Diabetes mellitus is one of the most common chronic diseases in nearly all countries, and continues to increase in numbers and significance. Various environmental and genetic factors interact and increase the risk of T2DM and its complications.G proteins are signal transducers that communicate signals from many hormones, neurotransmitters, chemokines and autocrine and paracrine factors. So it is represent some of the best examples of genetic influences that are involved in the determination T2DM. characters. Methods: The study include 37 T2DM without complication and 68 T2DM with complication patients carried out The Specialized Center For Endocrinology And Diabetes (AL-KindyHospital) in Baghdad-Iraq.For the purpose of comparison , 50 control subjects were matched for age , gender and ethnic background(Iraqi Arab). Results: The result showed all samples (patients and controls) bands when analyzed by the wizard genomic DNA purification Kit (Intron, Korea), also the result revealed that the amplified DNA products band of GNB3 gene at level 268 bp in patients and controls. Conclusion: our study revealed that the GNB3 could have an important role in the development of T2DM.