The threshold value for identifying insulin resistance (HOMA-IR) in an admixed adolescent population: A hyperglycemic clamp validated study

ABSTRACT Objectives: To validate the homeostasis model assessment (HOMA) of insulin resistance (IR) as a surrogate to the hyperglycemic clamp to measure IR in both pubertal and postpubertal adolescents, and determine the HOMA-IR cutoff values for detecting IR in both pubertal stages. Subjects and methods: The study sample comprised 80 adolescents of both sexes (aged 10-18 years; 37 pubertal), in which IR was assessed with the HOMA-IR and the hyperglycemic clamp. Results: In the multivariable linear regression analysis, adjusted for sex, age, and waist circumference, the HOMA-IR was independently and negatively associated with the clamp-derived insulin sensitivity index in both pubertal (unstandardized coefficient - B = −0.087, 95% confidence interval [CI] = −0.135 to −0.040) and postpubertal (B = −0.101, 95% CI, −0.145 to −0.058) adolescents. Bland-Altman plots showed agreement between the predicted insulin sensitivity index and measured clamp-derived insulin sensitivity index in both pubertal stages (mean = −0.00 for pubertal and postpubertal); all P > 0.05. The HOMA-IR showed a good discriminatory power for detecting IR with an area under the receiver operator characteristic curve of 0.870 (95% CI, 0.718-0.957) in pubertal and 0.861 (95% CI, 0.721-0.947) in postpubertal adolescents; all P < 0.001. The optimal cutoff values of the HOMA-IR for detecting IR were > 3.22 (sensitivity, 85.7; 95% CI, 57.2-98.2; specificity, 82.6; 95% CI, 61.2-95.0) for pubertal and > 2.91 (sensitivity, 63.6; 95% CI, 30.8-89.1, specificity, 93.7; 95%CI, 79.2-99.2) for postpubertal adolescents. Conclusion: The threshold value of the HOMA-IR for identifying insulin resistance was > 3.22 for pubertal and > 2.91 for postpubertal adolescents.

Pharmacokinetics, pharmacodynamics, and bioequivalence study of SciLin TMR recombinant human insulin injection preparation / 中华临床营养杂志

Objective To study the pharmacokinetics and pharmacodynamics of recombinant human insulin preparations SciLin TM R and Humulin (R) R,and to evaluate their bioequivalence in Chinese healthy volunteers.Methods In this positive control,single dose,open label,randomized cross-over study,20 male healthy volunteers were recruited from March to October 2007,and tested on two experimental days with an interval of 7-14 days.The volunteers were divided into two groups with a random number table,one group was injected with SciLin TMR for the first time and Humulin (R) R for the second time,the other group was injected with the opposite.The pharmacokinetics and pharmacodynamic properties were evaluated by euglycemic glucose clamp study.Results Time to peak concentration [Tmax,(105.8 ± 19.1) minutes vs.(103.5 ± 18.1) minutes,P =0.389) and time to maximum glucose infusion rate [TGIRmax,(132.8 ± 16.8) minutes vs.(132.8 ± 18.6) minutes,P =0.697] for SciLin TMR and Humulin(R) R were similar.The relative bioavailability of SciLin TMR was (102.2 ± 7.6) ％,and the relative biological effectiveness was (107.4 ± 18.8) ％.The 90％ confidence interval(CI) of peak concentration(Cmax) and area under the curve of blood glucose concentration at 0-10 hours (AUCIns 0-10) of SciLin TM R were 99.32 ％-102.62 ％ (equivalent range 70％-143 ％) and 98.98 ％-104.99 ％ (equivalent range 80％-125％),respectively;90％ CI of the maximum glucose infusion rate (GIRmax) and AUCGIR0-10 were 97.36％ ～ 103.49％ (equivalent range 70％-143％) and 98.72％-113.54％ (equivalent range 80％-125％),respectively,indicating that SciLin TMR and Humulin (R) R was bioequivalent.There was no clinically significant abnormalities in the safety indexes before and after the tests.During the trial,no hypoglycemic events,allergic reactions,or local injection adverse reaction occurred.Conclusion The studied recombinant human insulin preparation SciLin TMR may be bioequivalent as Humulin (R) R.

