Both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have a genetic and environmental component. If both parents have T1DM, there is a higher likelihood that their child will develop it than if just one parent has diabetes. (46) Furthermore, if one identical twin has T1DM, the other twin has about 50% chance of developing T1DM. (47) This suggests that there is about 50% contribution from genetics and 50% contribution from the environment for the development of T1DM. What those environmental factors are is still not fully understood. With T2DM, if one identical twin develops T2DM, there is about 70% chance that the other twin will develop it. (48) Thus, the genetic component seems to be stronger in the case of T2DM than T1DM.