Diabetes mellitus refers to a group of diseases that affect how the body uses blood sugar (glucose). Glucose is an important source of energy for the cells that make up the muscles and tissues. It's also the brain's main source of fuel. Many genetic polymorphisms are possibly implicated in Diabetes Mellitus. The main polymorphisms are Single-nucleotide polymorphism (-308G>A) in the TNF-α promoter, S477X polymorphism of LPL gene, A6244G polymorphism of IRS-1 gene, Polymorphisms in metallothionein-1and 2 genes, Polymorphisms in genes encoding adiponectin (ADIPOQ) and interleukin-6 (IL6), G Protein β3 Gene Variant, Endothelial Nitric Oxide Synthase Gene Polymorphisms, Estrogen receptor alpha gene and Renin-angiotensin aldosterone system gene polymorphisms.