Pharmacokinetics and pharmacodynamics of 40/60 premixed recombinant human insulin injection preparations / 中华临床营养杂志

Objective To study the pharmacokinetics and pharmacodynamics of the 40/60 premixed recombinant human insulin injection preparation,and to compare with 30/70 preparation,regular insulin,and neutral protamine Hagedorn (NPH).Methods In this positive control,single dose,open label,Latin square crossover study,20 male healthy volunteers were recruited from May 2006 to March 2007,and divided into four groups.On 4 test days,40/60 preparation,30/70 preparation,regular insulin,and NPH were administered to each of the 4 groups,the interval was 7-70 days before 2 test days.The pharmacokinetics and pharmacodynamics were evaluated by euglycemic glucose clamp technique.Results According to the analysis of variance,there were statistically significant differences in pharmacokinetics and pharmacodynamics of the 4 insulin formulations between the 4 groups (all P ＜ 0.05).For the 40/60 premixed recombinant human insulin,the pharmacokinetic parameter time to peak (Tmax) and mean retention time (MRT) were (105.00 ±24.33) minutes and (321.77 ± 56.29) minutes,respectively;the glucose-lowering effects reflected by the pharmacodynamic parameter Tmax and MRT were (167.75 ± 26.48) minutes and (248.33 ± 14.96) minutes,respectively.Compared with 30/70 premixed recombinant human insulin,40/60 preparation showed no significant differences in the pharmacokinetics parameters of blood insulin concentration,including peak concentration [(91.67 ± 13.03) mU/L vs.(84.96 ± 14.75) mU/L,P =0.119],Tmax [(105.00 ± 24.33) minutes vs.(122.25 ± 39.35) minutes,P =0.128],MRT [(321.77 ± 56.29) minutes vs.(332.12 ± 49.20) minutes,P =0.645] and area under the curve in 0-16 hours [AUCIns 0-16,(24 918 ± 6 610)h · mU/L vs.(26 768 ± 8 032)h· mU/L,P=0.084];however,statistically significant differences were observed in AUCIns0-4 [(16 991 ± 3 673) h · mU/L vs.(12 407 ± 3 441) h · mU/L,P =0.042] and AUCIns 0-8 [(23 283 ± 4 939) h · mU/L vs.(19 397 ±5 314)h · mU/L,P =0.046].Pharmacodynamic parameters showed no statistically significant differences (all P ＞ 0.05).Compared with 30/70 premixed insulin,the relative bioavailability of 40/60 premixed insulin was (118.9 ± 35.9) ％,and the relative biological effectiveness was (106.6 ± 35.2) ％.There was no clinically significant abnormalities in the safety indexes before and after the tests.No hypoglycemic events,allergic reactions,or local injection adverse reaction occurred in this trial.Conclusions The 40/60 premixed recombinant human insulin preparation demonstrated different properties in insulin absorption in 8 hours after injection compared with the 30/70 preparation,mainly because of the difference in proportions of short-and intermediate-acting insulin in the mixture.This new premixed insulin may provide a new option for personalized diabetes management.

Methods for the Assessment of Insulin Resistance / 임상당뇨병

Insulin resistance is one of the major aggravating factors for metabolic disease. There are many methods available for estimation of insulin resistance which range from complex techniques down to simple indices. For all methods of assessing insulin resistance, it is essential that their validity and reliability be established before using them in clinical investigations. The reference techniques of hyperinsulinemic euglycemic clamp and its alternative,the frequently sampled intravenous glucose tolerance test, are the most reliable methods available for estimating insulin resistance. However, there are many simple methods from which indices can be derived that have been assessed and validated, which include homeostasis model assessment (HOMA) and the quantitative insulin sensitivity check index (QUICKI). Given the increasing number of simple indices of insulin resistance, it may be difficult for clinicians and researchers to select the most appropriate index for their studies. In planning studies on insulin resistance and selecting a suitable index, a number of important factors need to be considered by investigators, the principle one being the nature of the study to be undertaken.

