LAUSR

BACKGROUND AND AIM Insulin resistance plays a crucial role in the pathogenesis of type 2 diabetes and cardiovascular diseases. Recently, paraoxonase-1(PON1) is reported to have an ability to reduce insulin resistance by promoting glucose transporter-4 (GLUT-4) expression in vitro. Single nucleotide polymorphism (SNP) in PON1 is associated with variability in enzyme activity and concentration. Based on this we aimed to investigate the association of PON1 (Q192R and L55M) polymorphisms with the risk of developing insulin resistance in adult South Indian population. METHODS Two hundred and eighty seven (287) Type 2 diabetes patients and 293 healthy controls were enrolled in this study. All the study subjects were genotyped for PON1 (Q192R and L55M) missense polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) method. Fasting serum insulin level was measured by ELISA. RESULTS The distribution of QR/RR and LM/MM genotypes were significantly higher in type 2 diabetes patients compared with healthy controls. Moreover, the R and M alleles were significantly associated with type 2 diabetes with an Odds Ratio of 1.68 (P < 0.005) and 2.24 (P < 0.005) respectively. SNP 192 Q > R genotypes were found to be significantly associated with higher BMI, cholesterol, triglycerides, LDL, fasting serum insulin and HOMA-IR. Further, the mutant allele or genotypes of PON1 L55M were associated with higher BMI, triglycerides, VLDL, fasting serum insulin and HOMA-IR among adult type 2 diabetes patients. CONCLUSION PON1 (Q192R and L55M) polymorphisms may play a crucial role in pathogenesis and susceptibility of insulin resistance thus leads to the development of type 2 diabetes in South Indian population.