The greatest effect on gene expression is known for the polymorphisms of the regulatory gene regions, such as A–3826G in the 5′ noncoding region of Ucp1, G–866A in Ucp2, and C–55 T in the promoter of Ucp3. Many studies have associated these polymorphisms with the level of Ucp1–Ucp3 gene expression, increased BMI, susceptibility to T2D, higher blood lipid levels, and elevated blood pressure. This evidence concerns the gene UCP3 and type 2 diabetes mellitus.