O envelhecimento do pâncreas endócrino: fisiopatologia de diabetes mellitus tipo 2 e a caracterização da incretinopatia com início na senectude / The aging of endocrine pancreas: physiopathology of diabetes mellitus type 2 and characterization of incretinpathy starting on senescence

Objetivo: Estimar o impacto do envelhecimento e do diabetes na sensibilidade à insulina, função da célula beta, adipocitocinas e produção de incretina Métodos: Foram realizados clamps hiperglicêmicos, testes de arginina e testes de refeição padrão em 50 pacientes não obesos para medir a sensibilidade à insulina e secreção de insulina, assim como os níveis plasmáticos do glucagon, GLP-1 e GIP. Os pacientes com diabetes e do grupo controle saudáveis foram divididos nos seguintes grupos: meia idade com diabetes tipo 2 (MI-DM2), idosos com diabetes tipo 2 (I-DM2), meia idade ou idosos com tolerância normal à glicose (MI-TNG, I-TNG). Resultados: A sensibilidade à insulina (SI), determinada pelo modelo de avaliação da homeostase, taxa de infusão de glicose e pela sensibilidade à insulina a glicose oral, foi reduzida no grupo de idosos e nos grupos com DM2, comparados com o grupo de meia idade com tolerância normal à glicose, mas foi similar no grupo MI-DM2 e grupo I-DM2. O índice insulinogênico, a primeira e segunda fase de secreção de insulina e o índice de disposição, com exceção da resposta da insulina à arginina, foram reduzidos com o envelhecimento e nos grupos com DM2. A produção pós-prandial média de glucagon no tempo total de 0 - 180 minutos foram maiores no grupo de DM2 comparado ao grupo de TNG, sendo que na primeira hora da produção de glugagon o grupo de I-DM2 apresentou uma média mais elevado em relação ao grupo de MI-DM2. Embora a produção de GLP-1 tenha sido reduzida no grupo I-DM2, nenhuma diferença entre os grupos foi observada em relação à produção de GIP. Conclusão: O diabetes e o envelhecimento desencadearam uma redução da sensibilidade à insulina em pacientes não obesos. A produção de insulina foi reduzida com o envelhecimento e exacerbada pela condição do diabetes. As deficiências associadas ao envelhecimento se sobrepõe a fisiopatologia do diabetes, particularmente relacionada à produção de GLP-1...

Objective: To estimate the impact of aging and diabetes on insulin sensitivity, beta-cell function, adipocytokines, and incretin production. Methods: Hyperglycemic clamps, arginine tests and meal tolerance tests were performed in 50 non-obese subjects to measure insulin sensitivity (IS) and insulin secretion as well as plasma levels of glucagon, GLP-1 and GIP. Patients with diabetes and healthy control subjects were divided into the following groups: middle-aged type 2 diabetes (MA-DM), elderly Type 2 diabetes (E-DM) and middle-aged or elderly subjects with normal glucose tolerance (MA-NGT or E-NGT). Results: IS (insulin sensitivity), as determined by the homeostasis model assessment glucose infusion rate and oral glucose insulin sensitivity, was reduced in the aged and DM groups compared with MA-NGT, but similar in MA-DM and E-DM groups. Insulinogenic index, first and second phase of insulin secretion and the disposition indices, except insulin response to arginine, were reduced in the elderly and DM groups. The average postprandial glucagon production on the interval of 0-180 min was higher in DM groups compared to NGT groups, furthermore noticed that in the first hour of glucagon secretion, group E-DM had a higher average value compared to group MA-DM. Whereas the GLP-1 production was reduced in A-DM, no differences between groups were observed in GIP production. Conclusions: In non-obese subjects, diabetes and aging impair insulin sensitivity. Insulin production is reduced by aging, and diabetes exacerbates this condition. Aging associated defects superimposed diabetic physiopathology, particularly regarding GLP-1 production. On the other hand, the glucose-independent secretion of insulin was preserved. The knowledge of the complex relationship between aging and diabetes could support the development of physiopathological and pharmacological based therapies.

The application of glucose damp technique on the children endocrine field / 国际儿科学杂志

Insulin sensitivity and insulin secretion function are the hot spots for studying the sugar and lipid metabolism. Hyperinsulinemic euglycemic clamp and hyperglycemic clamp are the gold standard for insulin sensitivity test and insulin secretion function test. Lack of insulin secretion and insulin resistance are the two main pathogenesis of diabetes. Adopting glucose clamp technology to explore diabetes and diabetic complications, and other endocrine diseases has bocome the main method. Recently,this technology has been initially used in childhood diabetes,obesity, short stature syndrome, metabolic syndrome, et al. Hie technology becomes common in children with endocrine diseases.

