Assessment of insulin resistance using surrogate markers in patients of metabolic syndrome

Abstract

Background: Insulin resistance is defined as situation where there is insufficient biological or metabolic response to normal plasma levels of insulin. For precise quantification of insulin sensitivity, the euglycemic hyperinsulinemic clamp may be used, but it is expensive, invasive and used mainly in research settings. HOMA-IR (Homeostasis Model Assessment-Insulin Resistance) and ISI 0,120 (Insulin Sensitivity Index) are indirect markers of insulin resistance. The present study evaluated the usefulness of the surrogate markers for evaluation of Insulin resistance in clinical settings.

Method: This study was carried out on 120 subjects. Of these, 60 subjects presenting with two or more features of metabolic syndrome (Hypertension, Obesity, Dyslipidemia, altered glucose tolerance) were included in the study group. Sixty age and sex matched healthy controls were selected with normal Body mass index. All the subjects underwent a standard Oral Glucose Tolerance Test. Plasma glucose and serum insulin were estimated using Glucose oxidase and ELISA principle respectively. HOMA-IR and ISI 0,120 were calculated using relevant formulae.

Result: The HOMA-IR values were significantly raised in suspected Insulin resistant subjects (6.74±1.24) as compared to healthy controls (0.82±0.017) (p=0.001). ISI 01,20 was significantly low in insulin resistant subjects (3.13±0.17) as compared to controls (20.60±0.37) (p<0.001). Insulin sensitivity index showed a significant negative correlation with HOMA-IR. A significant negative correlation was observed between serum cholesterol, serum LDL-cholesterol and ISI 0,120 indicating that dyslipidemia in metabolic syndrome may result from a decrease in Insulin sensitivity.

Conclusion: HOMA-IR and ISI 0,120 are simple, convenient and sensitive estimates of insulin resistance adaptable for use in clinical practice as well as large-scale epidemiological studies.