day 2 and 30 of the VLCD an intravenous glucose tolerance test (IVGTT) was performed. RESULTS: Of the 14 patients who completed the 30-day VLCD, eight qualified as responder. Responders and non-responders could be distinguished by day 2. Responders had a shorter duration of Type 2 diabetes and higher fasting serum insulin, C-peptide and HOMA-beta-values. In addition, responders displayed a more prominent second-phase insulin response following i.v. glucose loading and higher k-values. In a stepwise discriminant analysis, the change in FPG from day 0 to day 2 (responders +0.64 +/- 2.3, non-responders +4.15 +/- 3.3 mmol/l, P = 0.035) in combination with the area under the curve of insulin (AUC) above baseline during an IVGTT on day 2 (responders 571 +/- 236, non-responders 88 +/- 65 mU*50 min, P < 0.001), distinguished responders completely from non-responders. CONCLUSION: Preservation of the capacity of beta-cells to secrete insulin predicts a favourable metabolic response to a VLCD in obese Type 2 diabetic patients.     

Inhibition of dipeptidyl peptidase IV activity by oral metformin in Type 2 diabetes.

AIMS: Glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) are important insulinotropic hormones that enhance the insulin secretory response to feeding. Their potential for treating Type 2 diabetes is limited by short biological half-life owing to degradation by dipeptidyl peptidase IV (DPP IV). We investigated the acute effects of metformin on DPP IV activity in Type 2 diabetes to elucidate inhibition of DPP IV as a possible mechanism of action. METHODS: Eight fasting subjects with Type 2 diabetes (5M/3F, age 53.1+/-4.2 years, BMI 36.8+/-1.8 kg/m2, glucose 8.9+/-1.2 mmol/l, HbA1c 7.8+/-0.6%) received placebo or metformin 1 g orally 1 week apart in a random, crossover design. RESULTS: Following metformin, DPP IV activity was suppressed compared with placebo (AUC0-6 h 3230+/-373 vs. 5764+/-504 nmol ml/l, respectively, P=0.001). Circulating glucose, insulin and total GLP-1 were unchanged. Metformin also concentration-dependently inhibited endogenous DPP IV activity in vitro in plasma from Type 2 diabetic subjects. CONCLUSION: Oral metformin effectively inhibits DPP IV activity in Type 2 diabetic patients, suggesting that the drug may have potential for future combination therapy with incretin hormones.     

Relative role of insulin resistance and beta-cell dysfunction in the progression to type 2 diabetes--The Kinmen Study

This study compared the relative role of insulin resistance and beta-cell dysfunction (both assessed using the HOMA method) with glucose intolerance conditions in the progression to type 2 diabetes among a high risk group of subjects with fasting plasma glucose (FPG) 5.6-7.0 mmol/l in Kinmen, Taiwan. Data were collected during a continuing prospective study (1998-99) of a group of Taiwanese subjects at high-risk of developing type 2 diabetes who had fasting hyperglycemia (5.6-7.0 mmol/l) and exhibited 2-h postload glucose concentrations <11.1 mmol/l from 1992-94 to 1995-96. Among 644 non-diabetic subjects at baseline, 79.8% (514/644) had at least one follow-up examination. There were 107 new cases of diabetes diagnosed by 1999 WHO criteria in 2918.7 person-years of follow-up. The incidence rate was 3.67%/year (107/2918.7). After adjustment for other possible associative variables, including gender, age, BMI, waist circumference, insulin resistance, and beta-cell dysfunction, Cox's hazard model showed that those individuals with isolated IFG (impaired fasting glucose) and those individuals with isolated IGT (2-h glucose impairment) exhibited similar risk of developing diabetes. Those individuals with isolated IFG and isolated IGT showed a comparable impairment of basal or hepatic insulin sensitivity, but those individuals with isolated IFG had a greater beta-cell dysfunction by the HOMA method.     