Overcoming metabolic syndrome in severe obesity: adiponectin as a marker of insulin sensitivity and HDL-cholesterol improvements after gastric bypass / Reversão da síndrome metabólica na obesidade mórbida: adiponectina como um marcador da sensibilização à insulina e do aumento do HDL-colesterol após o bypass gástrico

OBJECTIVE: To assess the relationship between adiponectin and metabolic parameters in severely obese women during surgical-induced weight loss. METHODS: Nineteen lean (CT - BMI:21.2 ± 0.3 kg.m²), 14 overweight/class II obese (OB/OW - BMI: 29.7 ± 0.7 kg/m²) and 8 morbidly obese (OBIII - BMI: 56.4 ± 3.6 kg/m²) were evaluated by hyperinsulinemic-euglycemic clamp, adiponectin, and lipids. OBIII were evaluated at 5th and 16th month post-operatively. RESULTS: Compared to lean, obese groups had lower adiponectin (OB/OW: 9.4 ± 0.9, OBIII: 7.1 ± 1.3 versus 12.2 ± 0.9 ng/dL; p < 0.01), lower HDL-cholesterol (OB/OW:1.05 ± 0.05, OBIII: 0.88 ± 0.04 versus 1.22 ± 0.07 mmol/L; p < 0.01) and insulin resistance-IR (glucose uptake, M-value - OB/OW: 43.6 ± 2.7, OBIII: 32.4 ± 3.2 versus 20.0 ± 1.8 umol/kgFFM.min; p < 0.001). Considering all subjects, adiponectin levels were inversely correlated to BMI and waist circumference, and directly to M-value and HDL-cholesterol (p < 0.01). During weight loss, improvements in IR (Study III: 36.1 ± 3.9 umol/kg/FFM.min, p < 0.0001), adiponectin (11.8 ± 1.4 ng/dL, p = 0.006) and HDL-cholesterol were observed (1.10 ± 0.04 mmol/L, p = 0.007). Moreover, HDL-cholesterol improvement was significantly and independently related to variations of adiponectin and BMI (r² = 0.86; p < 0.0002). CONCLUSIONS: The improvements of IR and adiponectin were related to surgical-induced weight loss, suggesting an important role of adiponectin in HDL-cholesterol regulation.

OBJETIVO: Identificar a relação entre adiponectina e parâmetros metabólicos em mulheres obesas mórbidas durante o emagrecimento por bypass gástrico. MÉTODOS: Dezenove magras (CT - IMC: 21,2 ± 0,3 kg/m²), 14 com sobrepeso/obesidade classe II (OB/OW - IMC: 29,7 ± 0,7 kg/m²) e oito obesas classe III (OBIII - IMC:56,4 ± 3,6 kg/m²) foram avaliadas pelo clamp euglicêmico-hiperinsulinêmico, adiponectina e lípides. OBIII submeteram-se aos mesmos testes no quinto e décimo-sexto mês pós-operatório. RESULTADOS: comparados a CT, os grupos obesos tiveram menor adiponectinemia (OB/OW: 9,4 ± 0,9, OBIII: 7,1 ± 1,3 versus 12,2 ± 0,9 ng/dL; p < 0,01), menor HDL-colesterol (OB/OW: 1,05 ± 0,05, OBIII: 0,88 ± 0,04 versus 1,22 ± 0,07 mmol/L; p < 0,01) e resistência insulínica - RI (captação de glicose, M - OB/OW:43,6 ± 2,7, OBIII:32,4 ± 3,2 versus 20,0 ± 1,8 umol/kgFFM.min; p < 0,001). Analisando todos os voluntários: adiponectina correlacionou-se negativamente com IMC, circunferência da cintura e positivamente ao M-clamp e HDL-colesterol (p < 0,01). No emagrecimento, houve melhora da RI (Estudo III:36,1 ± 3,9 umol/kgFFM.min, p < 0,0001), adiponectina (11,8 ± 1,4 ng/dL, p = 0,006) e HDL-colesterol (1,10 ± 0,04 mmol/L, p = 0,007). Aumentos do HDL-colesterol foram significativa e independentemente relacionados às variações da adiponectina e IMC (r² = 0,86; p < 0,0002). CONCLUSÕES: A melhora da RI e adiponectina no emagrecimento induzido por bypass gástrico sugerem um importante papel da adiponectina na regulação do HDL-colesterol.

