Diabetes which has been described as an inflammatory disease has provided avenues for investigations on inflammatory markers that might be associated to its development. C-Reactive Protein and Interleukin-6 polymorphisms are among the objects of current investigations. IL-6 (-174)G>C, one of IL-6 functional polymorphisms in the promoter region, has been reported as influencing IL-6 gene transcription and has been associated with elevated CRP levels. Its relationships to diabetes and several diseases have been studied and the frequencies of its genotypes in different ethnic and population groups have been observed previously to vary from 45 to 100%. This study aimed to explore the frequencies of the IL-6 (-174) genotypes in the Filipino population and to find evidence on the association of IL-6 (174)G>C polymorphism to glycemic status and plasma CRP levels in pre-diabetes and Type 2 diabetes mellitus. Two hundred thirty-three (233) subjects (96 type 2 diabetics,84 pre-diabetics and 53 normoglycemics) were used in the study group. Fasting Blood Glucose Tests and Plasma CRP tests were done using Abbott Hexokinase/G6 PDH reagents and Quantitative Immunoturbidimetric CRP Vario Kit (CRP-16-Ultrasensitive), respectively, in the Abbott Architect ci4100. Genotyping of the IL-6 (-174)G>C polymorphism was carried out using Polymerase Chain Reaction – Restriction Fragment Length Polymorphism (PCR-RFLP). Data of this study showed frequencies of 95%, 5%, 0% for the IL-6 (-174) genotypes GG, GC and CC, respectively. The presence of the GC genotype was detected in the diabetic group and none in the pre-diabetic and normoglycemic groups. No adequate evidence of association was found between IL-6 (-174)G>C and Plasma CRP levels ranging from 0.51 mg/dL to 0.9 mg/dL. Significant association was observed between IL-6 (-174)G>C and Plasma CRP levels of 1.0 mg/dL and above (p-value= 0.006). In this study, significant association was shown between IL-6 (-174)G>C and glycemic status (p-value = 0.005) in type 2 Diabetes Mellitus in a Filipino population.
Key words: IL-6 – Interleukin-6, CRP – C-Reactive Protein, Glycemia – presence and level of blood glucose, SNP – Single Nucleotide Polymorphism