Parallel changes of proinsulin and islet amyloid polypeptide in glucose intolerance

Elevated proinsulin secretion and islet amyloid deposition are both features of Type 2 diabetes but their relationship to beta-cell dysfunction is unknown. To determine if islet amyloid polypeptide (IAPP) secretion is disproportionate with other beta-cell products at any stage of glucose intolerance, 116 subjects were studied. Non-diabetic subjects with equivalent body mass index (BMI) were assigned to three groups, (i) normal fasting glucose, fpg<5.5 mmol l(-1); (ii) intermediate fasting glucose, fpg> or =5.5<6.15 mmol l(-1); (iii) impaired fasting glucose (IFG), fpg> or =6.1<7.0 mmol l(-1). Diabetic subjects were divided according to therapy (9 diet, 19 tablet, and 11 insulin). IAPP, C-peptide and proinsulin were measured fasting and at the end of a 1-h glucose infusion. Fasting C-peptide, IAPP and proinsulin were significantly elevated in the IFG group compared with the other non-diabetic groups (P<0.02); fasting IAPP/C-peptide and proinsulin/C-peptide were 1-2% in all non-diabetic groups. Fasting and 1-h proinsulin and proinsulin/C-peptide were higher in diabetic compared with non-diabetic subjects (P<0.01). IAPP and IAPP/C-peptide in diabetic groups were similar to that in non-diabetic subjects but reduced in the insulin-treated group (P<0.01). Proinsulin was disproportionately increased compared with C-peptide and IAPP in Type 2 diabetes particularly in severe beta-cell failure implying more than one concurrent beta-cell pathology.     

空腹血糖受损诊断标准下调的合理性分析

目的　探讨空腹血糖受损 (IFG)诊断点从 6.1mmol/L下调至 5 .6mmol/L的合理性。方法对1986年入选的 468名非糖尿病人群〔3 41例正常糖耐量 (NGT) ,12 7例糖耐量受损 (IGT)〕在 1988年 ,1990年和 1992年分别进行OGTT复查 ,测定空腹血糖 (FPG)及 2h血糖 (2hPG)。以COX模型分析不同基线血糖水平增加糖尿病的风险。结果　 (1) 10 9例 6年后发生糖尿病。COX成比例风险模型分析校正年龄、性别、体重指数 (BMI)影响后发现FPG与 2型糖尿病发病显著相关 (P =0 .0 0 0 1)。基线FPG 5 .6～ 6.0mmol/L组糖尿病发病危险性比FPG <5 .6mmol/L组已显著增加 ,RR为 3 .3 (95 %CI 2 .0～ 5 .3 ,P =0 .0 0 0 1)。 (2 )受试者工作特征 (ROC)曲线分析FPG预测糖尿病发病的最佳阈值是 5 .6mmol/L ,以FPG 5 .6mmol/L为诊断点IFG预报糖尿病发病的灵敏度、特异度、阳性预测值分别为 45 .0 % ,92 .8%和 65 .3 %。 (3 )NGT个体中COX成比例风险模型校正年龄、性别、BMI后显示 ,FPG分组 (5 .0～ 6.0mmol/L与 <5 .0mmol/L)与糖调节受损 (IGR ,包括IFG或IGT)发生显著正相关 (P =0 .0 0 7)。ROC曲线显示 ,FPG预测糖耐量恶化而进展为DM或IGR的最佳阈值为 5 .3mmol/L。结论　 (1)本组非糖尿病人群中FPG预测糖尿病发病的最佳阈值为 5 .6mmol/L     