Establishment of hyperinsulinemic euglycemic clamp technique and the reference value of insulin sensitivity index in Chinese / 中华临床营养杂志

Objective To establish the technique of hyperinsulinemic euglycemic clamp and to study the reference value of insulin sensitivity index in healthy Chinese. Methods According to the feedback mathematical model developed by DeFronzo, the technique of hyperinsulinemic euglycemic clamp was used in 90 healthy Chi- nese [ male:female =71 = 19; age; (28. 3±6. 1) years; body mass index (20. 9±1.5) kg/m2 ] to study die glu-cose metabolized rate. Blood samples were obtained at timed intervals in the fasting state and during the clamp for the measurement of glucose, insulin and C peptide. Results During the clamp tests, the blood glucose levels were con-trolled within 10% of target value. The coefficient of variation of glucose levels was 3. 8% 0.1%. In the steady state, the insulin sensitivity index (glucose metabolized rate, M value ) was (7.78±2.30) mg· kg-1 min-1, which was distributed normally. The lowest quartile of M value was 6. 286 mg·kg -1 min-1'. The coefficient of variation of M value was 9.4%±2.8%. Conclusion The technique of hyperinsulinemic euglycemic clamp and the reference value of insulin sensitivity index in healthy Chinese are successfully established in our center.

Marked Suppression of Ghrelin Concentration by Insulin in Prader-Willi Syndrome

The plasma ghrelin has been reported to be elevated in Prader-Willi syndrome (PWS) and modulated by insulin. It was hypothesized that insulin might have a more pronounced effect on reducing plasma ghrelin in PWS patients, which would influence appetite. This study investigated the degree of ghrelin suppression using an euglycemic hyperinsulinemic clamp in children with PWS (n=6) and normal children (n=6). After a 90-min infusion of insulin, the plasma ghrelin level decreased from a basal value of 0.86+/-0.15 to 0.58+/-0.12 ng/mL in the controls, and from 2.38+/-0.76 to 1.12+/-0.29 ng/mL in children with PWS (p=0.011). The area under the curve below the baseline level over the 90 min insulin infusion was larger in children with PWS than in controls (-92.82+/-44.4 vs. -10.41+/-2.87 ng/mL/90 min) (p=0.011). The insulin sensitivity measured as the glucose infusion rate at steady state was similar in the two groups (p=0.088). The decrease in the ghrelin levels in response to insulin was more pronounced in the children with PWS than in the controls. However, the level of ghrelin was always higher in the children with PWS during the clamp study. This suggests that even though insulin sensitivity to ghrelin is well maintained, an increase in the baseline ghrelin levels is characteristic of PWS.

Effect of Rhizoma Coptidis apozem on expression of AMP-activated protein kinase in skeletal muscle of metabolic syndrome rats / 中华中医药杂志

Objective:To study the effect of Rhizoma Coptidis apozem on expression of AMP-activated protein kinase(AMPK) in skeletal muscle of metabolic syndrome rats. Methods:The models were established by administering high fat diet. Rats were randomly divided into five group: normal control group, metabriolic syndome group, Rhizoma Coptidis apozem group, Berberine group, Metformin group. To estimate insulin resistance by euglycemic hyperinsulinemic glucose clamp(GC) tecchnique. To estimate expression of AMPK by using Western blot. Results: Compared with metabolic syndrome group, Rhizoma Coptidis apozem group had higher M-value, lower wet weight of innards fat, and higher protein level of p-AMPK-?. Conclusion: Rhizoma Coptidis apozem can improve insulin resistance, decrease innards fat, and regulate up expression of AMPK.

