Family History of Type 2 Diabetes: Does Having a Diabetic Parent Increase the Risk?

Background: It is well established that there is an important genetic predisposition for type 2 diabetes mellitus (T2DM). Objective: To summarise available epidemiological data regarding T2DM transmission in various populations. Method: Narrative review. Results: The estimated risk for the diagnosis of T2DM increases approximately by 2-4 times, when father, mother or both have this condition. Conversely, many T2DM patients have family members with DM. Studies have suggested that the likelihood of T2DM in the next generation is higher in the event of a diabetic mother than father. Both genetic factors, such as mitochondrial DNA mutations, and environmental components, such as intra-uterine environment, have been implicated in the higher maternal transmission of T2DM. Despite the above findings, some studies in populations with high frequency of T2DM have not corroborated the predominantly maternal transmission. Such works have shown either an excess paternal or an equal transmission of T2DM. Conclusion: It appears that potential biases in reporting family history data, especially between the various racial groups, have contributed to the controversy over the existence of excess maternal transmission of DM.