Contents - Medicinski Fakultet u Sarajevu - University of Sarajevo

Folia Medica 2011; 46 No 1:48-53function, it may lead to suboptimal resultsin some circumstances (6).Several methods are used for evaluationof the function of β-cells and the degree ofinsulin resistance such as clamp technique,frequently sampled intravenous glucosetolerance test (FSIVGTT) and continuousinfusion of glucose with model assessment(CIGMA) (8).Clamp technique is considered as a referencetechnique for the determination ofinsulin sensitivity in humans, because itdirectly measures the metabolic effect ofinsulin in precisely set conditions. It can beimplemented in euglycaemic, isoglycaemicand hyperglycaemic conditions. However,it is also the most complex technique as itrequires the simultaneous administrationof the glucose and insulin, multiple bloodsampling and experienced operator (a physicianor a technician) over a course of 3 and6 hours, respectively (8).In the quest for noninvasive measurementtechnique for insulin sensitivity, severalfasting or “homeostatic” models havebeen proposed such as fasting glucose/insulinratio (FGIR), quantitative insulin sensitivitycheck index (QUICKI) and homeostaticmodel assessment (HOMA). Thesemethods have been the most frequentlyused techniques in clinical investigations.The fact that these tests require only a singlevenipuncture in fasting state and do not callfor concomitant intravenous access makesthem particularly attractive to patients andclinicians alike (9).Types of HOMA modelHOMA 1: The original HOMA modelHomeostatic model assessment was firstdescribed in 1985 (Matthews et al.). It is astructural mathematical model which allowsvalues for insulin sensitivity (which isreciprocal of insulin resistance) and β-cellfunction, expressed as a percentage of normal,to be obtained if simultaneous fastingplasma glucose and fasting plasma insulinor C-peptide concentrations are known (6).These parameters can be used by means ofthe following formulas (10):HOMA-IR= (FPI x FPG)/22.5HOMA-%B= HOMA-IR – (20 x FPI)/(FPG-3.5)(HOMA-%S= 100/HOMA-IR)IR= insulin resistanceFPI= fasting plasma insulin level; FPG=fasting plasma glucose level% B= % of functional β-cells in the pancreas;% S= % of insulin sensitivityThe relationship between glucose and insulinin the basal state reflects the balancebetween hepatic output and insulin secretion,which is maintained by feedback loopbetween the liver and β-cell. The predictionused in the model arises from experimentaldata in humans and animals (11).The approximating equation, in earlymodel, used a fasting plasma sample, andwas derived by use of the insulin-glucoseproduct, divided by a constant (assumingnormal weight, normal subjects