Effect of rosiglitazone on insulin sensitivity and ?-cell function in polycystic ovary syndrome patients with insulin resistance / 第三军医大学学报

Objective To explore the effect of rosiglitazone on the insulin sensitivity and ?-cell function in polycystic ovary syndrome(PCOS)patients accompanied with insulin resistance.Methods Rosiglitazone was given to 15 patients PCOS with insulin resistance at a dose of 4 mg daily for 12 weeks.All patients underwent an oral glucose tolerance test and Botnia clamp,and their body mass index(BMI),waist/hip ratio(WHR),serum pressure,follicle-stimulating hormone(FSH),luteinizing hormone(LH),testosterone,free testosterone(FT),glucose and insulin were determined and compared before and at the end of the treatment.Results After 12 weeks' treatment,Waist/Hip ratio,FT and LH/FSH ratio,and fasting insulin were significantly decreased(P

Establishment of an extended hyperinsulinemic euglycemic clamp technique / 中华内分泌代谢杂志

Objective To establish an extended hyperinsulinemic euglycemic clamp for the study of insulin sensitivity in Chinese. Methods Combining glucose clamp, 3 3H labelled glucose tracer technique and indirect calorimetry, an extended hyperinsulinemic euglycemic clamp technique was applied into the study of methodology in 9 normal weight subjects with normal glucose tolerance. Results (1) When a higher level of insulin was created during maintaining euglycemia, hepatic glucose production was completely inhibited, and the counter regulatory hormones (including cortisol, growth hormone and glucagon) and endogenous insulin secretion were not significantly stimulated. (2) During the steady state of the extended hyperinsulinemic euglycemic clamp, the insulin mediated glucose disappearance rate was significantly increased compared with basal state 〔(5.86?0.65)mg?kg -1 ?min -1 vs (2.45?0.15)mg?kg -1 ?min -1 , P

Study on the relation between insulin resistance and total and regional body fat in overweight and obese individuals / 中华内分泌代谢杂志

Objective To use the extended hyperinsulinemic euglycemic clamp technique for the study of insulin sensitivity in normal weight and normal glucose tolerant obese Chinese, and also, for the study of insulin sensitivity in relation to body adipose depots and distribution. Methods Twenty two Chinese 〔9 with normal weight (BMI

Investigation on pharmacokinetics and bioavailabiUty of insulin dry powder inhalation / 中华内分泌代谢杂志

Objective To study the characteristics of pharmacokinetics and pharmacodynamics of insulin dry powder inhalation and its relative bioavailability as compared with subcutaneous injection of regular insulin. Methods In this open,single-center,randomized,two-period,cross-over,euglycemic glucose clamp study,18 healthy volunteers(14 men and 4 women),aged(24.9?1.7)years,with body mass index(20.6?1.2)kg/m~2, received the insulin dry powder inhalatin(80 U)or regular insulin(15 U)subcutaneous administration.The blood samples of this study at 0,20,30,40,50,60,70,80,90,100,110,120,135,150,165,180,195, 210,225,240,270,300,330,360,390,420,450 and 480 rain were taken for serum insulin measurement, meanwhile,glucose infusion rates(GIR)were determined per 5 minutes over a period of 8 hours.Results The C_(max)were(57.9?17.8 vs 114.5?29.7)mU/L(tested vs reference preparation),T_(max)were(46.7?45.6 vs 107.8?33.7)min,GIR_(max)were(3.35?0.98 vs 5.17?1.75)mg?kg~(-1)?min~(-1)and T_(GIRmax)were(88.3?17.0 vs 151.9?34.6)min.The relative bioavailability was(10.26?2.25)%,and the relative bioefficacy was(14.33?7.26)%.Conclusion The study shows that insulin dry powder inhalation is absorbed via lungs and its action sets in earlier than that of the regular insulin injected subcutaneously.These pharmacokinetie and pharmacodynamic data may provide a reliabe guide for further clinical trial.