Fasting and daylong triglycerides in obesity with and without type 2 diabetes

Postprandial hypertriglyceridemia associated with insulin resistance is one of the cardiovascular risk factors in obesity and type 2 diabetes. It is not known whether diabetics have a more pronounced postprandial hypertriglyceridemia than obese subjects. Daylong triglyceridemia, representing postprandial lipemia, was determined in obese subjects with and without type 2 diabetes and in lean subjects. Nineteen type 2 diabetics (F/M: 7/12, body mass index [BMI]: 30.6 +/- 5.4 kg/m(2)), 45 obese nondiabetics (F/M: 16/29, BMI: 29.5 +/- 2.6 kg/m(2)) and 78 lean subjects (F/M: 28/50, BMI: 23.7 +/- 2.2 kg/m(2)) measured capillary triglycerides (TGc) during 3 days on 6 fixed time-points each day in an out-of-hospital situation. Daylong TGc profiles were calculated as mean integrated area under the TGc-curve (TGc-AUC). Fasting plasma TG were higher in diabetics and obese nondiabetics (1.81 +/- 0.79 and 1.77 +/- 0.80 mmol/L) compared with lean subjects (1.23 +/- 0.67 mmol/L, P <.001). TGc-AUC was similarly increased in both diabetics and obese nondiabetics (35.0 +/- 12.1 and 35.2 +/- 10.6 mmol.1 h/L) compared with lean controls (25.5 +/- 12.0 mmol.1 h/L, P <.001). Self-reported energy intake was not significantly different between the groups. Fasting TGc (r =.87, P <.001) and waist circumference (r =.51, P <.001) were the parameters best associated with TGc-AUC. Using stepwise multiple regression analysis, fasting TGc, BMI, total cholesterol, and high-density lipoprotein (HDL) cholesterol were the best predictors of TGc-AUC, explaining 77% of the variation. The cut-off level for "normal" TGc-AUC, calculated as the 75th percentile of TGc-AUC in lean subjects, was 30.7 mmol.1 h/L and corresponded with a fasting TGc of 1.8 mmol/L (eg, 1.6 mmol/L in plasma), calculated using univariate regression analysis. In conclusion, daylong triglyceridemia is similarly increased in diabetics and obese nondiabetics compared with lean subjects. Fasting TG and central obesity largely determine daylong triglyceridemia, independent of the presence of type 2 diabetes. Decreasing fasting plasma TG below 1.6 mmol/L could lead to a normalization of postprandial lipemia in obese subjects with and without diabetes.     

Diagnostic criteria for diabetes mellitus and other categories of glucose intolerance: 1997 criteria by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (ADA), 1998 WHO consultation criteria, and 1985 WHO criteria. World Health Organization.

To compare 1997 ADA diagnostic criteria for diabetes mellitus and other categories of glucose intolerance/1998 WHO Consultation criteria versus 1985 WHO criteria, we analyzed data from a 75-g oral glucose tolerance test (OGTT) performed on 1051 high-risk subjects without medical history of diabetes at Diabetes Screening Clinic, Ramathibodi Hospital, Thailand. There were 372 males and 679 females, aged (mean +/- S.D.) = 50.3 +/- 12.55 years, BMI = 25.62 +/- 4.39 kg/m2. If fasting plasma glucose (FPG) was used as recently recommended then 54.1, 20.4, and 25.5% of cases were classified as normal, impaired fasting glucose (IFG), and diabetic, respectively. In diagnosing diabetes using a full OGTT based on the 1985 WHO criteria as the reference test, FPG > or = 7 mmol/l had a sensitivity of 57.7%, specificity of 97.4%, positive predictive value of 94.0%, and negative predictive value of 76.4%; 53.7% of subjects with IFG had 2-h plasma glucose > or = 11.1 mmol/l. The 1997 ADA/1998 WHO Consultation criteria and 1985 WHO criteria for a full OGTT yield similar overall results. FPG ( > or = 7 mmol/l) was not sensitive for diagnosing diabetes. Moreover, about half of the subjects with IFG were actually diabetic. Therefore, OGTT remains a valuable test in diagnosing diabetes and classifying various categories of glucose intolerance.     

