Kinship analysis of type 2 diabetes mellitus familial aggregation in Taiwan

Background: Family disease history plays a vital role in type 2 diabetes mellitus (T2DM) risk. However, the familial aggregation of T2DM among different kinship relatives warrants further investigation. Methods: This nationwide kinship relationship study collected 2000–2016 data of two to five generations of the Taiwanese population from the National Health Insurance Research Database. Approximately 4 million family trees were constructed from the records of 20, 890, 264 Taiwanese residents during the study period. T2DM was diagnosed on the basis of ICD-9-CM codes 250.x0 or 250.x2, with three consecutive related prescriptions. The Cox proportional hazard model was used for statistical analysis. Results: Compared with their counterparts, individuals who had first-degree relatives with T2DM were more likely to develop T2DM during the follow-up period (hazard ratio [HR], 2.37–27.75), followed by individuals who had second-degree relatives with T2DM (HR, 1.29–1.88). T2DM relative risk was higher in those with an affected mother than in those with affected father. The HR for T2DM was 20.32 (95%CI = 15.64–26.42) among male individuals with an affected twin brother, whereas among female individuals with an affected twin sister, it was 60.07 (95%CI = 40.83–88.36). The HRs presented a dose–response relationship with the number of affected family members. Conclusion: The study suggests a significant familial aggregation of T2DM occurrence; these findings could aid in identifying the high-risk group for T2DM and designing early intervention strategies and treatment plans.