Effect of High Fat Diet on Insulin Resistance: Dietary Fat Versus Visceral Fat Mass

The purpose of the present study was to determine whether chronic high-fat diet (HF) induces insulin resistance independently of obesity. We randomly divided 40 rats into two groups and fed them either with a HF or with a high-carbohydrate diet (HC) for 8 weeks. Whole body glucose disappearance rate (Rd) was measured using a euglycemic hyperinsulinemic clamp. Firstly, we defined whether insulin resistance by HF was associated with obesity. Plasma glucose and triglyceride concentrations were significantly increased in HF. Rd was decreased (10.6+/-0.2 vs. 9.1+/-0.2 mg/kg/min in HC and HF, respectively) and the hepatic glucose output rate (HGO) was increased in HF (2.2+/-0.3 vs. 4.5+/-0.2 mg/kg/min in HC and HF, respectively). Rd was significantly correlated with %VF (p<0.01). These results implicate that visceral obesity is associated with insulin resistance induced by HF. In addition, to define whether dietary fat induces insulin resistance regardless of visceral obesity, we compared Rd and HGO between groups 1) after matching %VF in both groups and 2) using an ANCOVA to adjust for %VF. After matching %VF, Rd in HF was significantly decreased by 14% (p<0.001) and HGO was significantly increased by 110% (p<0.001). Furthermore, statistical analyses using an ANCOVA also showed Rd for HF was significantly decreased even after adjusting %VF. In conclusion, we suggest that dietary fat per se could induce insulin resistance in rats fed with chronic HF independently of obesity.

Surgical removal of visceral fat decreases plasma free fatty acid and increases insulin sensitivity on liver and peripheral tissue in monosodium glutamate (MSG)-obese rats

In order to evaluate the role of visceral and subcutaneous fat tissue in insulin sensitivity and lipid metabolism, we measured the fasting levels of plasma free fatty acid (FFA) and insulin, glucose disappearance rate (Rd), and hepatic glucose production rate (HGP) after surgical removal of visceral (VF) or subcutaneous (SF) fat tissue in monosodium glutamate-obese (MSG-Ob) rats. Monosodium glutamate obesity was induced in rats by neonatal injection of MSG. Surgery to remove fat was done at 15 weeks of age. The experiments were done four weeks after the surgery. MSG-Ob rats showed increased levels of FFA, insulin, and HGP and decreased Rd compared to normal rats. In the VF group, the FFA level and HGP were decreased to normal values, Rd was partially normalized, but the level of insulin did not change significantly compared to MSG-Ob. In the SF group, FFA and Rd were partially normalized, but HGP was not suppressed significantly compared to MSG-Ob. These results suggest that visceral fat affects the insulin sensitivity of liver and FFA concentration more than subcutaneous fat; however, no significant difference was shown on whole body insulin sensitivity and fasting insulin concentration.

The effect of short-term intensive insulin therapy on insulin secretion of different phases in newly diagnosed type 2 diabetics / 中国糖尿病杂志

Objective Hyperglycemic clamp technique (HGCT) was performed to evaluate the effect of short-term intensive insulin therapy on the first and second-phase (1PH and 2PH) insulin secretion and maximum insulin secretion (MIS) in newly diagnosed type 2 diabetics. Methods Twelve volunteers with normal glucose tolerance (NC group) and six newly diagnosed type 2 diabetics (DM group) were included and HGCT was performed to assess the function of pancreatic islet beta cell. Then HGCT was repeated in the 6 patients following two week intensive insulin therapy. Results The levels of secreted insulin in 1PH, 2PH and MIS were 257?36 mU/L, 63?5 mU/L and 80?5 mU/L in NC group respectively, and 95?19 mU/L, 34?9 mU/L and 39?12 mU/L in DM group respectively. 1PH insulin secretion was significantly improved in the diabetics following 2 week treatment compared with that before the treatment (135?27 mU/L vs 95?19 mU/L, P=0.01). The insulin secretions in 2PH and MIS were slightly increased (40?9 mU/L vs 34?9 mU/L, P=0.09, 46?11 mU/L vs 39?12 mU/L,P=0.08, respectively). Conclusions Short-term intensive insulin therapy can improve the insulin secretions significantly in 1PH and slightly in 2PH and MIS in newly diagnosed type 2 diabetics.

Application of glucose clamp technique in the study of diabetes mellitus / 中华内分泌代谢杂志

The article introduces the applic at ion of glucose clamp technique in the study of diabetes. The changes in insulin sensitivity, insulin secretion, metabolism of glucose, lipids and protein, etc. in euglycemic or hyperglycemic status in vivo can be investigated by glucose cla mp technique.