空腹血糖受损切点变化与糖尿病及心脑血管事件风险的关系--上海华阳社区40岁以上人群的随访研究

目的　比较 1999年世界卫生组织 (WHO)及 2 0 0 3年美国糖尿病协会 (ADA)标准诊断的空腹血糖受损 (IFG)与糖尿病和心脑血管事件发生风险的关系 ,从而探讨中国人IFG切点下调的合理性。方法　对 1999年上海华阳社区 40岁以上代谢综合征及其相关疾病 (糖尿病、高血压、肥胖、血脂紊乱 )的横断面调查人群在 2 0 0 2～ 2 0 0 4年进行随访。随访对象接受了 75g葡萄糖耐量试验 ,并检测血糖、血脂、胰岛素、血压、体重指数、腰围与腰臀比等。调查了心脑血管事件发生情况。结果　 (1)基线资料中无糖尿病人群共170 4例 ,完成随访 12 92例。 3年糖尿病累积发生率为 4.64 % ,年发病率 1.5 5 %。 (2 )正常糖调节及糖调节受损人群的糖尿病年发病率分别为 0 .97%及 6.97%。 (3 )随访空腹血糖 (FPG) 5 .6～ 6.0mmol/L、6.1～ 6.9mmol/L而餐后 2h血糖 (2hPG) <7.8mmol/L的人群见到发生糖尿病的风险分别增加 3 .71及 2 8.12倍 (P <0 .0 0 1) ,但未见到发生心脑血管事件的风险显著增加。 (4 )在FPG <5 .6mmol/L且 2hPG 7.8～ 11.0mmol/L人群中 ,发生糖尿病及心脑血管事件的相对风险分别显著增加 4.3 1及 3 .40倍 (P <0 .0 0 1)。结论　FPG 5 .6～ 6.0mmol/L的人群发生糖尿病的风险显著增加 ,将空腹血糖受损的下限调整至 5 .     

Diminution of early insulin response to glucose in subjects with normal but minimally elevated fasting plasma glucose. Evidence for early beta-cell dysfunction.

AIM: Systematic analysis of beta-cell function in Japanese health examinees. METHODS: In 938 Japanese health examinees (627 men and 311 women, mean age and body mass index, 54.0 years and 23.6 kg/m2, respectively), plasma specific insulin was measured at fasting and during a 75-g oral glucose tolerance test. The subjects were stratified into six groups based on fasting plasma glucose < or = 5.1 mmol/l, 5.2-6.0 mmol/l, 6.1-6.9 mmol/l, 7.0-7.8 mmol/l, 7.9-8.7 mmol/l, and > or = 8.8 mmol/l as the 1st, 2nd, 3rd, 4th, 5th and 6th groups, respectively. RESULTS: Distribution of fasting insulin showed a very modest 'inverted U' shape, with the peak in the 5th group. Progressive increase from the 1st toward the 5th group was significant. In contrast, the ratio of change in insulin to change in glucose from 0 to 30 min during the glucose tolerance test was greatest in the 1st group and progressively declined in the groups with higher fasting glycaemia. Difference in the ratio was most striking and highly significant between the 1st and 2nd groups. Distribution of the insulin to glucose ratio of subjects with normal glucose tolerance significantly overlapped with that of untreated patients with diabetes. CONCLUSIONS: In a Japanese population, (i) beta-cell starts to deteriorate during normoglycaemia with a minimal elevation of fasting plasma glucose, and (ii) there are glucose-tolerant subjects with beta-cell dysfunction.     

