Study On The Clinical Use Of Glucose Clamp Technique

Objective①To establish a hyperinsulinemic-euglycemic clamp technique,a method for the precise measurement of insulin sensitivity.②To study the pharmacokinetic and pharmacodynamic properties of the subcutaneously injected long-acting insulin analog-recombinant insulin glargine injections in healthy volunteers using an euglycemic glucose clamp technique, and to evaluate the bioequivalence of domestic recombinant insulin glargine injection preparation(Basalin^TM)and imported recombinant insulin glargine injection preparation(Lantus(R)).③To analyze the metabolic disorders,insulin resistance and cardiovascular risk factors in patients with Cushing's syndrome before and after therapy.Methods①A hyperinsulinemic-euglycemic clamp technique was applied to the study of methodology in 10 healthy volunteers with normal body weight and glucose tolerance.②This single-center,randomized,single-blind,three-period,crossover design study was carried out by an euglycemic glucose clamp technique.After a baseline period of 2 hours,volunteers received single subcutaneous injection of 0.4 U/kg body weight of Basalin^TM,Lantus(R),or Novolin(R)N on each study day.Basalin^TM and Lantus(R)were administrated in all 16 healthy male volunteers,and Novolin(R) N was administrated to only 6 of them.The pharmacokinetic and pharmacodynamic parameters were calculated according to GIR,insulin concentrations,C-peptide concentrations and blood glucose concentrations during the euglycemic glucose clamp test.③Totally 173 patients were retrospectively analyzed in this study.Metabolic syndrome and metabolic disorders were diagnosed according to the definition by Chinese Diabetes Society of Chinese Medical Association in 2004.A hyperinsulinemic-euglycemic clamp technique was applied to measure the insulin sensitivity in 11 patients.The correlation study between insulin sensitivity and cardiovascular risk factors were performed using simple linear regression analysis.Results①The serum insulin concentrations were acutely raised and maintained at 91.57±13.86 mU/L.During maintaining fasting euglycemia(4.99±0.15 mmol/L),the secretion of endogenous insulin and hepatic glucose production were completely inhibited.In comparison with basal concentrations,the secretion of counter-regulatory hormones(including cortisol and growth hormone)were not significantly stimulated.Under these steady-state conditions of hyperinsulinemic-euglycemic,the glucose infusion rate was 11.56±1.74 mg/kg/min.There were no statistical difference in glucose infusion rate between male and female subjects(male 10.53±1.57 vs.female 12.25±1.59 mg/kg/min, P＞0.05).②The injections of insulin glargine did not induce the pronounced peak in metabolic activity(P＜0.01)and serum insulin concentrations(P＜0.05) observed with the injection of NPH insulin,after an initial rise of 2～4 hours, metabolic activity was quite constant over the 24-hour study period.The statistic data were calculated by analysis of variance,two one-sided t tests and 90% confidence interval.There were no significant difference in INS-AUC_0-24h, INS-Cmax and INS-Tmax between the two preparations(P＞0.05).The 90% confidence interval of Basalin^TM-Ln(AUC_0-24h)was 82.0%～105.2%which in the range of 80%～125%,the 90%confidence interval of Basalin^TM-Ln(Cmax) was 78.9%～107.7%which in the range of 70%～143%according to those of Lantus(R).The relative bioavailability of the domestic recombinant insulin glargine injection preparation(Basalin^TM)were(99.2±20.7)%.③Of 173 patients with Cushing's syndrome,metabolic disorders were presented in 169 patients(97.7%),metabolic syndrome in 88 patients(50.9%), overweight or obesity in 100 patients(57.8%),arterial hypertension in 143 patients(82.7%),impairment of glucose tolerance in 108 patients(62.4%), and dyslipidemia in 81 patients(46.8%).In 35 patients with clinical data before and after operation,the prevalence of these metabolic disorders and cardiovascular risk factors in the patients with normal circulating cortisol levels were still higher than normal,although these disorders were not as severe as those patients during their active phase of the disease.In 11 patients which accepted hyperinsulinemic-euglycemic clamp test,the M value of patients with Cushing's syndrome were significantly lower than healthy volunteers(4.54±1.77 vs.11.56±1.77 mg/kg/min,P＜0.01).A significant correlation was found between M value and fasting blood glucose(r=0.71,P＜0.05),and fasting serum insulin levels(r=0.71,P＜0.05),and HOMA-IR index(r=0.70,P＜0.05).A significant correlation was not found between M value and serum cortisol levels at 8:00am and 24-hour urinary free cortisol levels(UFC)(P＞0.05).Conclusions①The hyperinsulinemic-euglycemic clamp technique was successfully established.②The results of pharmacokinetic and pharmacodynamic properties demonstrated that the domestic insulin glargine injection preparation(Basalin^TM) and imported insulin glargine injection preparation(Lantus(R))were bioequivalent.The subcutaneously injected long-acting insulin analogrecombinant insulin glargine injections(Basalin^TMor Lantus(R))induced more stable serum insulin concentrations and a smoother metabolic effect than the NPH insulin injection(Novolin(R)N).③Patients with Cushing's syndrome had a high prevalence of metabolic disorders and cardiovascular risk factors.Disease remission or normalization of circulating cortisol levels was not always followed by completely disappearance of metabolic disorders and cardiovascular risk factors which had existed in the active phase of the disease,probably due to a residual abdominal obesity and/or insulin resistance.