空腹血糖水平与胰岛素抵抗的关系

目的探讨美国糖尿病协会2003年修订的空腹血糖受损(IFG)下限新切点(5·6mmol/L)划分出的中国血糖调节异常(IGR)者是否存在胰岛素抵抗。方法选取糖调节正常者(NGR)9例;以新标准划分的单纯IFG者9例;空腹及糖负荷后血糖均异常的糖调节受损者共20例,其中以新空腹血糖(FPG)切点划分的新联合糖耐量低减(IGT)者10例;以旧FPG切点划分的旧联合IGT者10例;2型糖尿病患者10例。以高胰岛素正葡萄糖钳夹技术测定受试对象的胰岛素敏感性,以静脉葡萄糖耐量试验评估其胰岛β细胞分泌功能。结果(1)新单纯IFG组、新联合IGT组和旧联合IGT组的葡萄糖输注率(GIR)[分别为(7·2±0·8、7·0±1·5、4·8±0·4)mg·kg-1·min-1]明显低于NGR组[(10·3±0·9)mg·kg-1·min-1,P值均<0·05];旧IGT组和DM组[(5·6±1·0)mg·kg-1·min-1]处于相近水平。(2)空腹胰岛素水平在所有IGR组均升高,在DM组下降。(3)新IFG组的胰岛素一、二相分泌量和NGR组相似,但随糖代谢紊乱程度加重,胰岛素一相分泌量进行性下降,而二相分泌水平先逐渐升高,后有所降低。结论(1)新空腹血糖切点划分出的中国IGR者已经出现胰岛素抵抗。(2)随糖代谢紊乱程度的加重,胰岛素分泌缺陷趋于明显。     

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

OBJECTIVE: To evaluate insulin resistance (IR), beta-cell function, and glucose tolerance in 119 Brazilian adolescents with obesity or risk factors (RF) for type 2 diabetes mellitus (T2DM). STUDY DESIGN: We analyzed weight (kg), height (m), body mass index (BMI; kg/m(2)), waist (W; cm), acanthosis nigricans (AN), systolic and diastolic blood pressure (SBP and DBP; mm Hg), fasting plasma glucose (FPG), and 2-h plasma glucose (2hPG) on oral glucose tolerance test (OGTT; 1.75 g of glucose/weight), lipid profile [total cholesterol (TC), fractions, and triglycerides (TGs)], fasting insulin (FI) and 2-h insulin on OGTT (2hI-RIA), HOMA-B (%; beta-cell function--HOMA program), HOMA-S (%; insulin sensitivity--HOMA program) and HOMA-IR [fasting plasma insulin (mU/ml)xfasting plasma glucose (mmol/L)/22.5]. Division according to number of RF-family history of T2DM (FHT2DM), obesity, hypertension, dyslipidemia, polycystic ovary syndrome (PCOS), and AN. G1: subjects with no or one RF; G2: subjects with two or more RFs. Statistical data were nonparametrical. RESULTS: Fasting plasma glucose (G2: 81.6+/-10.2 vs. G1: 79.8+/-9.9 mg/dl) and 2hPG (88.1+/-18.0 vs. 87.0+/-19.9 mg/dl) were not different between G2 (n=67) and G1 (n=52), and all adolescents had normal glucose tolerance (NGT). Fasting insulin (13.0+/-7.9 vs. 7.6+/-3.9 microIU/ml; P<.001) and 2hI (60.2+/-39.1 vs. 38.3+/-40.0 microIU/ml; P<.001), HOMA-B (169.1+/-131.6% vs. 106.1+/-39.9%; P<.001), and HOMA-IR (2.62+/-1.7 vs. 1.52+/-0.8; P<.001) were higher in G2. HOMA-S (92.5+/-59.5% vs. 152.2+/-100.5%; P<.001) was also lower in this latter group. CONCLUSION: Brazilian adolescents with two or more RFs for the development of T2DM have higher IR and beta-cell function and lower insulin sensitivity. However, adolescents with impaired glucose tolerance (IGT) or DM have not been found, differently from similar studies. Differences in ethnic background, environment, and lifestyle factors may account for this disparity.     

Rosiglitazone taken once daily provides effective glycaemic control in patients with Type 2 diabetes mellitus.

AIMS: To evaluate the clinical efficacy and safety of rosiglitazone as a once daily treatment for Type 2 diabetes mellitus (DM). METHODS: Three hundred and sixty-nine patients with Type 2 DM (mean age 63 years; mean body mass index (BMI) 29.4 kg/m2) were enrolled in a double-blind, parallel group, placebo-controlled, dose-ranging study. Patients were randomly assigned to receive placebo or rosiglitazone at doses of 4, 8, or 12 mg daily for 8 weeks. RESULTS: At 8 weeks, fasting plasma glucose (FPG) decreased significantly in the rosiglitazone 4 mg, 8 mg, and 12 mg groups (-0.9, -2.0 and -1.7 mmol/l; P = 0.0003, < 0.0001, and < 0.0001, respectively) compared with placebo (+0.4 mmol/l). The improvements in FPG were dose ordered for 4 and 8 mg/ day. The 12 mg/day dose produced no additional improvement. There were small decreases in haemoglobin and haematocrit in the rosiglitazone treatment groups. The overall incidence of adverse experiences was similar in all treatment groups, including placebo with no evidence of hypoglycaemia or hepatotoxicity. CONCLUSIONS: Rosiglitazone improves glycaemic control when given once daily to treat Type 2 diabetes mellitus and is well tolerated at doses up to and including 12 mg.     

Decrement of postprandial insulin secretion determines the progressive nature of type-2 diabetes

OBJECTIVE: Type-2 diabetes is a progressive disease. However, little is known about whether decreased fasting or postprandial pancreatic beta-cell responsiveness is more prominent with increased duration of diabetes. The aim of this study was to evaluate the relationship between insulin secretion both during fasting and 2 h postprandial, and the duration of diabetes in type-2 diabetic patients. DESIGN: Cross-sectional clinical investigation. METHODS: We conducted a meal tolerance test in 1466 type-2 diabetic patients and calculated fasting (M0) and postprandial (M1) beta-cell responsiveness. RESULTS: The fasting C-peptide, postprandial C-peptide, M0, and M1 values were lower, but HbA1c values were higher, in patients with diabetes duration > 10 years than those in other groups. There was no difference in the HbA1c levels according to the tertiles of their fasting C-peptide level. However, in a group of patients with highest postprandial C-peptide tertile, the HbA1c values were significantly lower than those in other groups. After adjustment of age, sex, and body mass index (BMI), the duration of diabetes was found to be negatively correlated with fasting C-peptide (gamma = -0.102), postprandial C-peptide (gamma = -0.356), M0 (gamma = -0.263), and M1 (gamma = -0.315; P < 0.01 respectively). After adjustment of age, sex, and BMI, HbA1c was found to be negatively correlated with postprandial C-peptide (gamma = -0.264), M(0) (gamma = -0.379), and M1 (gamma = -0.522), however, positively correlated with fasting C-peptide (gamma = 0.105; P < 0.01 respectively). In stepwise multiple regression analysis, M0, M1, and homeostasis model assessment for insulin resistance (HOMA-IR) emerged as predictors of HbAlc after adjustment for age, sex, and BMI (R2 = 0.272, 0.080, and 0.056 respectively). CONCLUSIONS: With increasing duration of diabetes, the decrease of postprandial insulin secretion is becoming more prominent, and postprandial beta-cell responsiveness may be a more important determinant for glycemic control than fasting beta-cell responsiveness.     

Polymorphism Ncol in tumor necrosis factor B is associated with fasting glycemia and lipid parameters in healthy non-obese caucasian subjects

BACKGROUND: The study was designed to investigate the associations among polymorphisms TNF-B Ncol and TNF-alpha -308G/A, plasma TNF-alpha levels and metabolic and anthropometric parameters related to insulin sensitivity in a set of 113 Caucasian subjects undergoing oral glucose tolerance test (oGTT). METHODS: Genotypes were detected by PCR; BMI, WHR, glycemia during oGTT, fasting immunoreactive insulin, fasting C-peptide, HbA(1c), total cholesterol, triglycerides, HDL, LDL and plasma TNF-alpha levels were measured in each subject. RESULTS: Type 2 diabetes was diagnosed in 10 subjects, impaired glucose tolerance (IGT) in 41, normal glucose tolerance (NGT) in 62. Significant differences among genotypes of the TNF-B Ncol were observed for FPG (P=0.0063), LDL (P=0.0179) and marginally for total cholesterol (P=0.0763) in NGT group. After the classification of NGT subjects into obese and non-obese according to BMI, associations of TNF-B Ncol with FPG, LDL and cholesterol were proved in non-obese subgroup only. TNF-alpha -308G/A polymorphism was not associated with any of the parameters studied. TNF-alpha levels did not revealed difference among NGT, IGT and DM groups or genotype-dependent differences. CONCLUSIONS: Our results indicate significant association of the TNF-B Ncol polymorphism with FPG, LDL and total cholesterol in normoglycemic non-obese Caucasian subjects. This polymorphism could be involved in genetic modulation of glucose and lipid homeostasis and regulation of insulin sensitivity already in healthy state. Disturbances of this regulation could be component of pathogenesis of type 2 diabetes mellitus.     

Nine weeks of bedtime diazoxide is well tolerated and improves beta-cell function in subjects with Type 2 diabetes.

AIMS: To test whether a bedtime dose of diazoxide can improve daytime beta-cell function without side-effects in Type 2 diabetes. METHODS: A double-blind randomized study was performed in 27 Type 2 diabetic subjects (17 male, 10 female) who were treated with bedtime insulin and metformin. Subjects received either bedtime diazoxide, 100 mg, or placebo for 9 weeks. Duplicate C-peptide glucagon tests were performed before and in the last days of intervention. RESULTS: No side-effects of diazoxide were detected. Treatment with diazoxide did not incur any increase in bedtime insulin. C-peptide responses to glucagon tended to increase: 0.15 +/- 0.06 nmol/l vs. -0.01 +/- 0.04 nmol/l for placebo, P < 0.06 for difference. Corresponding effects on insulin were 66.2 +/- 41.7 pmol/l for diazoxide vs. -84.2 +/- 51.5 for placebo, P < 0.03. Treatment with diazoxide decreased fasting glucagon levels by 41% vs. placebo, P < 0.03. Glycated haemoglobin (HbA1c) levels were not affected, whereas levels of blood glucose post breakfast were higher during diazoxide (1.34 +/- 0.43 mmol/l, P < 0.01 vs. placebo). CONCLUSIONS: Bedtime treatment with diazoxide in Type 2 diabetic subjects on bedtime insulin and metformin has no significant side-effects, does not increase bedtime insulin supplementation, tends to ameliorate beta-cell function but fails to improve metabolic control.     

The effect of gliclazide on plasma insulin, intact and 32/33 split proinsulin in South Asian subjects with Type 2 diabetes mellitus.

AIMS: Previous studies have shown that in Caucasian subjects with Type 2 diabetes mellitus (DM), the sulphonylurea glibenclamide increased insulin secretion without causing an increase in 32/33 split proinsulin secretion. South Asian subjects with Type 2 DM are thought to be more insulin resistant and the effect of sulphonylureas may be different. We therefore investigated the effect of sulphonylurea therapy with gliclazide on beta-cell function in South Asian subjects with newly diagnosed Type 2 DM. METHODS: Glucose, insulin, and intact and 32/33 split proinsulin were measured at diagnostic oral glucose tolerance test (OGTT). After 8-12 weeks on a conventional diet, subjects with a fasting glucose > 6 mmol/l (n = 16) were commenced on gliclazide. RESULTS: At diagnosis, those requiring gliclazide were more hyperglycaemic but there was no difference in weight or fasting insulin concentration than in the diet group. Following diet, in the gliclazide group, weight fell (P < 0.04) with no change in fasting glucose concentration. Fasting intact proinsulin, insulin and 32/33 split proinsulin remained unchanged. After gliclazide therapy weight remained unchanged, but fasting glucose fell (P < 0.003). Fasting insulin and intact proinsulin remained unchanged but 32/33 split proinsulin fell (P < 0.05). Fasting insulin to glucose ratio significantly improved after gliclazide (P < 0.006). CONCLUSIONS: In South Asian subjects treated with gliclazide the reduction in fasting glucose concentrations appears to be due to an improvement in insulin sensitivity as well as in beta-cell function.